| 1 | import os |
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| 2 | import math |
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| 3 | from asap import scantable |
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| 4 | from asap import merge |
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| 5 | from asap import fitter |
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| 6 | from asap import selector |
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| 7 | from asap import rcParams |
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| 8 | |
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| 9 | def _import_data(data): |
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| 10 | if not hasattr(data, "__len__"): |
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| 11 | if isinstance(data, scantable): |
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| 12 | return data |
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| 13 | elif isinstance(data, str): |
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| 14 | return scantable(data) |
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| 15 | tables = [] |
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| 16 | for d in data: |
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| 17 | if isinstance(d, scantable): |
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| 18 | tables.append(d) |
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| 19 | elif isinstance(d, str): |
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| 20 | if os.path.exists(d): |
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| 21 | tables.append(scantable(d)) |
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| 22 | else: |
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| 23 | raise IOError("Data file doesn't exists") |
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| 24 | else: |
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| 25 | raise TypeError("data is not a scantable or valid file") |
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| 26 | return merge(tables) |
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| 27 | |
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| 28 | def skydip(data, averagepol=True, tsky=300., plot=False): |
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| 29 | """Determine the opacity from a set of 'skydip' obervations. |
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| 30 | This can be any set of observations over a range of elevations, |
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| 31 | but will ususally be a dedicated (set of) scan(s). |
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| 32 | Return a list of 'n' opacities for 'n' IFs. In case of averagepol |
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| 33 | being 'False' a list of 'n*m' elements where 'm' is the number of |
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| 34 | polarisations, e.g. |
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| 35 | nIF = 3, nPol = 2 => [if0pol0, if0pol1, if1pol0, if1pol1, if2pol0, if2pol1] |
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| 36 | |
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| 37 | The opacity is determined by fitting a first order polynomial to: |
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| 38 | |
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| 39 | |
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| 40 | Tsys(airmass) = p0 + airmass*p1 |
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| 41 | |
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| 42 | where |
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| 43 | |
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| 44 | airmass = 1/sin(elevation) |
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| 45 | |
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| 46 | tau = p1/Tsky |
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| 47 | |
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| 48 | Parameters: |
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| 49 | data: a list of file names or scantables or a single |
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| 50 | file name or scantable. |
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| 51 | averagepol: Return the average of the opacities for the polarisations |
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| 52 | This might be useful to set to 'False' if one polarisation |
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| 53 | is corrupted (Mopra). If set to 'False', an opacity value |
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| 54 | per polarisation is returned. |
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| 55 | tksy: The sky temperature (default 300.0K). This might |
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| 56 | be read from the data in the future. |
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| 57 | plot: Plot each fit (airmass vs. Tsys). Default is 'False' |
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| 58 | """ |
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| 59 | scan = _import_data(data) |
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| 60 | f = fitter() |
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| 61 | f.set_function(poly=1) |
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| 62 | sel = selector() |
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| 63 | basesel = scan.get_selection() |
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| 64 | inos = scan.getifnos() |
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| 65 | pnos = scan.getpolnos() |
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| 66 | opacities = [] |
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| 67 | for ino in inos: |
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| 68 | sel.set_ifs(ino) |
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| 69 | opacity = [] |
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| 70 | for pno in pnos: |
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| 71 | sel.set_polarisations(pno) |
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| 72 | scan.set_selection(basesel+sel) |
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| 73 | tsys = scan.get_tsys() |
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| 74 | elev = scan.get_elevation() |
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| 75 | airmass = [ 1./math.sin(i) for i in elev ] |
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| 76 | f.set_data(airmass, tsys) |
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| 77 | f.fit() |
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| 78 | if plot: |
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| 79 | f.plot(residual=True, plotparms=True) |
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| 80 | raw_input("Hit <return> for next fit...") |
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| 81 | params = f.get_parameters()["params"] |
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| 82 | opacity.append(params[1]/tsky) |
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| 83 | if averagepol: |
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| 84 | opacities.append(sum(opacity)/len(opacity)) |
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| 85 | else: |
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| 86 | opacities += opacity |
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| 87 | sel.reset() |
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| 88 | scan.set_selection(basesel) |
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| 89 | return opacities |
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