|
ABRIXAS, an Imaging Telescope for an
X-ray All-Sky Survey in the 0.5-10 keV Band
|
Request for Observation of the Satellite ABRIXAS (NORAD Number 25721)
The scientific institutes involved in the astronomical X-ray
satellite ABRIXAS ask for further observations of the satellite.
In particular, the interest is directed to the light variations
and eventually flashes from directly reflected sun light.
The aim is to determine the rotation behaviour of ABRIXAS.
Video observations are potentially very useful to record the
possibly faint periodic light variations.
Background:
Because of the failure of the batteries ABRIXAS is in a severe
situation; the knowledge about its rotation can be of great
importance for the revive planned for the next weeks since
it is essential to reestablish the contact to the satellite
and send commands at the right time.
In addition to the optical observations information from
radar measurements are now available.
The analysis suggests that the satellite is rotating around the axis
perpendicular to the solar panel with a period between 170 and 200
seconds. It is expected that the period will slowly increase.
However, the orientation of the rotation axis is unknown.
Hints for observations:
Apart from the solar panel itself reflections can occur at the edges
of the solar panel array and at the inner side of the radiator's
thermal baffle. The satellite is almost completely wrapped in a
diffusely reflecting white MLI foil. Because of the elongated shape
of ABRIXAS some variations of the satellite's brightness are expected
within each rotation period.
The current orbit data can be taken directly from
NORAD or from
GSOC
Many thanks to all satellite observers
which have already sent us their results! The analysis of these
data is going on...
Light curves from Paul D. Maley
(latitude 29.6049 north, longitude 95.1086 west, elevation 6 m)
obtained on 19-May-1999 and 10-Jun-1999, respectively
