| 1 | #include <casa/aips.h>
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| 2 | #include <casa/iostream.h>
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| 3 | #include <casa/iomanip.h>
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| 4 |
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| 5 | #include <measures/Measures.h>
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| 6 | #include <measures/Measures/MeasFrame.h>
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| 7 | #include <measures/Measures/MCEpoch.h>
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| 8 | #include <measures/Measures/MCDirection.h>
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| 9 | #include <measures/Measures/MCPosition.h>
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| 10 | #include <measures/Measures/MCFrequency.h>
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| 11 | #include <measures/Measures/MCRadialVelocity.h>
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| 12 | #include <measures/Measures/MCDoppler.h>
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| 13 |
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| 14 |
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| 15 | #include <casa/Exceptions/Error.h>
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| 16 |
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| 17 | using namespace casa;
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| 18 |
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| 19 | int main() {
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| 20 | try {
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| 21 | // Observed peak topocentric frequencies of the maser at 3 given epochs
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| 22 | Vector<Double> freqs(3);
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| 23 | freqs(0) = 4.76503417969;
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| 24 | freqs(1) = 4.76469824219;
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| 25 | freqs(2) = 4.76493066406;
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| 26 | // epochs of observations (mjd)
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| 27 | Vector<Double> epochs(3);
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| 28 | epochs(0) = 54468.493923611109;
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| 29 | epochs(1) = 54542.278935185182;
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| 30 | epochs(2) = 54614.149143518516;
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| 31 |
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| 32 | // rest frequency in Hz (needed for velocity-based conversion)
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| 33 | const Double restfreq = 4.765562e9;
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| 34 |
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| 35 | // buffer for LSRK frequencies and velocity
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| 36 | Vector<Double> outfreqs(3);
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| 37 | Vector<Double> outvels(3);
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| 38 | Vector<Double> outfreqs_viavel(3);
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| 39 |
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| 40 |
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| 41 | // The frequency axis increment in Hz, given here just to show the error in terms of the
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| 42 | // spectral channel width. The main reason for this is to give a right feeling how big the
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| 43 | // error is. All conversions are done for single frequencies.
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| 44 | Double deltaf = 976.5625;
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| 45 |
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| 46 | // Hobart using VLBI position
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| 47 | MPosition obs(MVPosition(-3950236.7341,
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| 48 | 2522347.553,
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| 49 | -4311562.5434),MPosition::ITRF);
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| 50 |
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| 51 | // Monr2 maser at 4.7 GHz checked against literature
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| 52 | MDirection coord(Quantity(1.6048229750035694,"rad"),
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| 53 | Quantity(-0.11139370025381365,"rad"),
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| 54 | MDirection::J2000);
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| 55 |
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| 56 | for (uInt i=0; i < epochs.nelements(); ++i) {
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| 57 | //UTC epoch varies
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| 58 | MEpoch epo0(Quantity(epochs(i),"d"));
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| 59 | MeasFrame frame(obs,coord,epo0);
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| 60 | MFrequency mf0(Quantity(freqs(i), "GHz"), MFrequency::TOPO);
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| 61 |
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| 62 | // convert TOPO frequency to LSRK
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| 63 | MFrequency mfout0 = MFrequency::Convert(mf0,
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| 64 | MFrequency::Ref(MFrequency::LSRK,
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| 65 | frame))();
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| 66 | outfreqs[i] = mfout0.get(Unit("Hz")).getValue();
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| 67 |
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| 68 | // convert TOPO frequency to TOPO velocity
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| 69 | MRadialVelocity mv0 = MRadialVelocity::fromDoppler(mf0.toDoppler(restfreq),MRadialVelocity::TOPO);
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| 70 |
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| 71 | // convert TOPO velocity to LSRK velocity
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| 72 | MRadialVelocity mvout0 = MRadialVelocity::Convert(mv0,
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| 73 | MRadialVelocity::Ref(MRadialVelocity::LSRK, frame))();
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| 74 | outvels[i] = mvout0.get("km/s").getValue();
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| 75 |
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| 76 | // convert LSRK velocity to LSRK frequency
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| 77 | mfout0 = MFrequency::fromDoppler(mvout0.toDoppler(), restfreq, MFrequency::LSRK);
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| 78 | outfreqs_viavel[i] = mfout0.get("Hz").getValue();
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| 79 |
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| 80 | }
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| 81 | cout << "In freqs: " << setprecision(10) << freqs << endl;
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| 82 | cout << "Out freqs: " << setprecision(10) << outfreqs << endl;
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| 83 | cout << "... via velocity: " << setprecision(10) << outfreqs_viavel << endl;
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| 84 | cout << "Out vel: " << setprecision(10) << outvels << endl;
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| 85 |
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| 86 |
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| 87 | // This should be < 1.0
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| 88 | cout << "Difference 2-0" << endl;
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| 89 | cout << "LSR via freq (chan): " << (outfreqs[2] - outfreqs[0])/deltaf << endl;
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| 90 | cout << "LSR via vel (chan): " << (outfreqs_viavel[2] - outfreqs_viavel[0])/deltaf << endl;
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| 91 | cout << "LSR velocities (km/s): " << (outvels[2] - outvels[0]) << endl;
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| 92 | cout << "TOPO (in): " << (freqs[2] - freqs[0])*1e9/deltaf << endl;
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| 93 | cout << "Difference 1-0" << endl;
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| 94 | cout << "LSR via freq (chan): " << (outfreqs[1] - outfreqs[0])/deltaf << endl;
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| 95 | cout << "LSR via vel (chan): " << (outfreqs_viavel[1] - outfreqs_viavel[0])/deltaf << endl;
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| 96 | cout << "LSR velocities (km/s): " << (outvels[1] - outvels[0]) << endl;
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| 97 | cout << "TOPO (in): " << (freqs[1] - freqs[0])*1e9/deltaf << endl;
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| 98 | } catch (AipsError &e) {
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| 99 | cout << e.what() << endl;
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| 100 | }
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| 101 | return 0;
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| 102 | }
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