ROSAT Status Report #1:
Goddard Guest Observer Facility ROSAT Status Report 3/21/91
Satellite:
- ROSAT had some problems in the early part of the pointed phase
comprising two days in February when the satellite lost attitude.
- Only the WFC has had problems this past week, as the sun shutter
was put in twice when the AMCS didn't update (the main extra safety
thing put in since January).These two interruptions only caused 5 and
1 hour delays to the XRT pointings
- We are now getting daily attitude protocols from the Max Plank Institute for Extraterrestrial Physics MPE).
SASS:
The following information is intended as the first bulletin on the progress of the Standard Analysis Software System (SASS). For those of you who don't know, SASS will do preliminary processing of your observations and produce reasonable data products. Updates to this bulletin will be posted on a weekly basis in an effort to keep the ROSAT investigators informed. The United States ROSAT Science Data Center (USRSDC) received and installed Version 4.0 of the (SASS) the week of Jan. 21, 1991. Version 4.0 was intended to be the official production version. At receipt of 4.0, the SASS team began a thorough testing of the system. PCV phase pointed data has been used for end-to-end testing and to check all system functions. An exhaustive comparison of ROSAT day 54 output has been used as a baseline between the U.S. and German data centers. Also, there have been some format problems with the Master Data Record (MDR) tapes that have been discovered during this testing. The USRSDC has been checking out all the other PCV (performance calibration and verification) phase MDR tapes and reporting errors to the German Space Operations Center (GSOC). As a result of this testing and similar efforts at MPE, a new version of SASS is currently being developed. SAO has sent the updated High Resolution Imager (HRI) software to MPE. This software will then be integrated into the revised SASS in approximately one week. The expected arrival time of this new version to the USRSDC is the first week of April. On the same date, the USRSDC also expects to receive the first short-term mission timeline (SMTL). The SASS system uses the SMTL to merge observation intervals (OBIs) into a sequence (PI observation) and to identify bad OBIs (wrong RA, DEC, etc.). The SMTL must be received in order to process any A01 pointed phase data. Once these two items are received from MPE, the SASS team anticipates an additional month's work to install, shakeout, and end-to-end test the new version. Based on this schedule, the USRSDC hopes to deliver first processed data in early May.Level 2 data analysis software status:
PROS:
The National Optical Astronomy Observatories (NOAO) andImage Reduction and Analysis Facility (IRAF) was developed to provide many of the features needed to analyze generic astronomical data. The Post Reduction Offline Software (PROS) is a portable X-ray analysis software system which runs under IRAF. It is tailored to be well suited to the analysis of X-ray data and it is expected that the majority of the ROSAT data analyzed at Goddard will be under PROS. fulfillThe ROSAT flight version of PROS is being installed at Goddard Space Flight Center this week. End to end testing of the SASS products with this new version of PROS will take place March 25-29th. This version of PROS will have updated software packages for imaging, timing and spectral analysis and will the data reduction requirements of most observers.
XANADU:
XANADU is a suite of X-ray data analyzing programs which were originally written to run under vax VMS. The programs utilize QDP plotting routines and provide a flexible and friendly environment for X-ray data analysis. Many users will be familiar with this analysis system as it is integrated into the EXOSAT database.XIMAGE can read those files containing the photon events and the good time intervals for both the HRI and PSPC files which come out of the SASS (pipeline) processing software. A program (external to ximage) can convert from 3d format to .toe format (ie a format that XIMAGE can read). Another program to create the required .pdf files will be implemented soon. A reader for the 3d format will be inserted into XIMAGE as well, enabling the pipeline FITS files to be read directly into XIMAGE.
You can display an hri or pspc image using XIMAGE, and run the the XIMAGE routines 'detect' and 'sosta'. The first searches the field for sources, the second does a statistical analysis. You can extract a count rate under the following assumptions:
uniform background, 100% exposure on each pixel and using a psf which is energy and position independent. The count rate estimated in this way is subject to an uncertainty of 20-30%. The positions should be accurate and the aspect correction is applied outside of XIMAGE. Further modifications will include the conversion of the fortran code for unix, and some treatment of exposure masks appropriate to subsections of data.
XRONOS This timing package interfaces with XIMAGE. Current problem is treatment of the exposure mask to obtain the correct exposure in each bin.
XSPEC There will be two possibilities to create spectra in the right format for Xspec. One is using XIMAGE and extracting a spectral file directly for XSPEC (this is something that works already for IPC spectra), the second is to write an interface from the PROS output (in progress).
(all of this is assuming no further changes to SASS output files)
IDL:
The Interactive Data Language is an interactive software system designed to facilitate quick reduction, analysis and visualization of the scientific data. IDL offers some features not currently available through PROS or XANADU, such as FITS file readers to convert the ROSAT A3DTABLE binary FITS files (such as the calibration and history files) into STSDAS tables which it can then read. The general data analysis routines available through the IUE RDAF system are being updated to run with IDL version 2, the update to version 2 is expected to be completed within the next 2 months.
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