From SCHUEHLE@sumop1.nascom.nasa.gov Tue Nov 18 16:41:30 2003
Date: Thu, 20 Mar 1997 16:16:17 GMT
From: SCHUEHLE@sumop1.nascom.nasa.gov
Reply-To: sumer-soft@esa.nascom.nasa.gov
To: sumer-soft@esa.nascom.nasa.gov
Cc: SCHUEHLE@sumop1.nascom.nasa.gov
Subject: SUMER-SOFT: pointing calibration by Sun spot observation 12. March 97


      Dear Collegues,

      Using a small Sun spot related to the active region that crossed the
      central meridian on March 12., we have taken the opportunity to use the
      SUMER Rear Slit Camera to take images while the spot moved across the
      slit by the rotation of the Sun.  The composite image of the
      RSC-exposures gives a good map of the Sun spot with a contrast of >30%.
      The image was used to relate to the MDI white light and Mees
      Observatory white light images of the same day to determine the
      absolute position of the SUMER slit at this time.  The result is that
      the SUMER position on 12 March 1997 at 10:00UT was +7 arcsec (+-2.4).

      We hope that this type of measurement can be repeated at another
      occasion to get more information of the stability of the pointing and,
      in particular, to determine the position after the slit has been
      displaced from the central meridian to a new location.


      GSFC, 20. March 1997
      Udo Schuehle, Phil Judge and Oivind Wikstol