Cassegrain Instrument Adaptor System (CassIAS) User`s Manual
Contents
1. window that appears when the step size button is selected on the CassIAS GUI One can select the step size for the focus in microns as well as the x and y movement of the guider camera in arcseconds CassIAS Guider Camera The CassIAS uses a Stanford ICCD camera and uses an ICCD controller modified for it The pixel scale is 0 09 pixel and the field of view FOV accessible to the guide camera is 148 to 1 14 East to West and 272 to 252 North to South Figure 1 indicates the size and orientation of the guider camera field of view North down East to the left as well as the size Thus if the telescope is offset to the East then the CassIAS camera stage must be moved West to reacquire the target Remember that the useable FOV is this region with a hole in two of the three mirrors subtracted out to allow light to pass directly to the detector There are two hole sizes which are described below and are indicated on the CassIAS GUI when the appropriate mirror s are selected The FOV of the guider TV is 36 in x and 50 in y and is indicated by the small white rectangle with a white crosshair in the center on the GUI This symbol moves instantly as you move the slider bars and it can also be dragged around using the mouse pointer When you release the mouse button whether you are using the slider bars or dragging the rectangle a move command is then sent to the motor control program The target2. Cassegrain Instrument Adaptor System CassIAS User s Manual Version May 16 2005 Patricia M Knezek Please send comments or suggestions about the manual to knezek noao edu Observing With Cass Focus Instruments The Cass Instrument Adaptor System CassIAS was built by Chris Anderson at the University of Wisconsin to facilitate observing with instruments mounted at the Cassegrain port It is currently used with DensePak In the future the high throughput slit spectrograph from Yale WHTSS may make use of the CassIAS The CassIAS is fed by the WIYN Universal Fiber Feed WUFF which was constructed by Kent Honeycutt of Indiana University The WUFF provides a mount for the instruments as well as a pellicle SAFETY Daily inspections must be made by the OA of the CASSIAS cable wrap In particular the wrap up must not interfere with the instrument or IFU bundle when the CassIAS is rotated to its extreme limits Furthermore tie offs and routing of the cable wrap and IFU bundle must be inspected for breakage and or possible catch points when the elevation is moved 90 or at 5 An instrument can be destroyed if a bundle or cable wrap is caught when slewing the elevation So please be patient while the OA does his her job Finally with the tertiary mirror fold removed the elevation axis is unstable The telescope must be moved slowly with elevation speed set to 0 5 degree per second Starting Up The CassIAS pro
3. G420 filter and the 600 I mm grating 13 9 focus of 9 and a central wavelength of 6700A the exposure times were 10 seconds for bright lines and 120 seconds for faint lines Dome Flats Select the mirror position you intend to observe with using the CassIAS GUI As with the information on the calibration lamps we will add to this as information becomes available With DensePak the 600 I mm grating 13 9 a collimator angle of 30 a collimator focus of 5 and a central wavelength of 6600A Di was able to achieve a peak of gt 30 000 counts in a 12 second exposure The flat lamps were at 3200 A similar result was achieved for the GG420 filter and the 600 I mm grating 13 9 focus of 9 and a central wavelength of 6700A
4. ast The central black hole correctly indicates the size and location of the mirror hole Acquisition Mirror This mirror is selected by clicking on the acq button on the upper left corner of the GUI The acquisition mirror has no hole light from entire field goes directly to the acquisition TV The backside of this mirror sends calibration light to the instrument Calibrations can be in progress while acquiring the target field using WUFF Large Center Hole This mirror is selected by clicking on the large button on the upper left corner of the GUI It has a large hole in center directs light to detector and a correspondingly smaller guide field The hole has not been precisely measured but does appear to be centered on x y 0 and is approximately 100 N S and 120 E W diameter of 200 x240 It is represented on the GUI by a round hole with a radius of 120 Until the hole can be carefully measured we recommend assuming an unvignetted field size for guiding that is 120 lt x lt 252 S 120 lt x lt 272 N no guide field W and 120 lt y lt 148 E Aquiring a Target Move mirror to acq on the CassIAS GUI Move the guider probe to 0 0 by clicking on the zero x amp y button on the GUI Once you have located your target choose either the large or small mirror hole and insert the pellicle by clicking on the in button under the WUFF pellicle slide area of the GUI in the upper left
5. corner Please note that on the WUFF Pellicle TV the orientation is approximately East down and North to the left There is likely to be some small rotation from true East down North to the left as there are no fiducial marks for placing detectors in the WUFF mount The center of rotation with DensePak on the CassIAS port is fiber 48 Using a bright star you can 1 check the center of rotation 2 mark where a star falls on the acquisition TV if placed on fiber 48 or whatever fiber you select and 3 determine the amount of rotation of the WUFF Pellicle TV from East down North to the left You can then have the OA input a rotator offset angle just as is done at the WIYN port for DensePak and SparsePak That rotator offset angle will then remain the same unless changed manually by the OA so the orientation will be fixed Place your target on the desired fiducial with DensePak this is often fiber 42 the center fiber Remove the pellicle from the field of view by clicking on the out button under the WUFF pellicle slide area of the GUI in the upper left corner Move the mirror to small or large whichever you choose Note This must be done before you can see the target with either the WUFF TV or the acquisition TV Guiding at Cass Currently to locate a guide star within the available FOV the OA does a manual search as this isn t correctly integrated into the guide star software yet Note The OA must have
6. is normally run on the OA s computer but can be called up as a window on other computers via ssh It is a fairly simple interface that allows either the OA or the observer to control the various functions of the CassIAS To initialize the CassIAS click on the init all button on the GUI or send a command to move any of the axes this automatically initializes the CassIAS Figure 1 shows the setup of the CassIAS prior to initialization Clicking on the stop all button on the GUI will literally stop all whether it is the guider camera moving in x and y changing focus changing mirror position or sliding the pellicle in or out So make sure you want to stop all movement before hitting that button y CasslAS mirror 0 small acq wrge r WUFF pellicle slide 160 0 160 5 260 230 focus 115 0 115 230 N 260 130 stop all init all zero x amp y step size axis target position message x 0 0 a 0 0 focus 0 0 mirror between acq slide out out Figure 1 The CassIAS Control GUI This image indicates the appearance of the GUI when the CassIAS before it is first initialized The slider bars appear yellow 10 10 Set the step size here then move the mouse pointer over the x y or focus slider trough in the CassIAS window Click the right mouse button to move by the selected step size Click the left mouse button to move by one unit Figure 2 The pop up
7. ocus is either controlled by the slide bar on the left of the GUI or by typing in a specific focus in um in the focus box on the lower left Mirror Positions There are three mirror positions Moving the guider camera to the different mirror positions is done with the CassIAS GUI using the buttons in the upper left corner of the GUI Small Center Hole This mirror is selected by clicking on the small button on the upper left corner of the GUI This position has a small center hole to direct light to the detector and a correspondingly larger guider field It is ideal for DensePak as the hole has a diameter of 86 Note that the hole in this mirror is not centered on the optical axis It is centered at 17 N and 8 W of field center as can be seen in Figure 4 Thus the unvignetted field for guiding is 26 lt x lt 252 S 60 lt x lt 272 N 51 lt y lt 114 W and 35 lt y lt 148 E CasslAS mirror y E aca ia WUFF pellicle slide 160 5 260 230 130 115 60 0 0 115 130 230 260 N stop all init all zero x amp y step size axis target position message x 60 DONE motor off y 58 58 DONE motor off focus 27 27 DONE motor off mirror small small DONE motor off slide out out DONE motor off Figure 4 The CassIAS GUI after selecting small CassIAS mirror with a small hole and offsetting the guider probe to 60 in x south and 58 in y e
8. position of the guide camera that has been accepted by the motor control program is shown as ared circle When a new target position has been accepted by the program the red circle will immediately indicate the new position and the rectangletcross hair will follow the movement of the x and y axes to the new position Finally there is a yellow x which marks the actual position of the camera as reported by the encoders Figure 3 below shows the three different symbols separated out CasslAS mirror small SRR tary WUFF pellicle slide 160 160 in out j 260 230 focus 130 115 0 0 72 115 130 230 260 init all zero x amp y step size axis position message x 0 ERROR comm link is down y 84 0 ERROR comm link is down focus 93 0 ERROR comm link is down mirror acq between ERROR comm link is down slide no response from wuff Figure 3 The CassIAS Control GUI with the three target symbols separated out The white rectangle and crosshair indicate the guider camera FOV and are used to position the guider The red circle indicates the guider camera target position The yellow x indicates the guider camera position according to the encoders and moves with the guider The slider bars appear red because the CassIAS hardware was not connected when this image was taken The guider camera can also be focused using the GUI Note that the focus stage Z stage has a range of 210 to 213 um of secondary motion The f
9. the CIAS camera input to channel 0 on the B level of the dome The OA can bring up the guide stars that are available using the guide star software but the offsets must be input manually in the x amp y boxes on the CassIAS GUI in the lower left As a rough guideline the limiting magnitude in 0 8 seeing with dark clear sky should be 16th mag Once a guide star has been located in the available FOV adjust Cass IAS probe focus using either the focus bar or the focus box on the CassIAS GUI The OA can start guiding and you should be good to observe If you have good astrometry for stars within 200 of your field then calculating the offsets from your target and providing them to the OA may speed up this process Calibration Lamps There are CuAr and ThAr calibration lamps mounted inside the CassIAS To access the lamps they must be connected into the system by Instrument Support or an OA This should be done at the start of your observing run The lamps are controlled by a calibration GUI on ivory s desktop This is the same GUI as is used with the imager on the WIYN port for doing dome flats We will add additional information on exposure times with the different gratings as they are used With DensePak the 600 I mm grating a collimator angle of 30 a collimator focus of 5 and a central wavelength of 6600A Di was able to identify bright lines in a 10 second exposure and faint lines in a 180 second exposure With the G
10. vides not only the optics to feed to the WUFF instrument but also the comparison lamps for calibrations a guider camera and an interface to the rotator In order to use the CassIAS for on sky observing an OA or WIYN support staff must initialize the CassIAS ROTATOR This can take up to 5 minutes so be prepared It is not necessary to initialize the rotator to obtain comparison lamp calibrations and zeros Nominal telescope focus The nominal telescope focus change from MiniMo to the CassIAS with DensePak is around 1000 units Rotator Limits The rotator can move from 90 to 90 Observations of a target should be planned so that the rotator will not hit a limit as the rotator unwrap will take several minutes The CassIAS GUI The CassIAS contains three mirrors that can be inserted into the light path Two of the mirrors contain holes allowing light to pass through to the detector The third is a solid mirror used for target acquisition On the backside of the acquisition mirror is another mirror that directs light from the CuAr and ThAr comparison lamps onto the detector The CassIAS also contains a guider camera that can be positioned The CassIAS GUI controls all these functions This GUI also allows the pellicle in the WUFF to be inserted for target positioning on the detector and removed for observations All of these are described in more detail below Figure 1 shows a snapshot of the CassIAS GUI interface The interface
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