RA Scan Stability

RA Scan Stability from 970521n

R. Cutri - IPAC


The deviations from constant of-date RA during 6 degree scans are evaluated for 10 scans on 970521 UT. Scans 013-022 covered the same region in the Coma Cluster of galaxies, and were taken consecutively in alternating directions.

The PostScript files below contain plots that show the differences, in arc-seconds, between the start of scan RA reported in the telescope telemetry and the reconstructed frame centers for each of the 272 frames in the scan. The nominal start of scan and frame center positions were precessed from J2000 to 1997.39 equinox before calculating the differences. The direction of each scan is indicated following the frame number. Note that the scales on all of the plots are identical, except the for the last - scan 022. For scan 22, the vertical scale is shifted by -5".

  • RA drift versus declination (i.e. frame number) for scans 013-016 on 970521 UT
  • RA drift versus declination (i.e. frame number) for scans 017-020 on 970521 UT
  • RA drift versus declination (i.e. frame number) for scans 021-022 on 970521 UT