| About ROSAT |
ROSAT Home Page | ROSAT Images |
|---|
[Aschenbach
et al.1985], [ROSAT AO-21991, NRA 91-OSSA-31991],
[Voges1992, Snowden and
Schmitt1990]
During the six-month survey phase, nearly the entire sky was scanned
in 2 
(5 
for the WFC) strips centered on great circles
running through the ecliptic poles, roughly perpendicular to the
Earth-Sun line.
The rotation period was synchronized to the orbital period by the scan
control law in such a manner that no Earth occultations occurred
and the zenith angle was minimized.
The nominal scan rate was 
360 
of ecliptic latitude per
satellite orbit, and the nominal progression rate of 0.986 
per day, which was increased to 
1.46 
per day
at the end of the survey.
The PSPC (with a 2 
FOV) was in the focal plane
of the XRT during the all-sky survey.
The S1 and S2 filters were used alternately by the
WFC (5 
FOV) in order to obtain 2 XUV colours
in the 60-200 Å band.
The last week of the scheduled survey phase was lost due to the solar slew on 1991 January 25 described in App. A. However, the unobserved region was surveyed between 1991 February 23-25 and 1991 August 3-13 during breaks in the AO-1 mission phase. Figure 1.3 is an Aitoff projection of the celestial sphere showing the (logarithmic) exposure time of the ROSAT all-sky survey.