Observations of Abrixas urgently needed

Michel Jacquesson (Michel.Jacquesson@wanadoo.fr)
Sun, 11 Jul 1999 21:10:35 +0200


   I received today a mail of K. Dennerl which forwarded another mail 
about Abrixas situation :

While the statement on the loss of Abrixas is correct from the science
point of view, it is somewhat different from the operational side.
Both, GSOC and OHB are continuing their daily(!) efforts to get into 
with Abrixas, and will do so for the next months at least until the next
full-Sun period in December 1999. Thus, it remains of immenent interest 
finally determine the rotation axis of Abrixas in order to determine
whether (once the rotation stopped) or not the solar panels will
point towards the Sun in December or not. Note that due to the main
momentum axis of the satellite there are only two stable locations
for Abrixas in absence of any attitude control, namely either point
towards the Sun, or anti-Sun.

  As people at AIP have made good progress in establishing a model of 
reflectivity of Abrixas in order to describe the observed light curve,
further observations are urgently needed to follow the change of the
rotation axis with time. Therefore, it is certainly too early at this
moment to stop optical observations. (As a matter of fact we have to
rely on optical observatiosn only, since radio observations at Haystack
seem nearly impossible to get.)

405' E   4936' N