ROSAT Status Report #116 Feb 6 1995 ========================================================================= = = = ROSAT NEWS No. 35 --- 1-Feb-1995 = = = =-----------------------------------------------------------------------= = ROSAT Scientific Data Center at the = = Max-Planck-Institut fuer Extraterrestrische Physik (MPE) = = Postfach 1603, D-85740 Garching, Germany = =-----------------------------------------------------------------------= = e-mail addresses (Uli Zimmermann): = = rosat_svc@mpe-garching.mpg.de (Internet) or MPE::ROSAT_SVC (SPAN) = = ROSAT Service Area (including ROSAT Data Archive): = = ftp rosat_svc.mpe-garching.mpg.de user: anonymous = = WWW address: http://wave.xray.mpe.mpg.de/rosat/ = = interactive account (including ROSAT Result Archive): = = telnet xray.mpe-garching.mpg.de user: xray no password = =-----------------------------------------------------------------------= = XUV Center: 29382::GXUVDC or GXUVDC@AIT.PHYSIK.UNI-TUEBINGEN.DE = = WFC Archive access via telnet/ftp ait.physik.uni-tuebingen.de = = user: xuv (password: xuv_archive) = ========================================================================= SATELLITE STATUS/MISSION PLANNING ================================= An imperfection in the mission planning procedure was identified which led to the scheduling of 'impossible' observing slots implying a loss on the order of 5 % of the total and 13 % of the time critical observing time. This imperfection is related to the constrained mobility of the satellite which requires sun sensor information for any slew or target acquisition procedure. While in general the mission planning accounts for this constraint, and does not foresee any target changes on the night side of the satellite orbit, there is still one particular case in which 'impossible' observing slots were scheduled. This case can be characterized as follows: 1) a target was previously acquired on the day side; 2) it then underwent a temporary earth block after which its observation was to be continued (with no target changes inbetween); 3) the earth block either ended after the night began or so shortly before the beginning of the night that no re-acquisition was possible on the day side. In such cases observing slots after the end of the earth block erroneously appeared in the mission timeline, but the targets could not be acquired, and the slots were not used. This situation affects time- critical observations more strongly than non-time critical ones for which the optimized mission planning procedure is likely to avoid earth blocks anyway. In the forthcoming mission timeline for the second part of AO5 (beginning in April 1995) this special case will be treated properly, and we expect an overall increase in observing efficiency. However, we stress that these 'impossible' slots are a result of the degraded attitude control system and will remain unavailable. This is especially important for time-critical observations which have become more difficult to carry out. If in the future you will find other observations scheduled at the time-critical period you asked for in your proposal, it will be because there were 'impossible' slots for your target which were used otherwise. EXSAS ===== Release 95JAN of the EXSAS software has been tested within the MIDAS 94NOV environment for the UNIX systems on AXP (OSF), HP, IBM, SUN, SUN Solaris, and DECstations (ULTRIX). The software may be copied from the ROSAT Service Area. Tests on the VMS and the LINUX systems are underway. ====================== end of ROSAT NEWS ================================