| [1636] | 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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