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HARPS-N USER MANUAL - TNG

1. M 14 3 3 6 jab mul EE 14 3 4 Software Ice DP 14 3 5 Data acquisition Softwaf A desa 15 3 5 1 Short Time Scheduler STS about iii 15 3 5 2 euge LEE 16 3 5 3 Front End Unit Autoguider and Calibration Unit control instrument software 16 3 5 4 Telescope Control SysStetm oi ect eee e HERR E e ERE ERE EORR ai 16 3 6 Data WEIOUATIESTOUM CIC 18 3 7 HARPS N performances nee re eheu E d ecu be a a d e a ORE 19 3 7 1 Spectral format and resolution camion 19 3 7 2 Efficiency of the spectrograph smedede ea 21 3 7 3 Instrumental stability and simultaneous reference seen en ennen nen sn enn sn ene 23 3 7 4 Onssky PLEC1S1ON m i 24 Observing MOES serien eiie i a N E opened bunden 25 4 1 Simultaneous Thorium reference method ennen ener eene eene 25 4 1 1 P rforinance nile lilla NE NIIS NR WE Ne RESTI arena 25 4 1 2 Calibrations scettr ERR IP IRA e eR ERO gestu ORARIA 25 4 1 3 Obseryatlonls ni ae 27 4 1 4 Pipeline data r duction sei eta ees oae e Ee dE eeu 27 4 2 Simultaneous Fabry Perot reference method eese 27 4 2 1 Performance TUUM MM 27 TNG MAN HARPN 0002 4 4 2 2 Calibrations suicidati ve a ertet iia 27 4 2 3 NS A alle eee eb alati 28 4 2 4 Pipeline data red ction 2 n nde e eiu n aaa 28 4 3 Classical fibre spectroscopy erni ooi ee e Rp ee S eue to 28 4 3 1 A
2. Image Observ Type Program Object UT Date Coord PA Expo Time Air Mass HARPN 2012 09 10T06 15 20 295 FITS CALIB CALIB 2012 09 10T06 15 20 295 06 15 20 02 10 25 29 48 35 20 0 0 0 0 0 HARPN 2012 09 10T06 03 47 451 FITS SCIENCE GAPS 2012 09 10T06 03 47 451 06 03 47 02 10 26 29 48 31 600 0 0 0 1 13 HARPN 2012 09 10T05 47 45 089 FITS SCIENCE GAPS 2012 09 10T05 47 45 089 05 47 45 01 58 13 37 32 40 800 0 0 0 1 13 HARPN 2012 09 10T05 25 23 462 FITS SCIENCE GAPS 2012 09 10T05 25 23 462 05 25 23 01 57 23 37 36 23 1200 0 0 0 1 11 HARPN 2012 09 10T05 00 00 176 FITS SCIENCE GAPS 2012 09 10T05 00 00 176 05 00 00 01 58 14 37 15 17 1200 0 0 0 1 07 HARPN 2012 09 10T04 40 42 952 FITS SCIENCE GAPS 2012 09 10T04 40 42 952 04 40 42 01 44 31 44 27 33 900 0 0 0 1 08 HARPN 2012 09 10T04 17 56 745 FITS SCIENCE GAPS 2012 09 10T04 17 56 745 04 17 56 01 57 53 37 27 28 1200 0 0 0 1 03 HARPN 2012 09 10T03 53 58 335 FITS SCIENCE GAPS 2012 09 10T03 53 58 335 03 53 58 01 56 23 37 37 37 1200 0 0 0 1 02 HARPN 2012 09 10T03 27 45 982 FITS SCIENCE GAPS 2012 09 10T03 27 45 982 03 27 45 01 55 58 37 40 18 1400 0 0 0 1 01 HARPN 2012 09 10T03 14 47 195 FITS CALIB CALIB 2012 09 10T03 14 47 195 03 14 47 00 16 21 16 39 08 20 0 0 0 1 06 Figure 21 TNG archive loogbook 8 2 3 Use of archived HARPS N data For convenient archiving of raw observation data and pipeline products dedicated Data Archiving softw
3. Un r B estimate accuracy on H 87Lm s E ooo e NONE NA VERVE de p B gt iiri 1 s vifa plotA mo a ae gt 61 ynin 0 25 ynax 1 05 140 43 8 le smegaplotfic tmp plotA xmin 103 xmax 61 ymin 0 25 Umax 1 peo Reece a iene 40 000 COTAS 02 40 43 8 hadgtVISU megaplotf ic tmp plotB 1337913622 xmin 103 xmax 61 ymin 0 25 ymax 1 05 overy _ FA 02 40 43 8 Recipe obj_TWO_harpn is terminated E a E m Scroll Unlock Scroll Lock Figure 13 Screenshot of the data reduction trigger 3 7 HARPS N performances 3 7 1 Spectral format and resolution The recorded spectral format corresponds well to the calculated values Table 6 gives the order number central wavelength and the total spectral range covered by the respective echelle order at the top center and bottom of the CCD All the orders up to 158 could be localized and extracted using a tungsten flat field lamp while the wavelength calibration was done using the ThAr spectral lamp Figure 14 shows a part of the corresponding extracted and wavelength calibrated spectrum Table 6 Central wavelength and spectral range of the echelle orders Order N Central wavelength A Total spectral range AA A TNG MAN HARPN 0002 20 Figure 14 Portion of the extracted ThAr spectrum order The image quality and thus the spectral resolution varies only slightly in the cross dispersion direction seeError Re
4. Telescopio Nazionale Galileo HARPS N USER MANUAL Draft Manual version 1 2 TNG MAN HARPN 0002 Date 24 04 2012 v1 0 Prepared R Cosentino TNG MAN HARPN 0002 Issue Re V Date Change Record Section Page affected Reason Remarks V1 0 24 04 2012 First version V1 1 V1 2 18 01 2013 28 01 2013 First revision changes TNG MAN HARPN 0002 3 1 Contents 2 Introduction cain rai al AI I RANA Ea 6 2 1 Scope ili 6 2 2 Additional information meissos ninen o a ae a a aaia a 6 2 3 Contact information aiar a a 6 2 4 Acknowledesments sine aaa 6 HARPS lt N Characteristics resida a a ia ani cairo 7 3 1 Instrument OVELVIEW nmm 7 3 1 1 Instrument coupling to the telescope renen ennen ennen ennen ennen ennen nen 9 3 2 Operational OVELVICW aa aaa 10 3 2 1 Biber roi qm 10 3 2 2 Calibration unit CU 2 eic eere tis a soci ae esee daba eo RERO Cbr ORE dod ala ER RCM TR RP ENTRE RR dA 10 3 2 3 Front End Unit EFEU 4 icetecett rete aan 11 3 3 Detector and read out electronics enne eene nene ee es es nene rrne ener s sese nen 13 3 3 1 General detector characteristics hehe nennen nennen nnn 13 3 3 2 A otha enol ea E aad uh ae aa eae ena awake dahil 13 3 3 3 Bn M M M H 14 3 3 4 e e bleniicll gd m 14 3 3 5 SHU
5. 3 HARPS N general schematic view 3 2 Operational overview The HARPS N instrument s mounted on the Nasmyth B focus of the TNG telescope in La Palma It shares the focus with other instruments Dolores and SARG The switch between the three instruments requires only the movement of M4 mirror entrance slider 3 2 1 Fiberlink To send the light from the FEU to the spectrograph we use a 26 m octagonal fiber link This new geometry increases the light scrambling effect and guarantees a very high precision in radial velocity measurement since they minimize spectrograph illumination changes due to the positioning error of the star in the fiber entrance These fibers have shown excellent laboratory performances and demonstrated excellent results on sky A second fibre link connects the Fabry Perot reference next to the spectrograph with the HARPS N Calibration Unit CU 3 2 2 Calibration unit CU The calibration unit contains the lamps and the power supply and provides the reference source thorium tungsten for the FEU Two external high precision references are included The first is already available and consists of a Fabry Perot interferometer The second one a stabilized laser frequency comb is currently under development and will become available in 2013 The CU is connected via two optical fibres to the FEU which redirects the light of the calibration sources into the spectrograph fibres as required The two calibration fibres can be fed
6. 41 exposures is of only 1 08 m s most probably this is completely dominated by the stellar p modes The same star was observed although at much lower frequency during all the four half nights of the first GTO run The obtained dispersion is of the order of 1 5 m s We are convinced that this value will be improved further by optimizing the instrument and the data reduction software We expect that a long term instrumental precision of the about 0 5 m s can and will be attained after the first semester of operations TNG MAN HARPN 0002 25 4 Observing modes HARPS N offers the following observing modes e Simultaneous Thorium Reference observation e Simultaneous Fabry Perot Reference observation e Classical fibre spectroscopy with and without sky 4 1 Simultaneous Thorium reference method The Simultaneous Thorium Reference mode is the base line observation mode to get the best short term accuracy in radial velocity determination from the instrument In this mode fibre B is fed by the Thorium lamp while fibre A is on the stellar target A variable neutral density ND filter is used to keep the Thorium spectrum at a flux level equivalent to a 40 seconds exposure with zero density Since the density to which the ND filter is set is computed by the instrument software from the exposure time as defined in the template The Thorium spectrum which is recorded simultaneously with the stellar spectrum is used to compute the instrument drift from th
7. Zenith Y Start Night End Night Moon Position Moon Velocity Airmass Figure 19 Short Term Scheduler Fora description of all HARPS N templates and the parameters selectable with NSTS consult the HARPS N Template Reference Guide In the fibers illumination scheme as a function ofthe template used is shown Table 9 Fiber illumination scheme as a function of the template used HARPN ech acq objA Star Dark HARPN ech acq objAB Star Sky HARPN ech acq thosimulth Star ThAr lamp 2 HARPN ech acq wavesimulth Star FB HARPN ech cal thoAB ThAr lamp 1 ThAr lamp 2 HARPN ech cal thoA ThAr lamp 1 Dark HARPN ech cal thoB Dark ThAr lamp 2 HARPN ech cal tun A Tungsten Dark HARPN ech cal tun B Dark T ngsten HARPN ech cal tunAB Tungsten Tungsten HARPN_ech_cal_ waveA Wave A Dark HARPN_ech_cal_ waveB Dark Wave B HARPN_ech_cal_ waveAB Wave A Wave B 5 3 Overheads The pipeline overheads are for reference only observations can proceed without the need for waiting the pipeline results Thorium lamps pre heating overhead have to be considered before the start of the afternoon calibrations telescope preset included dome rotation 8 min upper limit for large more than 180deg dome rotation TNG MAN HARPN 0002 34 2 min typical for new pointing within a few degrees from the previous position centering of object on the fibre start of guiding 1 2 minutes depends
8. configurations of the acquisition mode The detector is configured without binning and the readout is using two outputs The readout speeds is 500 kHz per channel and the readout noise is lt 5e The electronic conversion factor is about 1 6 e ADU The HARPS N science detector system is summarized in Figure 7 Figure 7 Detector control system scheme 3 3 2 CCD The CCD is a 4Kx4K back illuminated e2v CCD231 with 15um square pixels It is a device processed from standard silicon process and coated with graded AR coating parallel to the readout direction for enhanced response from 385nm to 691nm from left to right as shown in Figure The CCD is read by two different amplifiers and a difference of several 100 ADUs in the bias level of the two CCDs might be expected Following we present the CCD Quantum efficiency curve as provided by the supplier Astro QE 100C 16 um silicon CCD231 models Readout Split 09 pm DOOR mz Amplifier H Amplifier G Lao 4112 rows 04 350 400 450 500 550 600 650 700 Amplifier F Wavelength nm Amplifier E midband Broadband maxge graded 2048 active pixels 50 blank pixels Figure 8 The CCD coating and quantum efficiency TNG MAN HARPN 0002 14 3 3 3 Cryostat An ESO supplied continuous liquid nitrogen flow cryostat houses the CCD and a preamplifier board A dedicated controller regulates the LN flow control to m
9. either by the same or independently by two different calibration sources Of the two Thorium Argon lamps the lamp THARI is the absolute reference and its use should be minimized Typically it is used for 5 minutes per day during the afternoon calibrations shining on fibre A The lamp named THAR2 is used to measure the instrument drift in parallel with the science observations The lamp can be switch on at any moment It is particularly useful when one of the other lamps burns out in the course of the night The HARPS N Calibration Unit has two linear mechanisms to move the reference fibers between 5 positions Three of the positions have lamps two of which are Thorium Argon hollow cathode lamps while the other one is a filament halogen lamp The others two positions are used for ultra stable external references which can be fed through an optical fiber connection At the moment one of these positions hosts the Fabry Perot interferometer located in the HARPS N cabinet close to the spectrograph TNG MAN HARPN 0002 11 Table 4 CU components Movement component Description Thorium lamps 1 and 2 The Thorium Argon lamps are type 4160AHP from S amp J Juniper amp Co Halogen lamp The halogen lamp is a type 6337 TBC Quartz Tungsten Halogen bulb from Newport Fabry Perot The FP interferometer is located close to the spectrograph 3 2 3 Front End Unit FEU The FEU is the first part of the spectrograph where the incoming light
10. elei eil etie HG HET eu etd obi dede PME tee tenete 28 4 3 2 Calibrati ns oou eere xe Re ete pe e e d a ro ven d b vee E Exe ERR na 28 4 3 3 O A od oo eset eth ei ita 28 4 3 4 Pipeline data reduction nee e Ed e tente e n cene ntu 29 4 4 Focusing of the telescopes cic e etii edt A i EE E a ERE deoa aeter eo 29 4 4 1 Performance cione en Eie e Met bebe a e ee e ete ta ach ie c 29 4 4 2 Template ette ge een te o tein es 29 4 5 IRV ACCUIT ACY sic RI 29 4 5 1 PHOTON NOISE ED 29 4 5 2 Sra nionem 29 4 5 3 Centerime errors Suo Ru ar RE T saad ER e te e d P QNI NR 30 4 5 4 Thorium calibration errors hen ehe ee nennen nnne 30 5 Preparing the observations iaia de 30 5 1 Introduction P 30 5 2 Introducing Observing Blocks eeeeeeeeeeeeenenenenenememem em eene eene nitens e tenete 30 S T Observing blocks ine e eee eee dr dep RE Re deir iuge 30 5 2 2 New Short Time Scheduler NST S oceaan laana nne 30 5 2 3 Science templates x e bud den tate ao E m e POE fero Ded 31 5 2 4 Calibration templates manir peranna EE art 31 5 2 5 Technical templates cui A AAA ale 32 5 3 Overleads ceps tinte 33 5 3 1 Fast time series observations asteroseismology renen ener ennen nono nnnnnnnn ns 34 5 4 The HARPS N Exposure Time and Spectral Format Calculator 34 6 Observing With H ARPS sisi tie n Eee eoe PEE Dre Re Ee ERR ae Frane E air 36 6 1 Beftore the night it dee
11. en ee ag a ees 36 6 2 D ring theni ghee ii ih aaa ai 36 6 2 1 Target acquisition guiding focusing ennen ennen renen ennen ennen nen nerne 36 6 2 2 PolntIng TESTEICCION picnic aaa 36 6 2 3 Night calibrations eic dadini eiae 37 6 2 4 Real time display ua a t et ba eed 37 6 3 Observing very faint stars ie 37 6 4 Asteroseistiolog y o e p e ee 37 6 5 End Of the mi he ad A aaa eee RR Tp eere pee o 37 7 Data products and archiving ii 39 7 1 Data products sini A A ilo ELIA lai 39 7 1 1 Raw data dle cios ti A va 39 7 1 2 Red ced daa le A ili aa 39 TNG MAN HARPN 0002 5 7 2 Data Archiving E ET 40 7 2 1 ENG rand Trieste archives ee ie nziriri iaia iii iii 40 42 2 TING data logging code er air ade 40 7 2 3 Use of archived HARPS N data 0 0 41 8 The Reduction of HARPS N Data eene e e e e I e e eren n nn enn 43 The HARPS N data reduction pipeline 43 High accuracy radial velocities i ui 43 A 1 Data namin rules ni p e ED E i B HERE Y 43 TNG MAN HARPN 0002 6 2 Introduction 2 1 Scope This User Manual is intended to give all necessary information to potential users of the HARPS N instrument to help them decide on the opportunity to use the instrument for their scientific applications to be used as a reference when writing observing proposals and when preparing the observations For this purpose we give An overall description of
12. fits NONE WAVE WAVE FP 02 40 35 1 Template used for CCF computation K5 N 2012 05 24T22 28 13 000 fits NONE WAVE WAVE FP 02 40 37 3 Guessed RY is at 12 5 km s N 2012 05 24T22 29 18 000 fits NONE WAVE WAVE FP 02 40 38 8 Correlation fiber A C 36 4 RV 13 01243 km s FWHM 6 2345 km s maxcpp 43 5 N 2012 05 24T22 30 22 000 fits NONE WAVE WAVE FP 02 40 39 1 On fiber A estimated RV accuracy on spectrum 8 31 m s ia DIS come WAYE VE Ze hacia tete by supe SENG i 8 ymin 0 25 1 05 Y 4 340739 2 megaplotfic mp plotA Xmin 33 xmax B uymin 0 25 umax 1 N 2012 05 24T23 54 22 000 fite HD127334 STAR WAVE 02 40139 2 hadgtVISU megaplotfic tmp plotB 1337913622 xmin 33 xmax 8 ymin 0 25 ymax 1 05 overplo N 2012 05 25T00 15 07 000 fits NONE WAVE WAVE FP 02 40 39 3 Number of Cosmic corrected 71 on fiber B N 2012 05 25T00 16 12 000 fits NONE WAVE WAVE FP 02 40 39 3 Barycentric Earth RV correction 11 01835 km s N 2012 05 25T00 24 53 000 fits K00141 STAR SKY 02 40 39 3 Template used for CCF computation KS N 2012 05 25T00 59 14 000 fits K00141 STAR SKY 02 40 41 9 Guessed RY is at 82 5 km s N 2012 05 25T01 31 58 000 fits K00356 STAR SKY 02 40 43 5 Correlation fiber B C 86 8 RV 82 33580 km s FWHM 1 0424 km s maxcpp 2 1 N 2012 05 25T02 04 18 000 fits NONE WAVE WAVE FP 02 40 43 8 On fiber B estimated RV accuracy on spectrum 13 67 m s y A a 140 45 8
13. not perfectly constant Nowhere on the CCD the spectral resolution decreases below R 1007000 however Table 8 Measured spectrograph parameters Wavelength range on the CCD 390 1 691 5 nm Spectral resolution at center 1207000 Order width FWHM at center 3 2 pixels Sampling at CCD center 0 0014 nm pixel Separation of fibers 16 8 pixels TNG MAN HARPN 0002 21 Figure 15 Raw of a spectrum recorded by HARPS in the wave mode Two spectra can be distinguished each one corresponding to one spectrograph fiber illuminated by A the star lower fiber and B the simultaneous FP upper fiber 3 7 2 Efficiency of the spectrograph The total calculated HARPS N efficiency obtained at the center of the echelle order blaze condition is shown in Figure 16 The efficiency of various subsystems is also shown in the figure The instrument efficiency has been computed using the efficiency data for each single optical component measured in the laboratory The shape of the instrument efficiency follows the blaze response of the cross disperser grism the rapid cut off below 380 nm is however accentuated by the band pass filter which has been installed in order to prevent the second grism order below 360 nm to be imaged on the CCD For the CCD we indicate the QE values measured in laboratory by E2V Telescope and atmosphere efficiency have been estimated from experience values The slit efficiency indicates an average value compu
14. ranges from 385nm to 691 nm The resolution of the spectrograph is given by the fiber diameter and reaches an average value of R 115000 At this resolution each spectral element is still sampled by 3 3 CCD pixels The spectrograph is mounted on a nickel plated stainless steel mount and contains no moving parts Furthermore in order to avoid spectral drifts due to temperature and air pressure variations it is accurately controlled in pressure and temperature In Figure 1 the mechanical mount on the left and the installation inside the vacuum vessel on the right are shown A summary of the main HARPS N characteristics is given in Table 1 TNG MAN HARPN 0002 Figure 1 HARPS N mechanical design and vacuum vessel Table 1 Harps Main Characteristics Spectrograph type Fiber fed cross dispersed echelle spectrograph Spectral resolution R 115 000 Fiber field FOV 1 Wavelength range 385 nm 691 nm Total efficiency e 8 550 nm incl telescope and atmosphere 0 8 seeing Sampling s 3 3 px per FWHM Calibration ThAr Simultaneous reference feed by 2 fibers CCD Back illuminated CCD 4k4 E2V chips graded coating Pixel size 15 um Environment Vacuum operation 0 001 K temperature stability Global short term precision 0 3 m s 10E 9 Global long term precision better than 0 6 m s 2x10E 9 Observational efficiency wavelength accuracy SNR 50 per extracted pixel on a Mv 8 TEx
15. stable and strictly controlled instrument and data reduction software designed and optimized for the purpose The pipeline RV determination is optimized for data taken in the simultaneous Thorium reference method The short term RV accuracy of HARPS N with the simultaneous Thorium reference method has been demonstrated during the three commissioning phases to be below 1 m s The RV accuracy can be affected by several factors external to the instrument e Photon noise e Telescope focus e Centering errors e Thorium calibration errors 4 5 1 Photon noise For a G8 star a RV rmsphoton 3 I m s due to photon noise only is reached with a S N ratio of about 67 per pixel at 550nm The photon noise introduced in the RV measurement scales with the SNR in the continuum as long as one stays in the photon limited and not detector limited domain ie at SNR gt 5 4 5 2 Telescope focus Opposite to HARPS ESO a defocus of the telescope does not introduce any RV offset thanks to the use of octagonal fibers TBC Good focus is however extremely important for efficiency reasons TNG MAN HARPN 0002 30 4 5 3 Centering errors Opposite to HARPS G ESO for which a de centering of 0 5 introduces a RV offset of 3 m s no such effect has been observed on HARPS N thanks to the use of octagonal fibers 4 5 4 Thorium calibration errors A total instrumental error of about 0 5 m s must be expected due to the Thorium simultaneous reference and calibrat
16. the furthest stage at which the data products are still sufficiently generic to be used as inputs for all main HARPS N science cases The main steps of the scientific data reduction are e Bias and dark subtraction e Bad pixels correction e Background subtraction e Order extraction with cosmic rejection e Flat fielding e Wavelength calibration e Merging and rebinning of the spectral orders e Sky subtraction if applicable e Instrumental drift correction if applicable e Flux calibration Cross correlation with a numerical template e Radial velocity computation For HARPS N the final products of the DRS process have been found to be the extracted background subtracted cosmic corrected flat fielded and wavelength calibrated spectra with and without merging of the spectral orders The possibility to flux calibrate the spectra is also available These products are provided also for the reference fiber sky or simultaneous wavelength calibration if applicable In addition to these reduction products cross correlation functions of the spectra are also computed to provide high precision radial velocities One important feature of the DRS environment is the calibration database in which all calibration products needed to reduce science data are stored The complete calibration database can be accessed at any time by the DRS recipes which always choose the best available calibration dataset TNG MAN HARPN 0002 19 tkTrig
17. 1 m s the target coordinates must be known to within 6 including proper motion 2 the RV of a star needs to be known to within 1 2 km s to give the pipeline a reasonable starting point for the RV computation TNG MAN HARPN 0002 39 8 Data products and archiving 8 1 Data products HARPS N writes FITS files with extensions containing the data of both CCDs The size of one raw data file is approximately 32Mb Data naming rules are summarized in A 1 Data naming rules pag 43 By default the data products of the online pipeline are archived as well Following is an example of the files that are included in the archiving of one exposure 8 1 1 Raw data file HARPN YY Y Y MM DDTHH MM SS SSS fits raw spectra data Full image with header A HARPN Y YY Y MM DDTHH MM SS SSS fits Autoguide full image E HARPN YYYY MM DDTHH MM SS SSS fits autoguide integrated box image G HARPN YYYY MM DDTHH MM SS SSS tbl exposure meter data ascii file 8 1 2 Reduced data file Cross correlation function summary table with extracted RV for each order for M mask HARPN YY Y Y MM DDTHH MM SS SSS_ccf_M_A tbl Cross correlation function matrix in fits format for mask M HARPN YYYY MM DDTHH MM SS SSS_ccf_M_A fits 2D extracted spectrum one row per order HARPN YY Y Y MM DDTHH MM SS SSS_e2ds_A fits 1D extracted full spectrum wavelength calibrated in the solar system baricentric frame HARPN YY Y Y MM DDTHH MM SS SSS_s1d_A fits B
18. ION NONE 180 0 10 3 HARPN_ech_cal_bias 0 0 1 3 HARPN_ech_cal_tunAB Sra oo 22 2 40 Comment 3 HARPN_ech_cal_thoAB 400 1 3 HARPN ech cal waveAB 400 1 3 HARPN ech cal thoB 400 1 Tait Kenan 3 HARPN_ech_cal_waveB 400 1 id 3 OB SCIENCE 1 4 HARPN_ech_acq_objA 10h3 4310601218 1L54 TEL TARG ALPHA 10h39m36 71 47 HARPN_ech_obs_all 11 56 5 0 107 1 gt S OB TECHNICAL ste AA Sa Se 11 5 0 0 Y TELTARG DELTA 43 06 10 1 ner nrAn MADE CCD Dand Mes 24h 00m a ZUR f I EN 08h00m 10h 00m 12h 00m UT j 1 14 1 6 1 8 Horizon s Pole Y Meridian Zenith Y Start Night End Night Moon Position Moon Velocity Airmass wv Figure 10 Short Time Scheduler screenshot 3 5 2 Sequencer The sequencer is the HARPS N observation control software It gets the observation blocks from the STS and executes them according to several XML template files Sequencer templates files define the commands statements and variables to run an Observing Block Moreover the sequencer is able to emulate HARPS N units and display through a GUI the execution status for each of the commands defined in the command template file Figure 11 3 5 3 Front End Unit Autoguider and Calibration Unit control instrument soft
19. LAMP 1 LAMP 2 4 t 4 4 t 4 t Mue T10 prom 74 GUDE gg a m SOL gt t pet x 4 Figure 4 Calibration and Front End Units TNG MAN HARPN 0002 12 Calibration Fibres Figure 5 FEU optical scheme Figure 6 The Front End Unit All optical fibres are connected to the FEU which forms the interface to the telescope The FEU provides several functions 1 Illumination of the object and the reference fibres each can be separately fed by the object the sky light from a calibration source or it can be dark 2 Correction of atmospheric dispersion by means of an ADC TNG MAN HARPN 0002 13 3 House the technical CCD camera for guiding 4 Guide the star in the fibre thanks to the tip tilt mirror acting together with the autoguider system 6 Attenuating the reference light beam from the ThAr lamp via a neutral density wheel to an equivalent exposure time of 20s at zero density This can be done for exposure times from 20s to 5400s 3 3 Detector and read out electronics 3 3 1 General detector characteristics The HARPS N scientific camera is based on an e2v CCD231 scientific grade CCD detector and an ARC generation III CCD controller The detector has been integrated in a continuous flow cryostat CFC supplied by ESO The CCD controller allows different readout modes 1 2 and 4 output readout and different binnings but to optimize the automatic data reduction pipeline and the operations we chose only two fixed
20. N HARPN 0002 Appendix B List of acronyms ADC Atmospheric Dispersion Compensator AG Auto Guider CCD Charge Coupled Device CCF Cross Correlation Function CFC Continuous Flow Cryostat CU Calibration Unit DFS Data Flow System DRS Data Reduction Software E2DS Extracted 2 Dimensional Spectrum ETC Exposure Time Calculator FEU Front End Unit FITS Flexible Image Transport System FWHM Full Width at Half Maximum HARPS N High Accuracy Radial velocity Planet Searcher in the North hemisphere ND Neutral Density NSTS New Short Time Scheduler OB Observing Block RV Radial Velocity SA Support Astronomer SNR Signal to Noise Ratio TBC To Be Confirmed TBD To Be Defined ThAr Thorium Argon TNG Telescopio Nazionale Galileo TO Telescope Operator VA Visiting Astronomer 45
21. TExp Airmass Nrep Template Observation v 1 OB TECHNICAL 00 0 AAA 1 HARPN_instr_Icu_Init pra fre Get Ges se ii FDR MANS DET DPR INS OCS TPL TEL 1 HARPN instr ag init 2 2 222 2 2 1 HARPN tec set lamp mosey meat au as a Gole SIOE Template parameters v 2 OB_TECHNICAL cer fesa SS cxx AQ 9 2 HARPN tec startnight eem qmm pime come men nese cime S N 550nm v 349 OB_CALIBRATION NONE se emm sce 1800 10 3 HARPN ech cal bias 00 1 3 HARPN_ech_cal_tunAB 40 5 Comment 34 HARPN_ech_cal_thoAB 40 0 1 3 HARPN_ech_cal_waveAB eise insana ame sere 400 easy d 3 HARPN_ech_cal_thoB 40 0 1 Tait Kenan 3 HARPN_ech_cal_waveB 400 1 id 3 OB SCIENCE Feige 34 10h 43 0 11 18 11 5 5 0 1 07 1 4 HARPN_ech_acq_objA 10h3 43 06 11 18 11 54 TEL TARG ALPHA 10h39m36 71 4 HARPN ech obs all T 11 56 5 0 1 07 1 gt S OB TECHNICAL SSS AA Sa See 11 5 0 0 Y TEL TARG DELTA 43 06 10 1 ner eran MODE a CCD Dand Moda TTT TRA 00h 00m o4poom S O8h00m ay 0h00m 12h 00m ai PAN LIU Y L ArFIiAnAaAn E 56070 56071 IU Y IN LET PIN PILA ETA N gt CA4JUD ZUIC 08h 00m 10h 00m _ 00 14h 00 TIN 18h 00m 200 00m 22h00m 00h00m in Horizon Pole Y Meridian
22. TT __ TU MERPC component component EL SEGRE rt OCSLib LE Sequencer ActiveMQ Ca F E SEQ OCS EIS x n XML RPC en SEQ FEU PN N EY cu XML RPC SEQFGUI SEQ CU component El Sequencer GUI Z N Sequencer GUI Figure 9 The HARPS N software architecture 3 5 Data acquisition software The camera control and data acquisition system UCam operates under PC control running RTLinux interfaced to a Generation III ARC Controller The software can be run remotely with a network connection to the host computer The UCam software runs on three HTTP server processes Camera Control File Save and Data De multiplexer servers The Camera Control server initializes configures downloads and executes applications The File Save server handles the image data and writes to disk a meta data file It also contains instructions to sample and de multiplex the raw data image The De multiplexer server processes the saved data and saves it in FITS file format A GUI client application is used for controlling the UCam server application 3 5 1 Short Time Scheduler STS STS is the application which allows the user to prepare the observations It helps the astronomer to choose and schedule the targets for the observing night as well as to calibrate the instrument Within the STS the exposures are organized in blocks called the Observation Blocks of three types science calibra
23. abry Perot spectrum which is recorded simultaneously with the stellar spectrum is used to compute the instrument drift from the last wavelength calibration usually done at the beginning of the night The calibration unit contains two identical Fabry Perot spectra For the simultaneous reference method the Fabry Perot in fiber B is used 4 2 1 Performance For estimates of the SNR with an accuracy of about 10 under given observing conditions the ETC available via the HARPS N web pages http obswww unige ch buchschn can be used see section 5 2 2 4 2 2 Calibrations A calibration sequence similar to the Simultaneous Thorium Reference method is recommended TNG MAN HARPN 0002 28 before the beginning of the night 4 2 3 Observations The necessary acquisition and observing templates are available HARPN_ech_acq_wavesimult for star acquisition and setup of simultaneous fabry perot exposures HARPN ech obs all for taking spectroscopy exposures For a detailed description of the templates see section 5 2 2 and the HARPS N Template Reference Guide 4 2 4 Pipeline data reduction The pipeline performs the same reduction as for the simultaneous Thorium reference method section 4 1 4 but it does not correct for the instrumental drift this one not being traced by the Thorium lamp as in the simultaneous Thorium reference method It does not perform sky subtraction For more details about the pipeline Data Reduction Software DRS pleas
24. aintain the temperature of the base plate inside the cryostat at a suitable temperature The CCD mount stage will have a separate temperature control system using a Lakeshore controller to maintain the CCD temperature at its operating value 3 3 4 CCD controller The HARPS N Camera control and data acquisition system UCam uses the controller hardware from Astronomy Research Cameras Inc USA ARC Controllers The ARC controller provides all the bias voltages and clocks required to operate the detector and process the CCD video signal 3 3 5 Shutter A 45mm clear aperture bi stable Uniblitz shutter is mounted just outside the spectrograph vessel to get the timed science exposures The shutter is controlled by its own controller and is located in the detector electronics rack close to the spectrograph The control input to the shutter controller is derived from the ARC controller 3 3 6 Exposure meter The spectrograph possesses an exposure meter which serves to measure the stellar flux and to accurately measure the mid time of the exposure flux weighted mean of the time This exposure meter consists of two photomultipliers one for each of the two fibres entering the spectrograph from the FEU which use the light picked up at the gap between the two sub gratings of the echelle mosaic no light is lost due to this design The flux in both photomultipliers can be read at the instrument console It is also recorded in the FITS header cumulative ave
25. ambling effect and guarantees a very high precision in radial velocity measurement since they minimize spectrograph illumination changes due to the positioning error of the star in the fiber entrance e Increase the reference precision Two external high precision references are included The first is already available and consists of an ultra stable Fabry Perot interferometer The second one a stabilized laser frequency comb is currently under development and will become available in 2013 e Improvement of the image quality and quantum efficiency The CCD is a 4Kx4K back illuminated e2v CCD231 with 15um square pixels It is a device processed from standard silicon process and coated with graded AR coating parallel to the readout direction for enhanced response from 385nm to 691nm from left to right HARPS N is a fiber fed cross dispersed echelle spectrograph based on the design of its predecessor working at ESO 3 6m This successful spectrograph already has proven its capability to achieve a precision better than 1 meter per second and revealed several super earth planets in the habitable zone Two fibers an object and a reference fiber of 1 arcsec aperture pick up the light at the Nasmyth B focus of the telescope and feed the spectrograph either with calibration or stellar light The fiber entrance is re imaged by the spectrograph optics onto a 4kx4k CCD where echelle spectra of 69 orders are formed for each fiber The covered spectral domain
26. ame A description of the observation template is given in the HARPS N Template Guide 5 2 5 Technical templates HARPN instr lcu init for the initialization of the calibration and Front End units HARPN instr ag init for the initialization of the auto guider HARPN tec set lamp to set the power of the lamps HARPN tec startnight to set the instrument for observation HARPN tec endnight to set the instrument in rest position 5 2 6 New Short Time Scheduler NSTS NSTS is the standard tool for the building of observing blocks from the instrument specific templates A comprehensive description including the user manual is available from the Geneve University web pages at http obswww unige ch buchschn Observers using HARPS N in Visitor Mode should prepare their OBs in advance using the HARPS N Instrument Package which is automatically downloaded once NSTS is started and the Offline Mode is selected from the menu OBs prepared at the observer s home institution can be quickly imported in the NSTS running at telescope console and be ready for execution TNG MAN HARPN 0002 33 D 5008 OC Bi xd SOOO O is Mom Place LaPalma Unix Time Offline UT Offline Night Nautical UT 20 58 09 05 17 56 Moon Alpha 06h29m Zone WET MJD 56070 LT Offline LT 21 58 09 06 17 56 Delta 20d28m Offset 0 Date 23 05 2012 ST Offline ST 11 54 07 20 15 16 Vel 24 71km s ID Name Target Alpha Delta Mv Start
27. are is available at Trieste Science Archive It allows the observers to get the observations data choosing the data product they want raw data reduced data or both log files HARPS N data can be requested from the Trieste Science Archive http ia2 oats inaf it index php tn garchive tn g Data taken by observers in Visitor or Service Mode are subject to the usual proprietary period of 1 year According to the Agreement between GTO consortium and the HARPS N Consortium the data taken by the Consortium during their Guaranteed Time are subject to special protection e Raw data and reduced spectra I f 1 in the Earth reference frame at the time of the observation will be made public one year after observations e All raw data and radial velocity measurements obtained by the Consortium will be made public one year after the end of the 5 year Guaranteed Time period In practice this means that data obtained by the Consortium can be requested from the TNG Science Archive as usual one year after the observations However in order to make recovery of precise radial velocities impossible the keywords containing information about the exact time of the observations will be filtered from all file headers raw and reduced by the Archive during the de archiving process This filtering will be applied until one year after the end of the 5 year Guaranteed Time period TNG MAN HARPN 0002 42 INAF O CENTRO ITALIANO ARCHIVI ASTRONOMICI IA2 TNG a
28. by the user Initialization LCU 3 15 minutes AG 1 minute StartNight EndNi ght 22 seconds instrument configuration 8 seconds lt 12 mites 34 sec telescope focusing at the beginning of the night or 8 10 minutes if the condition are critical DRS pipeline for thosimul without RV computation DRS pipeline for objA without RV computation DRS pipeline for objAB without RV computation DRS pipeline extra time for each RV calculation ThAr lamp pre heating once at the beginning of 5 min minimum 10 min recommended 15 the night min maximum 5 3 1 Fast time series observations asteroseismology The shortest recommended exposure time with the HARPS N shutter is 5 seconds while the shortest recommended exposure in simultaneous thorium exposure mode is 20 seconds minimum exposure time to achieve a 15 cm sec instrument drift tracking For each CCD frame there is an overhead readout attachment of fits header etc of 35 seconds readout mode 500 kpx sec With 20 sec exposure time on sky 55 seconds cycles have been achieved The pipeline presently implemented is able to reduce this flood of data in nearly real time Reduction of one frame lasts about 24 seconds the pipeline no frames will be left behind 5 4 The HARPS N Exposure Time and Spectral Format Calculator The HARPS N Exposure Time Calculator ETC models the instrument and detector in their different configurations It can be used to compute the detailed s
29. d in the afternoon or in the closest succeful HARPS N ech cal thoAB exposures The drift correction is not done At present the drift is measured and inserted in the fits header but is not applied to the RV value The user can do tha if he she wishes by simple subtractionRadial velocity and Julian date correction are calculated in the solar system barycenter reference based on the Bretagnon amp Francou 1988 VSOP87E planetary theory Radial velocity computation is automatically done for all exposure types when a radial velocity value different from 99999 is provided by the TARG RV parameter Conversely RV calculation can be turned off by entering 99999 The RV must be provided with an accuracy better than 1 2 km s For more details about the pipeline Data Reduction Software DRS please refer to the DRS user manual For pipeline execution times see section 5 4 1 4 2 Simultaneous Fabry Perot reference method The Simultaneous Fabry Perot mode is the base line observation mode to get the best short term accuracy in radial velocity determination from the instrument In this mode fibre B is fed by the Fabry Perot while fibre A is on the stellar target A variable neutral density ND filter is used to keep the Fabry Perot spectrum at a flux level equivalent to a 40 seconds exposure with zero density Since the density to which the ND filter is set is computed by the instrument software from the exposure time as defined in the template The F
30. dard simultaneous thorium mode or without simultaneous reference in case of faint objects with m gt 12 Fiber A ThAr measured drift Fiber B FP measured drift Fiber B Fiber A differential drift Drift and differential drift m s a un UJ N e o ha N UJ gt un n N 00 of exposure 1 per minute Figure 18 Short term stability of the spectrograph and quality of the FP and ThAr tracking technique 3 7 4 On sky precision HARPS N makes use of octagonal optical fibers and a double scrambler which when combined are supposed to perfectly scramble the light illuminating the spectrograph and thus remove any potential guiding effect on the measured radial velocity On HARPS N south an effect of the order of 3 to 4 m s was measured when moving the star from the center of the fiber to the edge This effect was observed to be symmetric with respect to the fiber center and fully understood as a consequence of differential pupil illumination of the spectrograph due to non perfect scrambling by circular fibers This experience led us to use octagonal fibers for HARPS N Tests in the laboratory had already shown that we could expect an excellent performance but tests on the sky and using a real star had to be performed Summarizes the results of this test During a night with good atmospheric seeing conditions always below 1 arcsec we have measured the radial velocity of the star HD 89269 During this sequence we have alter
31. dmonmon Sequencer Wed May 23 05 2 XT OO OF OF OV OF On Sequencer Wed May 23 05 20 49 UTC 2012 Status ENDED OBSERVATION gZZZZESESSEREEE UTC 2012 Template HARPN tec set lamp UTC 2012 gt launch CAL setlamp UTC2012 Tem n HAREN tec_endnight UTC 2012 gt la gui E UTC 2012 gt UTC 2012 gt I UTC 2012 gt Reading CCD Not implemented 5 ObsBlockStatus ENDED FE_initicuusb o FE initmon FE move FE readmon FE sendtelem FE setNDTung O FE setfibre FE setndZero etndbyexp artadc IL arenemon O startmonmon FE stopadc FE stopgettele FE Stopmon FE stopsendte VC endmeter C exppower C initexp C recmeter etshutters C setshutters tartexp startmeter VC startmeter topexp useshutter MC Figure 11 Sequencer GUI screenshot Edt Operate Took 20 Window He Ti ER rocas Ft 11668 LUCA i ll File Edit UnZoom 0 AG _DevMon vi Operate Tools Window Help gt pde 2000 Motion Dev DevMon Out Name Info A Telemetry Out SWSIM THRES PARALL ELENC RA DEC Figure 12 FEU screenshot Autoguider and Front End Monitor TNG MAN HARPN 0002 18 3 6 Data Reduction Software An automa
32. e refer to the DRS user manual 4 3 Classical fibre spectroscopy Classical fibre spectroscopy can be done in two different ways depending on the target and the goal of the program 1 fibre A on target and DARK on fibre B objA observation 2 fibre A on target and fibre B on the sky objAB observation objA observation should be preferred for objects much brighter than the sky moon background where a careful CCD background correction may be needed For this type of observation the pipeline provides only the spectrum of the fibre A and uses fibre B order location to compute the CCD background objAB observation should be preferred when a sky background correction may be needed The data reduction pipeline provides an extracted spectrum for each fibre The sky correction is left to the user The high stability of the instrument makes wavelength drifts very small If the same calibration sequence than for the simultaneous Thorium reference method is run before the beginning of the night a RV accuracy generally better than 3 m s along the whole night can be expected 4 3 1 Performance For estimates of the SNR with an accuracy of about 10 under given observing conditions the ETC available via the HARPS N web pages http obswww unige ch buchschn can be used see section 5 2 2 4 3 2 Calibrations A calibration sequence similar to the Simultaneous Thorium Reference method is recommended before the beginning of the night 4 3 3 Obs
33. e FEU The object is centered on the entrance of the science fibre and kept there by an automatic dynamic centering algorithm The guiding accuracy may introduce radial velocity errors but considered the use of octagonal fibers the expected errors are well below the accuracy attainable with HARPS Users with crowded fields close binaries faint objects etc should prepare finding charts The guide camera can guide on stars of magnitude up to 15 5 seeing 1 0 arcsec TBC In the fibre AB spectroscopy mode object sky the observer should verify that the sky fibre is not contaminated by light from other sky objects This should in the first place be done by watching the count rate of the exposure meter photometer B It is important that the telescope is well focused at all times It is recommended to have a through focus sequence performed using the focus template when the image quality observed on the guiding camera deteriorates significantly or whenever there is a significant temperature change few C 6 2 2 Pointing restrictions The telescope dome shall be closed when any of the following weather conditions occur on the TNG Weather Panel webpage http tn gweb tn g 1ac es weather Wind speed gt 15 m sec e Humidity gt 85 e Temperature within 2 of dew point The telescope shall not be pointed into the wind when the wind speed is more than 10 m sec The TO will make the decision to close the dome as necessary VAs
34. e instrument or observing the star the second spectrograph fiber B is always illuminated by a spectral reference source in this case a Fabry P rot FP etalon illuminated in white light The stable FP records potential drifts of the instrument occurred between calibration and observation Once expressed in terms of radial velocity the recorded value can be subtracted from the measured stellar radial velocity to correct for these drifts We have done laboratory tests to measure the performances of the simultaneous reference technique An example is shown in Figure 18 which shows the radial velocity of the ThAr fiber A and FP fiber B spectral sources as a function of exposure number Since one exposure was taken every minute the series represents a time span of about 5 hours During this time we have made a stress test of the instrument by pumping on the vacuum chamber and by changing the temperature of the detector dewar both producing absolute radial velocity changes of several meters per second The obtained results are very satisfactory During the first hour during which the instrument was not touched the radial velocity remains stable well within the 1 m s level It must be noted that this means that the spectrum did not move in absolute terms by more than 0 001 pixels or 15 nm on the scientific CCD This is actually the typical stability obtained with HARPS N during a night despite the fact that the thermal control s
35. e last wavelength calibration usually done at the beginning of the night The calibration unit contains two identical ThAr lamps For the simultaneous reference method only the lamp THAR2 can be used The lamp THAR1 should be used as a reference only for the afternoon calibrations and switch off afterwards Ideally this should prolong the life time of this reference lamp 4 1 1 Performance For estimates of the SNR in the HARPS N mode under given observing conditions the Exposure Time Calculator ETC included in the New Short Term Scheduler NSTS available via the HARPS N web page http obswww unige ch buchschn can be used with an accuracy of about 10 The relationship between photon noise induced radial velocity error and S N is given by the following formula 100 S N 550nm rms m s As a rule of thumb an photon noise error of 1 3 m s or S N 50 can be achieved for a 8th magnitude K0 dwarf in 60 seconds in the HARPS N mode Note that due to the small fiber aperture on the sky 1 the performances assume a seeing better than 1 and critically depend on seeing 4 1 2 Calibrations The Simultaneous Thorium Reference Method needs a sequence of calibration exposures to be taken before the beginning of the night No further calibration exposures are required during the night In order to produce the correct calibration sequence the available observing block RV Standard Calibration should be exec
36. ended not to use the simultaneous Thorium reference method but to rely on the excellent short term stability of HARPS N and take separate wavelength calibration exposures immediately before and after the science exposure to interpolate and remove possible instrumental drift errors The additional time spent on this is negligible given the long science integration 6 4 Asteroseismology Asteroseismology observers need to pay special attention to the guiding behavior continuous control by the observer Also it is recommend to use the NSEQ parameter to produce exposure multiplication instead of duplicating OBs This method will save useless re acquisition of the star and thus produce a considerable gain of time 6 5 End of the night No further calibrations are necessary after the end of the science observations To prolong the life of the calibration lamps HARPS N is switched to the so called Dark mode All lamps still in use at the time are thereby switched off and the dust cover in the fibre adapter is put in place to protect the fibre entrance All electronics are in stand by all internal house keeping functions temperature and pressure control logging continue to operate TNG MAN HARPN 0002 38 7 The Reduction of HARPS N Data The HARPS N data reduction pipeline Every HARPS N frame is processed by the online pipeline Depending on the observation the pipeline uses different reduction recipes Results of the reduction are e E
37. erence along the years Each exposure is used to build a wavelength solution The instrumental drift with respect to the previous calibration frames is measured expressed in m s If accepted by the built in quality control the wavelength solution is stored in the local calibration data base and used for the subsequent reduction of the scientific exposures of the following night Template HARPN ech cal thoAB 2 for reasons of redundancy Fabry Perot exposures in which both fibres are simultaneously fed by light from the Fabry Perot interferometer The Fabry Perot interferometer illuminates fibre Aand fibre B The instrumental drift with respect to the previous calibration frames is measured expressed in m s If accepted by the built in quality control the wavelength solution is stored in the local calibration data base and used for the subsequent reduction of the scientific exposures of the following night Template HARPN ech cal waveAB 1 Thorium exposures in which fibres B is fed by light from the ThAr2 lamp Template HARPN ech cal thob Fabry perot exposures in which fibres B is fed by light from the Fabry Perot reference Template HARPN ech cal waveB The user may then repeat a sequence of flat fields with more than 5 exposures if a SNR higher than 300 is aimed at in later science exposures The RV Standard Calibration acquires 5 flat exposures and reaches a Signal to Noise Ratio SNR of about SNR 400 at 450nm 500 at 550n
38. ervations The necessary acquisition and observing templates are available e HARPN ech acq objA acquisition and setup for fibre spectroscopy with the object in fibre A e HARPN ech_acq__objAB acquisition and setup for fibre spectroscopy with the object in fibre A and sky in fibre B TNG MAN HARPN 0002 29 e HARPN ech obs all for taking spectroscopy exposures 4 3 4 Pipeline data reduction The pipeline performs the same reduction as for the simultaneous Thorium reference method section 4 1 4 but it does not correct for the instrumental drift this one not being traced by the Thorium lamp as in the simultaneous Thorium reference method It does not perform sky subtraction For more details about the pipeline Data Reduction Software DRS please refer to the DRS user manual 4 4 Focusing of the telescope A telescope focusing procedure can be done with the focus template The template points the selected star set the spectrograph executes the focus procedure and move the telescope M2 mirror 4 4 1 Performance The focus template reaches the optimum focuses of the telescope if the seeing conditions are stable The procedure takes 8 minutes to execute For more details about the fofus procedure Please refer to the HARPS N operation guide manual 4 4 2 Template The necessary focusing template is available e HARPN focus focusing of the telescope 4 5 RV accuracy The high RV accuracy obtainable with HARPS N is a result of an extremely
39. ference source not found Table 7 The variation is below 10 across the whole CCD In main dispersion direction we encounter a larger spread in image quality of the order of 20 30 increasing toward the red side of the echelle order due to expected anamorphism This effect is however mostly compensated by the echelle grating dispersion which increases by about the same amount from the blue to the red side of the echelle order Table 7 Image quality of the spectrograph The FWHM of a spectral line expressed in pixels is indicated for different positions on the scientific CCD Y 2000 Y 4000 Dispersion KER Cross dispersion X 2000 Dispersion Cross dispersion X 4000 Dispersion Cross dispersion The measured optical parameters are listed in Table 8 These have been determined by means of ThAr calibration exposures The performances are all compliant with the specifications The image quality could not be measured directly thus we give here only a upper limit estimated from the FWHM values for the spectral lines given in Table 7 In order to compute the spectral resolution one has to multiply these values by the pixel size expressed in wavelength At 530 nm for example in the center of the CCD the scale is 0 001415 nm pixel and the spectral resolution taking into account the measured spotsize is computed to about R 1247000 Because of the changing dispersion and image quality along the orders the spectral resolution is
40. from the telescope and from the calibration unit is conditioned and collimated in the fibers In this stage the incoming beam from the telescope is corrected by the atmosphere dispersion corrector ADC The star is maintained in the fiber thanks to the tip tilt mirror acting together with the autoguider system The folding mirror selects which object reference configuration has to be put into the fibers The optical scheme in Figure 5 shows the optical path inside the FEU and the main components Table 5 FEU components Movement component Description Calibration fold mirror linear mechanism with 4 fixed positions Dust Cover linear mechanism with two positions open close Guide camera FLI PL47 20 TBC Connection to the LCU in the control rackis via USB Guide camera ND filter Two rotating wheels with three filters and a transparent glass each producing attenuation density from 0 to 6 factor 1 to 170007000 Calibration ND filter Two rotating wheels with unconstrained motion can be set to any position in 360 deg Attenuation range of 1 to 300 ADC prism Two atmospheric density compensation prisms with unconstrained motion Tip tilt mirror Precision piezo motor and strain gauge position sensors CU FEU CA THORIUM FOLD _ T8 SELECT 1 LAMP EF MIRROR opal Maske gt f c1 RELAY 1 T 4 AA a T1 GUIDE ci T9 SELECT 2 4 T2 cam m F TER 1 La puts bows m RELAY 2 ar T3 ANER TS MENS SPARE SPARE LTER 2
41. intrinsic noise or jitter Nevertheless even for a quiet star the obtained precision depends on the spectral line width depths and density which all depend partially on the spectral type In order to provide a bench mark for the transformation between SNR and expected radial velocity precision we focus on a quiet non rotating KO dwarf In this case a SNR per extracted pixel of about 50 is obtained on a star with m 8 in 60s At this SNR value a radial velocity photon noise limited precision of the order of 1 3 m s can be expected TNG MAN HARPN 0002 23 250 200 150 SNR computed 100 SNR per extracted pixel SNR measured 50 3800 4300 4800 5300 5800 6300 6800 Wavelength Angstroem Figure 17 Measured signal to noise ratio SNR of HARPS N red curve compared with the values computed by the exposure time calculator of the STS blue dcurve The efficiency tests have be carried out on HD 127334 a mv 6 36 G5 star The exposure time was of 120 seconds 3 7 3 Instrumental stability and simultaneous reference When observing in wave mode it is possible to feed fiber A with a ThAr spectrum and fiber B with the FP spectrum By doing so it is possible to a track possible instrumental drifts and b estimate the power of the simultaneous reference technique This technique is employed in HARPS N to remove possible instrumental drifts from the stellar radial velocity While calibrating th
42. ion drift tracking and zero point The zero point error is by far the dominant source with a contribution of 0 3 to 0 4 m s 5 Preparing the observations 5 1 Introduction HARPS N uses the way of observing based on pre prepared Observing Blocks This chapter describes the philosophy behind this concept the available tools and the HARPS N specific input In order to reach the full performance of HARPS N with respect to the determination of accurate radial velocities the following items should be noted 1 to achieve an accurate solar system barycentric Radial velocity correction of 0 3 m s the target coordinates must be known to within 3 including proper motion 2 The RV of a star needs to be known to within 1 2 km s to give the pipeline a reasonable starting point for the RV computation 5 2 Introducing Observing Blocks An Observing Block OB is a logical unit specifying the telescope instrument and detector parameters and the actions needed to obtain a single observation It is the smallest schedulable entity which means that the execution of an OB is normally not interrupted as soon as the target has been acquired and centered on the fibre An OB is executed only once when identical observation sequences are required e g repeated observations using the same instrument setting but different target a series of OBs must be built Usually one OB consists of two separate entities the acquisition template and the ob
43. isector from the cross correlation computed with a MASK mask HARPN YYY Y MM DDTHH MM SS SSS bis MASK A fits Geometry of the order This fits file contains the FWHM of each order for each row HARPN YYYY MM DDTHH MM SS SSS_fwhm order_A fits Geometry of the order This fits file contains the x position of the center of the order HARPN YYYY MM DDTHH MM SS SSS_loco_A fits Flat Field measurement this fits file contains the blaze for each order HARPN YYYY MM DDTHH MM SS SSS blaze A fits Flat Field measurement this fits file contains the flat for each order HARPN YYYY MM DDTHH MM SS SSS flat A fits Wavelength Calibration fits file with the wavelength solution wavelength of each order for each pixel HARPN YYY Y MM DDTHH MM SS SSS wave A fits TNG MAN HARPN 0002 40 Wavelength Calibration ascii file with a list of all thorium lines detected with information about FWHM sig etc HARPN YY YY MM DDTHH MM SS SSS lines A rdb Wavelength Calibration Ascii file with a sample of Th lines intensities and FWHM only for TH calibration frames HARPN YY YY MM DDTHH MM SS SSS spot thAB tbl Fits file with the Reduced tungsten data file Full image Flat Field HARPN YY Y Y MM DDTHH MM SS SSS order profile fits Fits file with the extracted tungsten data file Flat Field HARPN YY YY MM DDTHH MM SS SSS lamp A fits Other summary tables are produced at the end of each night Calibration Ascii file with Bias table cal BIAS result tbl Bia
44. m and SNR 900 at 650nm In case the RV Standard Calibration is not taken the DRS will use the youngest available calibration data This might introduce offsets and possibly have a negative effect on the achievable precision The pipeline performs quality checks on each frame In case one of the frames does not pass the quality check the youngest available calibration data will be used In this case is however advisable to contact the support astronomer on site in order to make sure the general health of the instrument is not compromised TNG MAN HARPN 0002 27 4 1 3 Observations The necessary acquisition and observing templates are available HARPN_ech_acq_thosimult for star acquisition and setup of simultaneous Th exposures HARPN ech obs all for taking spectroscopy exposures For a detailed description of the templates see section 5 2 2 and the HARPS N Template Reference Guide 4 1 4 Pipeline data reduction The online pipeline does spectrum extraction wavelength calibration RV calculation using a template spectrum of ideally the same spectral type as the target star A comprehensive library of stellar spectral templates s being built up Currently it contains templates of the following spectral type others are in preparation templates G2 K5 M2 The pipeline applies the following corrections detector bias dark flatfield cosmic ray removal and rebins the spectrum according to the wavelength calibration obtaine
45. n 1 The instrument is coupled to the telescope through an adapter the HARPS N Front End Unit FEU Two calibration fibers transmit the light from the calibration unit located in the Nasmyth B Focus and inject it in the two science fibers for calibration Table 2 Halogen lamp 3000k Level of diffuse stray light and ghosts as a percent of the flux in the order Order n Wavelength nm Diffused stray light Ghosts 90 680 0 2 0 05 116 527 0 4 0 5 159 385 1 1 Table 3 G3V star 5700 K Level of diffuse stray light and ghosts as a percent of the flux in the order Order n Wavelength nm Diffused stray light Ghosts 90 680 0 2 lt 0 2 116 527 0 3 0 2 159 385 lt 1 lt 2 In the following is presented a brief description of the HARPS N components the fibre adapter on the telescope the calibration unit and the fibre links connecting these components A sophisticated online data reduction pipeline is also part of the system section 8 3 1 1 Instrument coupling to the telescope The instrument comprises two parts the spectrograph which is located in the ground floor of the telescope and the Front End and Calibration unit which it is mounted on the telescope Nasmyth B fork An optical fiber link sends the light from the Front End Unit to the spectrograph Figure 3 show the schematic view TNG MAN HARPN 0002 10 Nasmyth B derotator Ground floor Figure
46. natively centered and de centered the star at the entrance of the optical fiber The de centering was of 0 5 arcsec which means that the star was placed on the edge of the fiber in the identical way we had done this on HARPS N south in 2003 The first remarkable aspect is that the p modes of the star pulsation of about 2 m s semi amplitude are directly visible in the temporal series The second aspect concerns the excellent scrambling and is represented by the fact that no discontinuity is observed in the radial velocities when switching from centered to de centered observations In order to estimate the off guiding effect on the radial velocity we have averaged all centered exposures and compared them to all de centered exposures The difference in radial velocity is of the order of 0 5 m s which is in turn small compared to results obtained on HARPS N south We consider this value to be actually an upper limit of the effect since the measurement noise is dominated by the stellar pulsation This result is thus fully consistent with the laboratory measurement which had indicated an improvement of about a factor 10 on the scrambling efficiency of octagonal fibers compared to circular fibers At the moment of writing no long term radial velocity performances can be reported given the fact that HARPS N was installed in April 2012 and that the first GTO run took place from May 21 to 25 2012 The radial velocity dispersion over 2 5 hours and
47. p 60 sec 60 m s 2x10E 7 ona single line All necessary moving parts are located in the HARPS N Front End Unit FEU with the exception of the shutter which is located just outside of the vacuum vessel The optical design shown in Figure 2 is similar to HARPS S REM S MW Figure 2 Optical layout of the spectrograph Its echelle grating is operated in quasi Littrow conditions off plane angle 0 721 deg blaze angle TNG MAN HARPN 0002 9 and the collimator in triple pass mode A white pupil configuration has been adopted with the cross disperser placed at the white pupil The dioptric camera images the cross dispersed spectrum on a detector Two fibres A and B feed the spectrograph one object fibre and one reference fibre science fibres The spectra of the light from both fibres are formed by the spectrograph side by side on the detector Although all care has been taken to avoid stray light and ghosts both are present at some level most noticeably in the blue part of the spectrum Ghosts seem to be due to third order reflections in the grism see Table 1 and 2 for some characteristic values However the dominant effect is cross contamination between the two fibers In the worst case at physical echelle order nr 92 the contamination is of the level of 1 5 after extraction In average however the cross contamination between the two fibers is of the order of 0 5 and in 68 of 70 echelles order lower tha
48. pectral format wavelength and order number as function of position on the detector and the expected SNR for the specified target under given atmospheric conditions as a function of exposure time It is available via the the Geneve University web pages at http obswww unige ch buchschn TNG MAN HARPN 0002 Extended Exposure Time Calculator Efficiency W Object counts 8i Object counts saturation 3 750 4 000 4 250 4 500 4 750 5 000 5 250 5 500 5 750 6 000 6 250 6 500 6 750 7 000 Lambda A Figure 20 Exposute Time Calculator ETC CCD Read Mode Exposure Time sec Pa A IO GS o CR OA ve C Spectral Format C Efficiency Objectc SkyC TotalC SNR Stow Tatto Legend 35 TNG MAN HARPN 0002 36 6 Observing with HARPS 6 1 Before the night Depending on the observing method applied simultaneous Thorium reference classical fibre spectroscopy different sets of calibration exposures need to be taken before the start of the science observations For all three methods it is necessary to take a series of calibration exposures Bias Tungsten Thorium because they are needed for the pipeline to produce optimum results A calibration OB OB Standard Calibration is available in the NSTS and ready for execution to take these exposures 6 2 During the night 6 2 1 Target acquisition guiding focusing Target acquisition is done by th
49. rage and center of gravity The expected count rates as a function of stellar magnitude and the estimated errors in RV are given in table Add the table Mv counts error time RV error The number of dark counts per second fluctuates between 10 and 15 However the data reduction pipeline is currently not using this value to correct for possible departures from the nominal 0 5 value centered exposure 3 4 Software architecture HARPS N SW is organized in modules chained together by the Data Flow System First the chosen targets are scheduled for observation with the new short time scheduler N STS where their parameters are organized in Observation Blocks The prepared OBs are sent on request to the Observation Control System the Sequencer When an OB is get into the OCS all the instrument subsystems are set up according to its definition the telescope the spectrograph and the detector Once the observation has been executed the raw image with the FITS keywords gathered from all the subsystems is registered Then the appropriate data reduction recipe is automatically triggered by the Trigger software and the raw data are reduced TNG MAN HARPN 0002 15 package HARPS ICS au Software Architecture y Short Time Scheduler GUI component EI NTCS Command STS ff Broker i AXML RPC SEQ UCAM I Y Y Y ActiveMQ 2 NTCS 4 Broker TEP Pa F AG Server SEQ STS pes gt
50. rchive TNG ARCHIVEQIA2 Image Gallery E LBT Archive EN Proprietaty data retrieval form Public data retrieval form all metadata calibration images images outside Proprietary period Powered by IA2 INAF Trieste Astronomical Observatory For any problem please contact 142 team Figure 22 TNG national Archive TNG MAN HARPN 0002 43 9 Appendix A Description of archived HARPS data A 1 Data naming rules The raw frames are stored in FITS format by the DFS with the ESO VLT standard naming rules HARPN YYY Y MM DDTHH MM SS SSS fits with YYYY MM DD and HH MM SS SSS being respectively the date and time of the start of the observation Raw frames are written in extended fits format each CCD being on a different plane of the frame Pipeline products are stored in FITS format with the same generic names plus an additional suffix describing its format see next section for details and the specific fibre name A or B For example HARPN YYYY MM DDTHH MM SS SSS _E2DS_A fits is an E2DS format image of the fibre A product by the DRS derived from the HARPN Y YY Y MM DDTHH MM SS SSS fits raw frame Tables in ASCII format are also produced by the DRS The raw data are stored in data raw and the reduced are stored in data reduced The relevant log books of the DRS is named DRS drs32 hn tng iac es Y Y Y Y MM DD It is stored with all the other logs in the data msg directory TNG MAN HARPN 0002 44 TNG MA
51. s table Flat Field measurement this ascii file contains parameter of 4 orders cal FF result HARPN tbl Wavelength Calibration ascii file with the parameters of the thorium wavelength calibration cal TH result HARPN tbl Wavelength Calibration ascii file with the parameters of the FP wavelength calibration cal WAVE result HARPN tbl Fabry perot table for wavelength calibrations RV measurement Ascii file with the Th lines drift in m s measured on fiber B filled only in the simultaneous Thorium reference mode drift result tbl RV measurement Ascii file with results of the CCF with measured RV and RV sigma filled only when the RADVEL field in the template is different by 99999 CCF_results tbl 8 2 Data archiving 8 2 1 TNG and Trieste archives HARPS N raw data are stored locally at TNG and in the central Trieste Science Archive 8 2 2 TNG data logging The user can look up locally the logbook of the observation through the TNG archive logbook see Figure 21 http alexandria tn g iac es lo gbook TNG MAN HARPN 0002 41 Archive Logbook LRS i File Sfoglia Upload SARG Browse NICS stent Operation is very simple download the program run it on a directory and it will create ore Datetime Show Today a file which you use to submit on this form and you ll get a HTML output table a la am Logbook Here you can see the manual of genfitinput IARPN 2012 09 09 YYYY MM DD
52. servation template s For normal science observations HARPS N uses four different acquisition templates different for the various observing modes and one common observing template 521 Observing blocks There are three different observing blocks defined OB_SCIENCE OB_CALIBRATION OB_TECHICAL 5 2 2 TNG MAN HARPN 0002 31 5 2 3 Science templates HARPS N uses the science template to preset the telescope and to set up the instrument configuration for the selected observing mode The following acquisition templates are available HARPS N ech acq thosimult for simultaneous Th exposures HARPN ech acq wavesimult for simultaneous Fabry Perot exposures HARPN ech acq objA for fibre spectroscopy no sky HARPN ech acq objAB for fibre spectroscopy with sky HARPN ech acq eff for fibre spectroscopy sky in both fibers All the acquisition templates require an initial guess of the RV For optimum RV determination the expected radial velocity of the source should be entered with an accuracy of 2km s In case the RV value is not known the value 99999 will start an iterative process which will stop once the input and the output RVs differ by less than 1km s If RV computation is not desired the RV initial guess should be set to 99999 The focus template is included in the science OB because the procedure moves the telescope and uses the guiding camera to calculate the optimum focus HARPN focus is
53. should accept the decision since the reason is exclusively the protection of the telescope from damage At any rate in case of a disagreement the dome should first be closed and subsequently the VA may take up the issue with the support astronomer and finally the TNG director though it is highly unlikely that the decision will be altered The dome may be re opened if weather conditions improve and stay below the operating limits for at least 30 minutes This waiting period is particularly important in case of humidity The TO will further confirm that the condensation on the dome has completely evaporated TNG MAN HARPN 0002 37 6 2 3 Night calibrations Night calibrations in addition to the calibration observations taken before the start of the science observations are only necessary when using the template without simultaneous reference 6 2 4 Real time display Raw data coming from the instrument are displayed on a DS9 Display 6 3 Observing very faint stars As explained in section 4 1 a variable neutral density filter is used to balance the intensity of the Thorium Argon calibration spectrum depending on the exposure time This works correctly for exposure times up to 6000 s For very faint stars which require even longer exposures this may lead to an overexposure of the calibration spectrum with contamination of the stellar spectrum As the ultimate accuracy of HARPS N 1 m s will usually not be reached on such faint stars it is recomm
54. signed for the measurement of Radial Velocities RV at highest accuracy The HARPS N Project is collaboration between the Astronomical Observatory of the Geneva University lead the Harvard Smithsonian Center for Astrophysics in Cambridge USA the Universities of St Andrews and Edinburgh the Queens University of Belfast and the TNG INAF Observatory The project started in 2006 but suffered a two year delay due to financial problems After a re organization of the project in 2010 it was successfully completed in less than two years In March and April 2012 HARPS N was installed at the Nasmyth B Focus of the 3 6m TNG at the Observatory of the Roque de los Muchachos La Palma Island The first commissioning took place in April and the first scientific observation started on May 21 Its purpose is to reach a long term radial velocity accuracy of 1 m s for slowly rotating G dwarfs Such precision enables the detection of low mass Saturn like extra solar planets and low amplitude stellar oscillations The design of HARPS N is based on the experience acquired with HARPS installed at 3 6m telescope in La Silla The basic design of HARPS N is therefore very similar to this instrument The efforts to increase the HARPS N performance compared to HARPS address mainly three issues e Increase of the input beam stability To send the light from the FEU to the spectrograph we use a 26 m octagonal fiber link This new geometry increases the light scr
55. ted at an airmass Z 1 03 and for an effective seeing of 0 9 arcsec In practice we estimate that 0 4 arcsec must be added quadratically to the seeing value to account for additional telescope effects due to image quality and possible defocus TNG MAN HARPN 0002 22 100 8 o 9096 Cp CRE 7 m 80 6 70 60 50 Efficiency 40 Y w gt x x Total efficiency Atmosphere Telescope Front End Slit efficiency 0 9 arcsec seeing 2 Fiber link Spectrograph CGD Atmosphere 30 20 10 ae 0 350 400 450 500 550 600 650 700 Wavelength um Figure 16 Total efficiency of HARPS N black plain curve right hand scale and efficiency of subsystems left hand scale The values have been calculated for each echelle order at its blaze wavelength The fast drop below 380 nm is produced by a band pass filter installed in the fiber link to remove 2 order of the grism The grey area shows HARPS N spectral range An interesting aspect is to measure the on sky performances and derive the instrument efficiency It is however almost impossible to calculate precisely the effective efficiency of the instrument by observing standard stars since the sky conditions telescope focus etc are not known with sufficient accuracy Therefore we prefer just to compare real measurements with calculated count rates This procedure allows us to identify possible discrepanc
56. the HARPS N instrument its performance and its observing modes Information on the preparation of the observations Information on the observing process A description of the HARPS N data and near real time pipeline data reduction The following documents are closely related to this manual and should be consulted as well The HARPS N Startup Manual TNG MAN HARPN 0001 The New Short Term Scheduler User Manual NSTS The DRS User Manual OG MAN HAN 13 0004 Both are available through the TNG web page http www tng iac es instruments harps 2 2 Additional information The latest information updates about the HARPS N instrument can be found on the HARPS N web pages https plone2 unige ch HARPS N harps n operations and observations 2 3 Contact information 2 4 Acknowledgments Most of the contents of this manual is based on information from the HARPS N Consortium Astronomical Observatory of the Geneva University lead the Harvard Smithsonian Center for Astrophysics in Cambridge USA the Universities of St Andrews and Edinburgh the Queens University of Belfast and the TNG INAF Observatory Releases of this document are based on the ESO HARPS User Manual edited by G Lo Curto Feedback on this User Manual from users is encouraged Please email to cosentino tng iac es TNG MAN HARPN 0002 7 3 HARPS N Characteristics 3 1 Instrument Overview HARPS N High Accuracy Radial velocity Planetary Searcher is an instrument de
57. the HARPS N trigger GUI online mode version 5 11 Partial logging mode Trigger controlled plots File Configure Help Reduction Information Window Information returned by Reduction Recipes On fiber A estimated RV accuracy on spectrum 8 31 m s On fiber A estimated RV accuracy on CCF 19 00 m s Number of Cosmic corrected 71 on fiber B Barycentric Earth RY correction 11 01835 km s Template used for CCF computation K5 Guessed RV is at 82 5 km s Correlation fiber B C 86 8 RV 82 33580 km s FWHM 1 0424 km s maxcpp 2 1 On fiber B estimated RV accuracy on spectrum 13 67 m s On fiber B estimated RV accuracy on CCF 139 87 m s Recipe obj TWO harpn is terminated VI Raw Frames Reduction Log Window idata raw 2012 05 24 Messages returned by Reduction Recipes N 2012 05 24T22 21 46 000 fits NONE WAVE WAVE FP IAN 02 40 33 0 On Fiber Bz S N 450nm 0 4 S N 550nm 0 0 S NL650nn 0 0 t 1727 cosmic removed N 2012 05 24T22 22 51 000 fits NONE WAVE WAVE FP pea ut cinto ea ge 140 55 0 lg negaplotfic mp plotA PE AO E AVE WAVE EE 02 40 35 0 hadetVISU megaplotfic tmp plotB 1337913622 overplot 1 xtitl N 2012 05 24T22 25 00 000 fits NONE WAVE WAVE FP 02 40 35 1 Number of Cosmic corrected 42 on fiber A N 2012 05 24T 22 26 04 000 fits NONE WAVE WAVE FP 02 40 35 1 Barycentric Earth RV correction 11 01835 km s N 2012 05 24T22 27 09 000
58. tic data reduction system DRS is included with HARPS N to reduce shortly after the exposure observations for classical spectroscopy and high precision Doppler measurements with simultaneous wavelength reference For science exposures the DRS outcomes are flat fielded wavelength calibrated spectra and when possible and requested barycentric radial velocity of the target Calibration exposures are used by the DRS to calibrate the instrument for best quality scientific reduction The DRS is designed to run automatically like a batch process on the archived frames All relevant parameters required by the DRS are passed to the DRS through the FITS headers of the archived frames Results of the DRS are stored in the FITS keywords of reduced frames The top level of the DRS is represented by a set of programs recipes performing the various calibration and science tasks They take as inputs the raw data produced by the instrument and are executed online Each raw product has its associated DRS recipe which performs the required reduction tasks An additional top layer application Trigger acts as an automatic on line recipe launcher The role of the Data Reduction Software DRS is to transform the raw data produced by the instrument into reduced data of scientific quality These represent the basic products from which the user will start in order to perform the desired specific analysis Therefore the endpoint of the DRS processing is defined as
59. tion and technical Science OBs contain the parameters for the target acquisition the instrument and the detector set up Calibration OBs describe the calibration exposures Technical OBs define the instrument initialization and the start and end procedures of the observing night STS controls the feasibility of the scheduled exposures with respect to the observational conditions and constraints like the limit airmass out of the night placement etc The Exposure Time Calculator which is part of the STS helps the user to optimize the exposure time depending on the SNR and vice versa The STS GUI is shown on Figure 10 TNG MAN HARPN 0002 16 D a A E gt EJ VE 4 te VE OOO O kt Sorin Place LaPalma Unix Time Offline UT Offline Night Nautical UT 20 58 09 05 17 56 Moon Alpha 06h29m Zone WET MJD 56070 LT Offline LT 21 58 09 06 17 56 Delta 20d28m Offset 0 Date 23 05 2012 ST Offline ST 11 54 07 20 15 16 Vel 24 71km s ID Name Target Alpha Delta Mv Start TExp Airmass Nrep S v 1v OB TECHNICAL 00 0 a 1 HARPN instr lcu init 002 222 c2 022 0 DET DPR INS OCS TPL TEL 1 HARPN instr ag init 2 2 222 2 2 1 HARPN tec set lamp mosey meat au as a Gole SIOE Template parameters v 2 OB TECHNICAL 00 0 2 HARPN_tec_startnight 777 2 2 o 2 2 c S N 550nm v 34 OB CALIBRAT
60. used to focusing the telescope Note In the focus OB the HARPN ech obs all must be removed A description of the fofus procedure is given in the HARPS N Operation Guide A description of the acquisition templates is given in the HARPS N Template Reference Guide 5 2 4 Calibration templates Several calibration templates are available However all calibrations necessary for a proper data reduction with the online pipeline are performed by the ready to run calibration OB named OB Standard Calibration The details of this OB are described in section 4 1 2 TNG MAN HARPN 0002 32 Only if additional calibrations are deemed necessary one needs to use one or more of the following templates HARPN ech cal bias for taking bias frames HARPN ech cal dark for taking dark frames HARPN ech cal tunA B for taking order location frames through fibres A or B HARPN ech cal tunAB for taking spectral flat field frames through fibres A and B HARPN ech cal thoA B for taking a wavelength calibration through fibres A or B HARPN ech cal tho AB for taking a wavelength calibration through both fibres HARPN ech cal waveA B for taking a wavelength calibration through fibres A or B HARPN ech cal waveAB for taking a wavelength calibration through fibres A and B If the number of exposures is set different from one in the ech cal tunAB or ech cal thoAB templates the pipeline will wait for the last exposure sum all the exposures and then process the resulting fr
61. uted without changes before the beginning of the night It includes 2 bias exposure The CCD bias is very stable only one bias is therefore needed by the pipeline Template HARPN ech cal bias 2 Tungsten lamp exposures where respectively fibre A and fibre B are successively fed by the Tungsten lamp These exposures are used for order location which is done automatically by the TNG MAN HARPN 0002 26 pipeline The processed products are stored in the calibration database if they pass the quality control of the pipeline and used for the subsequent reduction of the scientific exposures of the following night Template HARPN ech cal tun A sequence of 5 Tungsten lamp exposures defined by NREP 5 where both fibres are simultaneously illuminated This sequence is used by the data reduction pipeline for producing a spectral master flat field which will be stored in the local calibration data base if it passes the quality control by the pipeline and used for the subsequent reduction of the scientific exposures ofthe following night Template HARPN ech cal tunAB 2 for reasons of redundancy Thorium exposures in which both fibres are simultaneously fed by light from the Thorium Argon lamps The THARI long term reference lamp illuminates fibre A the THAR2 lamp inlluminates fibre B During the night only the THAR2 lamp will be used as the reference The ON time of the THARI lamp is minimized in order to keep it as an absolute ref
62. ware The FEU and CU software are LabView modules which controls the movements and settings of the instrument and the autoguider This software can also control the units in stand alone mode as an engineering interface or by the HARPS N sequencer using an XML RPC interface 3 5 4 Telescope Control System HARPS N has an interface to the TCS This interface enables the instrument to send commands to the telescope via the TNG library Currently HARPS N is able to send three commands Pointing AG offsets and M2 offsets to calculate and correct the focus via an automatic procedure The connections between both systems are completely asynchronous but when the command finishes successfully the TCS returns an Ok status When an error condition has arisen the TCS also returns a message back to the sequencer flagging that condition TNG MAN HARPN 0002 000 Observation Control System Command Wait Time msec Simulate o Next Observation 17 Run Queue Exposure seconds Observing Status AG_saveguide AG_setposition AG_stanguide tarttepmon AG stopguide AG_stoptepmon CAL_checklamp l ObsBloc VG RE RE EE NE Sequencer Wed May 23 05 2 Sequencer Wed May 23 05 2 FE adczero Sequencer Wed May y 23 05 2 FE dustcovertl Sequencer Wed May 23 05 2 FE_dustcovero Sequencer Wed May 23 05 2 FE endadcmon Sequencer Wed May 23 05 25 Fe sen
63. xtracted spectrum all modes Precise radial velocity only if parameter TARG RV is defined and different from 99999 e Cross correlation function CCF only if parameter TARG RV is defined and different from 99999 If the parameter TARG RV is defined equal to 99999 the software will compute the radial velocity in an iterative manner This is useful when the RV of the object is not known a priori with an Accuracy of 2km s The pipeline output is available immediately after the processing is finished see section 5 3 It can then be transferred to the offline workstation for further analysis It can also be saved to disk and CD DVD using the Data Archiving Unit see chapter 8 available with HARPS This is typically done next morning by the telescope operator or the Data Handler Administrator The visitor is not requested to produce a backup of the raw data and of the pipeline products High accuracy radial velocities The reduction concept applied by the pipeline for the calculation of high accuracy radial velocities using the Thorium reference method is described in the paper ELODIE A spectrograph for accurate radial velocity measurements by Baranne Queloz Mayor et al A amp AS 119 373 1996 In order to get the full performance of the pipeline with respect to the determination of accurate radial velocities the following items should be noted l to achieve an accurate solar system barycentric Radial velocity correction of
64. y without focusing on the detailed efficiency curve which depends on too many observational parameters Figure 17 shows the measured SNR as a function of wavelength obtained during one of the first GTO nights on May 24 2012 The used star was HD 127334 a G5V star with m 6 36 The exposure time was of T 120 sec and the observation were taken at an airmass of 1 03 and with a seeing of about 0 9 arcsec The best measurement of this night is shown since one has to be sure that efficiency losses due to effects not considered in the exposure time calculator ETC e g varying atmospheric extinction or telescope defocus are minimized The calculated curve was derived for a seeing of 1 arcsec which actually has been chosen to take into account for the 0 4 arcsec image quality losses discussed above The measured signal to noise ratio SNR is in excellent agreement with the calculated curve The curve may slightly differ mainly because a a KO spectrum was used for the computation and b the theoretical values of some sub components may be affected by small errors On the other hand and as mentioned above other aspects such as seeing variations extinction image quality etc cannot be controlled in detail We conclude therefore that at a level of about 20 precision the expected efficiency matches the actual efficiency of the instrument The radial velocity precision obtained on a given star depends on many factors not the least being the stellar
65. ystem of HARPS N has not yet been fully implemented The dispersion on the drift measurements over this same 1 hour period is of the order of 30 cm s This noise has a typical period of 10 minutes It is observed also on HARPS N south and it is possibly due to tiny but periodic temperature variations of the CCD or its dewar It is important to note however that on the differential value one obtains a dispersion of 8 cm s which is almost identical with the combined photon noise precision of the ThAr and FP spectral sources This demonstrates without any doubt that the simultaneous reference technique is able to correct for drifts at the level of 10 cm s and below This statement is strengthened by the fact that over the whole test duration the differential drift never exceeded the 40 cm s level despite the fact that the instrument had been exposed to extreme stress conditions never occurring during standard operations Furthermore the differential drift appears to be compatible with zero after 5 hours which not only confirms the power of the used technique but also demonstrates that our FP based reference source is stable within 10 cm s during an observation night However the FP does not yet provide the full stability on longer time scales e g from day to day probably because of a thermal instability of the temperature regulation As long as this problem has not TNG MAN HARPN 0002 24 been solved we recommend to observe in the stan

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