Ra, Dec in fits headers


    The computation of the ra/dec J2000 for the fits headers was modified on 16sep04. The new format stores the ra and dec J2000 for each beam of the alfa array in crval2a, crval3a. The program is now interpolating the value in scramnet memory (returned from the telescope) to better align the header values with the data taken.  It is also possible to compute the ra,dec from the az,el value and the time stamp. The difference between the ra/dec in the header and the ra/dec computed from the encoders is shown in the plot below. The difference between the raEncoder and raFitsFile is jumping around by about 2 arc seconds.  The plot of the step size for each strip shows that this jumping is coming from fits data and not the encoder values. Since this was a drift scan, the step size should be constant at 15Asec/sec (i did not multiply by the cosine of the declination).

    The next step is to find the location of continuum sources in the drift scan and see how the positions come out.

processing: x101/040924/chkRaDec_a194623sep04.pro