ROSAT Guest Observer Facility
ROSAT Browse Databases, by Patricia Tyler

The following ROSAT databases are available under Browse:

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  Name		Description		            Observatory  Updated 
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  ROSAO		Proposals 				ROSAT 	 95.201 
  ROSSTL	Short-term Timeline  			ROSAT 	 95.305 
  ROSLTL	ROSAT Long Term Timeline		ROSAT 	 96.081
  ROSATLOG 	Observation Log 			ROSAT 	 96.037 
  ROSOBS	Processing Status			ROSAT	 95.338 
  ROSDISTRIB 	Distributed Data 			ROSAT	 95.305 
  ROSPUBLIC	Archival Data 				ROSAT 	 96.034 
  ROSID		SIMBAD for ROSAT Databases		ROSAT 	 95.129 
  WFCBSC	Catalog of WFC Bright Sources		ROSAT 	 95.082 
  WFCPOINT	WFC Public Archive			ROSAT 	 95.082 
  ROSATSRC	Catalog of Rev0/1 PSPC sources		ROSAT	 95.082 
  WGACAT	Catalog of PSPC WGA Srcs Rev 1		ROSAT 	 95.134 
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ROSAO - Proposals

The ROSAO database contains a complete list of all accepted ROSAT AO proposals. The total observation time amounts to 180% of that available, with a 1st, 2nd, 3rd priority system used to establish the probability of an observation taking place. All priority 1 and 2 observations will be eventually be made. The priority 3 observations are used to fill gaps in the observing program and not all will be performed.

ROSSTL - ROSAT Short-term Timeline

The ROSSTL database is based on the ROSAT short term timeline. This is generated by MPE approximately one week in advance of observations, and is incorporated into the database (via the UKDC) accordingly. It contains details of all scheduled pointed observations on a one entry per slot basis, where a "slot" is an observation interval (OBI) of constant celestial pointing with detector HTs switched on.

ROSLTL - ROSAT Long-Term Timeline

The ROSLTL database is currently based on the first half of ROSAT AO-6, covering the period October 1995 to March 1996 but shoud be updated through the second half of AO-6 (April - October 1996) by the distribution of this newsletter.

Note that accurate ROSAT orbit prediction many months ahead is not possible, thus individual slot times at the ends of the two timelines may be substantially revised in the short term times lines produced a week or so before the observations.

The ROSLTL database has been made from a file provided by the UKDC. It contains details of all scheduled pointed observations on a one entry per slot basis, where a "slot" is an interval of constant celestial pointing with detector switched on.

ROSATLOG - ROSAT Log of Observations

ROSATLOG is made by cross-correlating ROSAT observation records with the short-term timeline and contains information about all pointings executed by the satellite during the performance verification (PV) and AO phases. For each observation, details are given concerning target name and coordinates, pointing start and stop times, PI name and country, ROSAT Observation Request sequence number, and more.

ROSATLOG is periodically updated as new short-term timelines and observation records are generated at the German ROSAT Science Data Center at the Max PlanckInstitute for Extraterrestrial Physics (MPE) and sent to the ROSAT Guest Observer Facility at Goddard Space Flight Center (GSFC).

The ROSATLOG database has been made as accurate a record of ROSAT pointings as is possible with the available information. The primary source of information for the database is ASCII files dumped from a database at MPE. These ASCII files contain information originally extracted from the attitude protocol files, which are daily-generated files containing coordinate and time values for each day's ROSAT pointing. Errors in the information extracted from the attitude protocol files are weeded out and corrected in the database at MPE as necessary, and the final versions of the ASCII files are output and sent to the ROSAT GOF at GSFC, to be used as the basis for the ROSATLOG database.

Each observation listed in the MPE ASCII files has a ROSAT Observation Request (ROR) sequence number associated with it. Using this sequence number, the observation is matched with the corresponding entry in the ROSAT short-term timeline. (The short-term timeline is also generated by MPE, approximately one week in advance of observations. It is available online within the HEASARC database system, as a database called ROSSTL.) Information such as PI name, country, target name and number, primary instrument, solar angle, time constraints, etc., is then extracted from the timeline and put into the ROSATLOG database. (NOTE: Typing the BROWSE command "lparm" will display all the ROSATLOG parameter names and one-line descriptions to the screen. Those parameters with an asterisk at the beginning of their descriptions are parameters whose values come from the ROSAT short-term timeline; parameters without asterisks contain values extracted from the MPE ASCII files.)

Certain ROSATLOG entries may have parameter fields which contain "??", "UNKNOWN", or are blank. In these cases, either the ROR was not found in the short-term timeline or the ROR was found but the completed observation could not be matched with one of the planned observations listed in the short-term timeline.

Despite efforts to make ROSATLOG a complete and accurate record of ROSAT pointings, some errors may still appear; thus ROSATLOG should be used only as a basic guide to what pointings have been executed. ROSATLOG shows in which direction ROSAT pointed and at what time. HOWEVER, it does NOT reflect problems which may have occurred during the pointing and which can result in the total exposure time being much less than the duration of the pointing.

ROSOBS - ROSAT Observation Status

The ROSOBS database summarizes ROSAT pointed observations performed and/or scheduled in the AO-1 through AO-6 mission phases.

ROSDISTRIB - ROSAT Public Archive List

The ROSDISTRIB database contains the list of US and German ROSAT observations for which REV0 data have been distributed to the PI, including those data sets which have become available to the public. The ROSDISTRIB database is updated weekly, as new datasets are distributed to PI's and others are released for public use.

For each observation listed in ROSDISTRIB, the instrument used, processing site, and target name and coordinates are given, as well as the ROSAT observation request number (ROR), actual and requested exposure times, date the observation took place, date data were distributed to the PI, date data will become public, and more.

ROSPUBLIC - ROSAT Public Archive List

The ROSPUBLIC database contains the list of US and German ROSAT observations for which REV0 data have been distributed to the PI, including those data sets which have become available to the public. The ROSPUBLIC database is updated weekly, as new datasets are distributed to PI's and others are released for public use.

For each observation listed in ROSPUBLIC, the instrument used, processing site, and target name and coordinates are given, as well as the ROSAT observation request number (ROR), actual and requested exposure times, date the observation took place, date data were distributed to the PI, date data will become public, and more.

ROSID - ROSAT SIMBAD Identifications

The ROSID database is a byproduct of the ROSAT project. ROSID is a catalog of astronomical objects created from the SIMBAD database. It is used by the ROSAT project to generate the source lists which accompany processed ROSAT observations.

Each ROSID entry contains a source name and coordinates along with other information about the source. An earlier version of the ROSID database was restricted to a subset of the present database which coincided with a ROSAT pointing. The current version is the full database. Thus, although an object appears in the ROSID catalog, it does not imply that the object was either detected by or in the field of view of ROSAT.

WFCBSC - ROSAT Wide Field Camera Bright Source Catalogue

The WFCBSC database contains the ROSAT Wide Field Camera Bright Source Catalogue. It contains 384 bright EUV sources found during the ROSAT all sky survey of July 1990 to January 1991. The information in this pre-publication database is based on what will be published by Pounds et al . in MNRAS.

The British Wide Field Camera on the German/US/UK ROSAT spacecraft consists of a 5 degree diameter field of view EUV telescope with a curved microchannel plate detector with a resistive readout at the focus. It is sensitive in the range 60 to 200 Angstroms (60 to 200 eV). The WFC is coaligned with the larger German X-ray Telescope.

ROSAT performed a 6-month all-sky survey in the interval July 30, 1990 to January 25, 1991, during which 96 percent of the sky was covered. During the survey two filters were alternated daily to provide two EUV passbands. These were S1 [60-140 A (90-206 eV)] and S2 [110-200 A (62-110 eV)]. Sky coverage was greatest at the ecliptic poles, where integrated exposures reached 70,000 seconds in each filter; at the ecliptic equator exposures were lowest, being around 1,500 seconds per filter.

The sources listed in this Bright Source Catalogue were initially detected using a circular sliding box technique and a Poisson significance test. A maximum likelihood technique was used to determine source parameters. The criteria for inclusion of an EUV source in this catalogue were: greater than 4.5 sigma detection in one filter, and visual confirmation of the source. Simulations suggests that less than one false detection can be expected in the WFC Bright Source Catalogue.

WFCPOINT - ROSAT WFC Observations

The WFCPOINT database contains the current list of ROSAT-Wide Field Camera CAL, PV, and AO phase observations.

For each observation listed in WFCPOINT, the target name, celestial co-ordinates, sequence number, PI name, and proposal title are given. The date of the observation, date that the data were distributed, and the date that the data will be released to the public are also given. The public release date is nominally 1 year and 14 days after the distribution date; however, because of some processing problems with a few datasets, the actual release date will be delayed from the given date. The public flag indicates whether or not a dataset is currently available for public release.

For a more complete description of the ROSAT spacecraft and its instruments -- the WFC and the XRT-PSPC and XRT-HRI -- see the ROSAT AO users guide.

ROSATSRC - ROSAT PSPC source catalog from REV0/1 public pointings

This catalog contains ROSAT point sources detected by the standard analysis system SASS. The catalog is based on the public PSPC observations.

During the ROSAT workshop at MPE on October 26, 1994 Wolfgang Voges announced on behalf of the ROSAT Consortium (MPE-Garching, GSFC/SAO-US, and WFC-Consortium-UK) the public release of "The First ROSAT Source Catalogue of Pointed Observations with the PSPC". This catalogue contains 50,408 sources from 2876 pointed observations. For each source the following properties are provided: the observation number, the ROSAT name, the position in equatorial and in galactic co-ordinates, four positional errors (intrinsic, systematic, boresight, and total), the source count-rate and its error, the background countrate, exposure time, hardness-ratios HR1 and HR2 and their errors, extent and likelihood of extent, likelihoods of the map-detect algorithm and of the maximum-likelihood detection algorithm, flags to indicate in which energy band and by what algorithm the source was detected, the detection cell size, the off-axis radius, the distances to the nearest rib and source (before and after removal of ambiguous sources), and a source confusion flag (set if another source is within 2.1*FWHM of the point-spread function).

This catalogue contains observations which have been performed until the end of May 1993 and which are in the public archive. A visual inspection of all soft and hard images, and an automated screening process on the original so called master source lists (MASOL), have been used to remove confused sources and 124 observations with too crowded regions and regions of high surface brightness diffuse emission. The resulting 50,408 sources have a likelihood of at least 10, corresponding to a rate of accidental detections of about 1 percent. This data base contains 80% of all PSPC observations. Since the acceptance criteria were rather conservative a total number of about 70,000 X-ray sources detected during the pointed PSPC observation phase can be expected.

WGACAT - Catalog of PSPC WGA Sources (1st rev)

This is the 1st revision of the WGACAT point source catalogue. It was generated from all ROSAT PSPC pointing observations from Feb 1991 to March 1994 which were available in the public archive at HEASARC in Feb 1995. This catalog has been generated by N.E. White (HEASARC/GSFC),

P. Giommi (ESIS/ESA), and L. Angelini (HEASARC/GSFC) and is a private research effort not related to the official catalog planned by the ROSAT project. The total number of unique sequences (ROR) that were processed is 3007 and includes both the US and the German/UK public archived data. The catalog currently contains in excess of 68,000 detections, with more than 62,000 individual sources.

The current version of WGACAT was released in March 1995. The original version was released in November 1994. The 1st revision contains the following changes:

  • An offset in the positions has been corrected.

  • The addition of another ~800 fields to give a total of 3007 unique RORs (compared to 2229 in the current version of ROSATSRC). Rev 1 has a total of ~68,000 detections and ~62,000 unique sources within 20 arc seconds radius of each other (compared to 49721 entries and 44542 unique sources in rev 0).

  • The removal of the overlap region between the inner and outer regions, by removing sources in the outer region at a radius less then 21 arc min. In this region edge effects combined with the presence of the inner rib caused a spurious peak in the number of detected sources.

  • The source designations have been revised to be prefixed by 1WGA to distinguish them from sources designated in rev 0.

  • A lightcurve and spectrum has been accumulated for each source. These are provided as products available through the HEASARC browse interface for download or display. The lightcurve and spectrum are given in gif format for instant display, and also as an event file and a pha spectrum in FITS format for further analysis. The background is provided accumulated over the whole field with the detected sources removed. These are intended as quick look products, and should be used with care.

  • The lower channel used for the soft band has been changed from zero to 12. Two additional ratios (HR SOFT and HR HARD) are provided in the range covered by the original hardness ratio, to give more sensitivity to spectral changes.

  • Errors in the calculation of the AOX and AOR parameters have been corrected.

  • Additional catalogs have added to the cross-correlation and the order of these correlations changed to give the best results.

  • A cross correlation against ROSATSRC has been made and the results written to the WGACAT database.

    There is a WGACAT page on the World-Wide-Web which has the latest information and links to publications about WGACAT. The link is http://heasarc.gsfc.nasa.gov/~white/wgacat/wgacat.html.


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    This file was last modified on Tuesday, 17-Jul-2001 12:02:02 EDT

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