ROSAT Status Report #57:
May 6, 1993
ROSAT STATUS REPORT #57-redistribution of MPE bulletin #17
========================================================================= = = = ROSAT NEWS No. 17 --- 1-May-1993 = = = =-----------------------------------------------------------------------= = ROSAT Scientific Data Center at the = = Max-Planck Institut fuer Extraterrestrische Physik (MPE) = = Giessenbachstrasse, 8046 Garching, FRG = =-----------------------------------------------------------------------= = e-mail addresses (Uli Zimmermann): = = rosat_svc@mpe-garching.mpg.de (Internet) or = = MPE::ROSAT_SVC (SPAN) = = ROSAT Service Area read-access via anonymous ftp: = = ftp rosat_svc.mpe-garching.mpg.de user: anonymous = =-----------------------------------------------------------------------= = XUV Center: 29382::GXUVDC or GXUVDC@AIT.PHYSIK.UNI-TUEBINGEN.DE = ========================================================================= ======================================== ROSAT SERVICE AREA - NEW NETWORK ADDRESS =========================================
On May 1, 1993 the ROSAT Service Area was moved to its new location on the MPE UNIX Cluster.
In that area information is stored in ASCII files and ordered in different subdirectories. At present the following subdirectories (info groups) can be accessed:
archive information on public archive issues, lists etc. calibration instrument calibration related items exsas EXSAS/MIDAS bug reports, software updates etc. general general user info, e.g. ROSAT NEWS processing status and bug information from Standard Processing timeline mission timelines, not performed observations etc.
A file named contents.doc in each subdirectory contains a 1-line explanation of the different files present and also reports the time of the last update.
Users outside the institute can retrieve information from the area via an anonymous ftp account (access via SPAN or interactive login's are not possible), e.g.:
> ftp rosat_svc.mpe-garching.mpg.de user is anonymous
as password enter your last name
- help
- read help on ftp commands
- get contents.doc /dev/tty
- list available subdirectories (info items) on your terminal (on non-ULTRIX systems the pathname /dev/tty may be different)
- cd general
- change to subdirectory general
- get help.doc /dev/tty
- read general help info
- cd ../calibration
- change to directory calibration
- get contents.doc /dev/tty
- list contents file
- get ao2.timeline
- copy file ao2.timeline to your directory
- bye
- close the ftp session
Users at MPE can access the different directories in the ROSAT Service Area also via the 'info' system.
SATELLITE AND INSTRUMENT STATUS
The changes of the on-board software to enable the utilization of the WFC startracker for active attitude control were completed in April 1993. Software had to be modified in three subsystems, the AMCS, the DHS (central data handling system) and the WFC. The new WFC and DHS software has been tested in orbit and is now running continuously. Because of the limited memory, the new AMCS software can only run alternatively to the current mode and has therefore been tested only at the GSOC simulator. In case of a complete failure of startracker 1, the WFC-STC mode could be enabled within a few days. For operational reasons we, however, expect a substantial loss of observing efficiency. A slightly degraded accuracy is also expected.
The malfunction of STC 1 could be traced to a failure in the conventional RAM area. In principle this failure is similar to the cause of the complete loss of STC 2 in autumn 1990, where however a much more vital memory cell was lost, which rendered STC 2 unusable. The STC 1 anomaly has stabilized at a rather lower failure rate than observed in January/February, corresponding on average to a 5-10 percent loss of observing time.
The cause of our residual static and dynamic attitude reconstruction errors of roughly 5" for both PSPC and HRI is still not understood. Investigations by MBB, GSOC and MPE demonstrated startracker errors larger than anticipated which could be understood in terms of systematic errors in the STC ground calibration. Proposals for improvements for the attitude reconstruction software have been made and are already partially incorporated. The magnitude and characteristics of these stratracker errors are, however, not sufficient to explain the observed effects. A study of systematic errors in the XRT position readout is under way.
MISSION PLANNING
The ROSAT IUC (International User Commitee) had a 2 day meeting at MPE on April 29 and 30 and finalised the list of accepted AO-4 proposals. The AO-4 mission timeline for the PSPC observing period starting on June 15, will be produced in the course of the next few weeks and will then be accessible from the ROSAT Service Area.
A list of all proposals that passed the national and international selection phases will be available from the ROSAT Service Area (subdirectory timeline, file ao4.accepted) on May 7.
PROCESSING
It has recently been detected that the event screening applied during the Standard Processing in some cases may be in error (in a few extreme cases full OBI's have been screened off). The problem has been understood and is under repair. It should be kept in mind that no photons got lost. All rejected events are still available in the rejected event file. We are currently working on defining rules along which users should be able to identify and (hopefully) correct the affected datasets.
COMPUTER HARDWARE
Due to a total breakdown of the air condition in our computer center (still not yet repaired) the Data Center had to turn off from time to time some of the computers to prevent overheating. Therefore during the last month both the availability of the mailing facility and the access to the ROSAT Service Area were affected. Both have now been moved to the UNIX environment.
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