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A standard recipe

So here are the steps for a standard astrometry reduction.

get_data,'2001-03-16.coh' (Read a CONSTRICTOR file with coherent integrations.)
hds_close
REDUCEBG DATADEFAULT BG (To make sure every scan has a back ground rate and set it to zero since we don't care about the visibility calibration.)
REDUCEPOINT DATAASTROMETRYPHASEEDIT (Flag all channels higher than 20 as well as the laser channel 11. Data after about May 2002 only need channel 12 of spectrometer 1 flagged. This is done automatically.)
flagphase,2,1,chan=indgen(16)+1 Optional flagging of baseline 1 in beam 2, in this example. This is needed if the same baseline occurs twice in the data. In the case of a reference baseline, the one in the first beam would be overwritten by the one in the second beam, and so on, in the dispersion correction procedure.
REDUCEPOINT DATAASTROMETRYPHASEWRAP (Unwrap the phases as a function of channel.)
REDUCEPOINT DATAASTROMETRYDISPCORR (Compute dispersion correction.)
REDUCEPOINT DATAASTROMETRYPLOT (Plot VACDELAY, i.e. the dispersion corrected delay relative to the predicted geometric delay and flag. Use PLOTAUTO. The reference station values are zero by definition.)
hds_open,'2001-03-16.inch' (Open INCHWORM file.)
get_metroconfig
get_motiongroup,1
hds_close
pivotfit. An optional step which fits siderostat pivot coordinates. RMS residuals should be on the order of a couple of microns. After this step, plotting ParXYZ corr. will display the residuals (see next step).
REDUCEINCH DATAPLOT. Plot azimuth versus elevation, connecting data points with lines. Smooth curves should be the result. This is a test whether proper siderostat models are loaded. Also plot ParX,Y,Z to look for outliers.
REDUCEINCH DATAINIT (For now, we plan on computing and applying the metrology correction after averaging, so we have to initialize the metrology correction to zero for the calibrated delays not to be flagged during averaging.)
average
inchav
CALIBRATEASTROMETRYMETROCORR (Compute and apply constant term and pivot corrections.)
CALIBRATEASTROMETRYSOLVE (Compute astrometric solutions)


next up previous contents
Next: Imaging simulations Up: Astrometry data reduction Previous: Metrology corrections   Contents
Christian Hummel 2009-10-20