| 1 | ================================================ |
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| 2 | Tutorial 2 â Data Reduction for multiple spectra |
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| 3 | ================================================ |
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| 4 | |
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| 5 | |
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| 6 | .. sectionauthor:: Kate Brooks |
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| 7 | |
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| 8 | **Main goal:** Handle multiple Spectral windows (IFs) and plot spectral-line catalogues |
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| 9 | |
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| 10 | |
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| 11 | Files |
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| 12 | ----- |
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| 13 | |
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| 14 | * 2006-07-09_1431-M168.rpf Data file (63 Mb) |
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| 15 | |
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| 16 | * 3mm.txt Emission line catalogue |
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| 17 | |
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| 18 | * QuickData.py Data Reduction GUI (by Cormac Purcell) |
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| 19 | |
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| 20 | Data Log |
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| 21 | -------- |
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| 22 | |
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| 23 | * ON-OFF-OFF-ON Position switching mode with Mopra |
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| 24 | |
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| 25 | * 4 Scans (2 OFF and 2 ON) |
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| 26 | |
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| 27 | * 4 x 2-GH bands (IF 0, 1, 2, 3) |
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| 28 | |
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| 29 | Instructions |
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| 30 | ------------ |
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| 31 | |
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| 32 | 1. Work through the list of commands given in the text file to |
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| 33 | calibrate data taken with the Mopra telescope and identify the |
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| 34 | emission lines. Commands should be typed line-by-line into |
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| 35 | ASAP. Seek help from the tutors if there are any commands |
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| 36 | you donât understand. |
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| 37 | |
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| 38 | 2. The commands given in the text file are for 1 Mopra frequency |
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| 39 | band only (IF0). Now work on the other 3 bands and make a |
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| 40 | final plot showing all four frequency bands stitched together. |
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| 41 | |
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| 42 | 3. Now repeat the calibration steps using the Mopra Data |
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| 43 | Reduction GUI. This GUI has been created via a python script |
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| 44 | (QuickData.py). |
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| 45 | |
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| 46 | Commands |
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| 47 | -------- |
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| 48 | |
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| 49 | .. code-block:: python |
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| 50 | |
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| 51 | # Load data into memory and display short description |
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| 52 | s = scantable('2006-07-09_1431-M168.rpf') |
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| 53 | print s |
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| 54 | # Set the plotting mode |
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| 55 | plotter.set_mode(stacking='i', panelling='t') |
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| 56 | plotter.set_histogram() |
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| 57 | plotter.set_colours('black') |
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| 58 | plotter.set_linestyles('solid') |
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| 59 | # Plot all the raw data |
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| 60 | plotter.plot(s) |
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| 61 | # Form the quotient spectra |
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| 62 | q = s.auto_quotient() |
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| 63 | # Average all scans in time, weighting according to Tsys value |
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| 64 | av = q.average_time(weight='tsys') |
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| 65 | # Average the two polarisations together, weighting according to Tsys value |
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| 66 | iav = av.average_pol(weight='tsys') |
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| 67 | ### Work on IF0 only |
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| 68 | # Define a selector |
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| 69 | sel1 = selector() |
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| 70 | # Select the first IF for scantable 'iav' |
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| 71 | sel1.set_ifs(0) |
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| 72 | iav.set_selection(sel1) |
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| 73 | # Plot the first IF with x-axis in channel number |
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| 74 | iav.set_unit('channel') |
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| 75 | plotter.plot(iav) |
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| 76 | # Flag out the end channels |
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| 77 | msk1 = iav.create_mask([0,120]) |
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| 78 | iav.flag(msk1) |
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| 79 | msk1 = iav.create_mask([7900,8200]) |
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| 80 | iav.flag(msk1) |
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| 81 | # Redo the plot |
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| 82 | plotter.plot(iav) |
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| 83 | # Identify emission lines |
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| 84 | iav.set_unit('GHz') |
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| 85 | plotter.plot(iav) |
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| 86 | # Load in catalogue of emission lines and overlay on plot |
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| 87 | lc3 = linecatalog('3mm.txt') |
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| 88 | plotter.plot_lines(lc3,location='top',rotate=90,doppler=-45) |
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