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1. and plotted for inspection 3 8 Fitting a Baseline Polynomial A polynomial of order 1 5 may be fitted to the currently displayed scan Click on the Fit Baseline button to display the Baseline Fitting Dialog The x axis of the plotted spectrum will change from velocity to channel number The baseline is fitted using two baseline boxes regions of the spectrum absent of any spectral lines Choose two baseline boxes from the plot and enter in their channel ranges in the fields provided eg 1075 1375 and 1698 1998 Be wary of syntax mistakes here as SPC will return rubish results if you enter a text character by mistake Choose the order of polynomial to fit 1 5 from the menu at the top of the dialog box Click on Fit to see the effect of your chosen fit If you wish to try again with new settings simply click Revert to return to the original scan When you are happy with the fit click Apply changes will be saved to the scan and the dialog box will close Cancel aborts any changes made and exits from the dialog box 3 9 Zeroing Channels Occasionally it may be necessary to set some chanels in an individual scan to zero particiularly at the edges of the bandpass Click on the Zero Channels button to bring up the Zero Channels Dialog The x axis of the plotted spectrum will change from velocity to channel number Enter the range of channels to be zeroed in the fields provided and click Zero to test Revert returns to the original scan When
2. you are happy with the result click Apply changes will be saved to the scan and the dialog box will close Cancel aborts any changes made and exits from the dialog box Note To achieve good results with this tool it may be necessary to fit a baseline to the scan in quiestion first 3 10 Shifting the Velocity Scale When observing molecules with multiple transitions it may be necessary to shift the velocity scale on the scans so that the zero position corresponds to a particular line It is also possible that the wrong frequency was centred in the bandpass due to errors while observing or otherwise Click on the Shift Velocity button to display the Offset Velocity Dialog The current zero velocity frequency is displayed as requested at the telescope and uncorrected for VLSR of source If this frequency is different from the desired frequency simply enter in the desired zero velocity frequency and click Calculate to compute the necessary velocity offset The calculated offset will appear in the Velocity Offset field Alternatively the desired offset may be entered manually The Test button shifts the scale by the desired amount Revert returns to the last scan Apply causes the changes to be saved to the scan and exits the dialog box Cancel aborts any changes made and exits the dialog box 3 10 Saving Results The currently displayed scan indicated by the green box may be saved at any time simply by clicking on the Save File button In the fi
3. D ata F rom M User Manual by Cormac Purcell 31 10 2003 Contents 1 Introduction What is DFM 2 The User Interface 2 1 The Load Panel 2 2 The Information Panel 2 3 The Scan Panel 2 4 The Message Panel 2 5 The Action Panel 2 6 The Save Panel 3 Reducing Position Switched Data 3 1 Preliminary Information Register Usage 3 2 The Settings Dialog 3 3 Loading a Data File 3 4 Examining Data 3 5 Averaging Single Polarisation Data 3 6 Changing Polarisation 3 7 Averaging Dual Polarisation Data 3 8 Fitting a Baseline Polynomial 3 9 Zeroing Channels 3 10 Shifting the Velocity Scale 3 11 Saving Results 3 12 Quitting 1 Introduction What is DFM DFM is a GUI interface to SPC the spectral line reduction program used to process Mopra and Parkes data It is designed to enable the novice user to quickly and easily reduce dual polarisation position switched data into a format usable by other programs such as CLASS and XS DFM contains the following features Automatically forms a quotent from signal and reference spectra on loading data Supports the following modes of position switching ref sig sig ref ref sig sig ref sig ref ref sig Switches data to the LSR K reference frame on load Allows seperate and independent reduction of both polarisation quadrants Allows the user to inspect and flag bad scans in one click Aligns and averages scans in velocity space weighted by Integration Time Tsys Correctly averages polari
4. Message Panel Directory containing input file Input file name with extention Displays the settings menu Type of file being read e Accumulate individual integrations from a single position rpf files only e Correct for the Parkes Scaling Error Form a quotient from Signal Reference e Order of the scans in the file Ref Sig Load the file into the registry Switches to the LSR K reference frame Form the quotients and plot the 1 scan Source Name of the current scan Date of observation Frequency of Polarisation A 1 Quadrant Bandwidth of Polarisation A RA in J2000 Dec in J2000 Current scan register displayed Selectable list of scans e Select or de select individual scans to average together e Clicked scans will be displayed and the values in the Information Panel will update accordingly Blue Box 2 5 The Action Panel Pol A B Sel amp Average AvA amp B Fit Baseline Zero Channels Shift Vel 2 6 The Save Panel Dir File File Type Save Quit Messages and feedback Error and confirmation messages Tsys and Integration Time for the current scan Toggles between Polarisation A and B Aligns and averages the selected scans in the current polarisation Saves the result and remembers the scans selected Averages the results from Sel amp Average on Pol A and Pol B Only available if Pol A and Pol B have been averaged Displays the Fit Baseline Dia
5. an number causes it to be displayed in the PGPLOT window and selects it for averaging highlighted in colour Clicking a highlighted scan dedelects it The green box contains the number of the currently displayed scan 3 5 Averaging Single Polarisation Data Data from a single polarisation may be averaged together by clicking the Sel amp Average button Highlighted scans are aligned in velocity space and then averaged together weighted by Int Time Tsys The result is stored in reserved register and plotted for inspection The selections made may be specific to a single polarisation and both the result and the scans selected for averaging are remembered by DFM 3 6 Changing Polarisation You may toggle between polarisation at any time by clicking on the button labeled Pol A Pol B If you have already averaged scans from one polarisation the result will be displayed upon returning to that polarisation additionally the individual scans selected for averaging will be retained 3 7 Averaging Dual Polarisation Data Dual polarisation data may be combined by first averaging data from each polarisation individually and then combining the two results When both Pol A and Pol B data has been averaged using the Sel amp Av button the Av A amp B button will become active Clicking this button averages the Pol A and Pol B data together weighted by Int Time Tsys The resultant scan is stored in quadrant 1 Pol A of a reserved register
6. eld labeled Dir enter the full path to the directory you wish to write files to You must include the trailing as in the load panel The File field contains the prefix of the file to be saved by default this is the source name as read from the input file Select your desired file type from the File Type menu Supported types are SD Fits and Fits and Postscript plots Click on Save Files to write the file Note it is not possible to overwrite files of the same name 3 11 Quitting To exit the program click the Quit button The choices made in the Settings dialog will be saved to a text file named dfm_settings in your home directory DFM will read this file on the next startup
7. log Fit a polynomial to the baseline order 1 5 Displays the Zero Channels Dialog Zero a selected range of channels Displays the Shift Velocity Dialog Calculates a velocity shift based on a difference in zero velocity frequency and a user specified frequency Velocity shift can be specified manually Directory to write out to File name prefix Choose format of output file sdf fits ps Save a the currently displayed scan using a the options specified above End the program and save the settings last used 3 Reducing Position Switched Data 3 1 Preliminary Information Register Usage SPC has a maximum of 256 registers which may be used to store scans DFM reserves six registers for its own use meaning that files containing more than 250 individual positions Sig or Ref will need to be split In an individual scan Pol A data is stored in Quadrant 1 while Pol B data is stored in Quadrant 2 If a data file contains n scans corresponding to n individual positions then the 6 registers immediately after the nth scan will be used in the reduction process The usage is allcoated as so Register Usage N Last scan in the data set N 1 Average of selected Pol A scans Quad 1 N 2 Average of selected Pol B scans Quad 2 N 3 Average of Pol A amp B scans Quad 1 N 4 Copy of Pol B scans copied to Quad 1 Save N 5 Temporary Scratch Register N 6 Copy of Pol B scans copied to Quad 1 A
8. ome directory and read each time the program is started When finished click OK to dismiss the Settings Dialog and save the settings 3 3 Loading a Data File After configuring the load settings as above type in the full directory path to your data directory in the field labeled Dir It is necessary to enter the last in the path eg home crp data Type in the full file name including extention in the field labeled File and click the Load button The data file will be read and loaded into memory using the options specified in the Settings dialog On load the following tasks are performed Accumulate optional RPFits files only Concatenate all adjacent scans beloging to a single position Rvel Switch all scans to the LSR K reference frame Scale Err optional If the observations were taken before 05 09 2002 correct the amplitude of all the scans for the Parkes Scaling Error Quotient optional Form the quotient based on the observing scheme specified in the settings dialog The algorithm used is Q TrerS R Tsig where Tret and Tsig are the system temperatures of the reference and signal spectra Q S R are the quotient signal and reference spectra A list of the scan numbers loaded appears in the Scan Selection Panel and the first scan is displayed in the PGPLOT window 3 4 Examining Data The scan selection panel contains a list of all scans loaded into memory in the current polarisation Clicking on a sc
9. sation A and B together using correct header data Provides an interface fit polynomials to scan baselines with the option of accepting or rejecting the results in a single click Allows the user to zero portions of the any scan Allows the user to shift the velocity scale on any scan based on the desired zero velocity frequency Supports input of both rpf and sdf format data Supports output in sdf fits and ps formats Corrects for the Parkes Scaling Error automatically for data prior to 05 09 02 All of the above tasks may be performed manualy on the command line using spc however this would be a long and involved process DFM automatically compensates for quirks in SPC that might result in errors in the reduced data should the user not be aware of them and take the appropriate steps 2 The User Interface Dir fhome crp data dtest Settings Load Src 16361 0627_ Date 2003 07 06 Freq 86 629558 BW 63 9356 RA 16425307 DEC 04 37 34 5 oll sal_ad Dir fnome crp data dtest File 18361 0627 sdf file 12 gt Tsys 185 4000 Int 110 00 17 gt Tsys 185 4000 Int 330 00 17 gt Tsys 185 4000 Int 330 00 PaA Fit Baseline Sel amp Av Zero Channels Shift Vel 2 1 The Load Panel Dir File Settings Load 2 2 The Information Panel Src Date Freq BW RA DEC 2 3 The Scan Panel Green Box Long Box 2 4 The
10. v A amp B 3 2 The Settings Dialog Before loading a data file it is necessary to tailor the file loading options to the data Click on the Settings button to display the settings dialog Choose the file type both sdfits and rpfits are supported Depending on the schedule file used during the observations adjacent scans may need to be accumulated together This will be the case if the telscope dumped data to the file more than once per pointing Choose Auto if you want to accumulate the individual integrations or straight otherwise Note this option is only available when loading raw RPFits files Data taken before 5 September 2002 is affected by a scaling error introduced in the Telescope Control Software The amplitude of the Pol A data was multiplied by 1 51 and Pol B by 1 73 before being written to the file Selecting the TCS Scaling Error Correction checkbutton implements a routine that removes these scaling factors from each scan based on the date of observation If you are loading previously corrected data from an sdf file you should turn this option off You can choose to form quotient scans from the reference and signal positions at load time Four observation schemes are supported at the present time 1 Reference Signal 2 Signal Reference 3 Reference Signal Signal Reference 4 Signal Reference Reference Signal These settings will be retained in a text file called dfm_settings in your h

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