Data from the X-ray Observatory ROSAT

H.U. Zimmermann, H. Brunner, R. Pisarski, W. Voges & M.G. Watson

ROSAT Services

ROSAT Centres in Germany, the UK and the USA (at MPE and GSFC for the XRT, at Leicester and AIT for the WFC) offer on-line services, through which users can access ROSAT related information like status reports, timelines, observation lists, software, etc. and retrieve data from the ROSAT Archives.

The following sections give short descriptions of the contents and the access to the services at the time of writing. Please consider that some access possibilities and services may have already changed from the examples given here. Every installation provides on-line help reflecting the actual status.


On-Line Services at the German RSDC

Mail address
ROSAT Scientific Data Center Max-Planck-Institut fuer Extraterrestrische Physik Postfach 1603 85740 Garching Germany
rosat_svc@mpe-garching.mpg.de
Fax: +49 89 3299-3569

ROSAT Service Area or via ftp access
BROWSE (rlogin access)

Information Services

The German data centre at MPE provides electronic services through the so-called ROSAT Service Area (rosat_svc), accessible via anonymous ftp and World Wide Web services. Entering the Service Area the user finds information and data stored in a tree like directory structure. Each directory contains a file 'contents.doc' listing the available information. The files 'help.doc' and 'updates' in the top level directory provide help and list the names of new or updated files. Information is grouped into the following main directory branches:
archive
archive info, utilities, entry to ROSAT Data Archive
calibration
instrument calibration related info and data
doc
ROSAT project and utility documents
exsas
EXSAS software, updates, bug lists
processing
status, shipping lists, bug lists
general
general items like status, publications, news
timeline
mission timelines, observation logs

ROSAT Data Archive (RDA)

The ROSAT Data Archive lies in the subdirectory 'data' of directory 'archive'. The data are stored in compressed form (using the public domain utility gzip) and therefore, after network transfer, have to be decompressed at the users site (subdirectory archive/tools contains help info and gzip code for UNIX and VMS systems).

Data from a specific observation, identified by its sequence number (6 digits) and an additional identifier ('p' for PSPC, 'f' for PSPC with filter and 'h' for HRI data), are stored in a subdirectory of directory 'archive/data'. PSPC data with sequence number 123456, for example, are stored in directory 'archive/data/123456p'. Follow up observation(s) have a postfix of '-1', '-2', ... E.g., the data of the first follow up observation of the above example are in archive/data/123456p-1.

Example session (copy data of PSPC observation 200014p):

% ftp rosat_svc.mpe-garching.mpg.de   connect to the Service Area
                         user: anonymous; password: e-mail address
ftp> cd archive/data    go to RDA main directory 
ftp> cd 200014p         proceed to proper observation directory
ftp> bin                set binary mode transfer
ftp> prompt             avoid prompting using mget
ftp> mget *             copy all files from the directory
ftp> bye                leave ftp
% gzip -d *-gz          decompress files
Now the data (in FITS format) are ready for input to one of the interactive analysis systems (EXSAS, PROS). To receive data on tape (cassette), archive requests may also be sent via mail or e-mail to the RSDC. The proper request form is available in directory 'archive'.

Interactive Access (BROWSE)

ROSAT mission logs, timelines, data files, astronomical catalogues, towards the end of 1994 also the ROSAT Result Archive, can be interactively accessed (see above) via the BROWSE utility (at MPE the version provided by GSFC is installed).


On-Line Services at GSFC

Mail address
ROSAT Science Data Center, GSFC/NASA, Code 631, Green Belt, Maryland 20771, U.S.A.
request@ndadsa.span (HEASARC)

ROSAT Guest Observer Facility
US ROSAT Data Center
GSFC provides ROSAT Services maintained by the US RSDC, the HEASARC (High Energy Astrophysics Science Archive Research Center), and the OGIP (Office for Guest Investigator Programs) groups.

HEASARC Services

By logging in to the HEASARC on-line services, users can access ROSAT status reports, timelines, the AO proposal list, and an observation log. The captive account XRAY may be accessed via SPAN or telnet.

ROSAT information is available within the XRAY account through the bulletin board and the database system. To access the bulletin board, simply type 'BULLETIN'; information on the latest HEASARC developments is posted there, as are status reports for ROSAT and GRO.

To access the database system, type 'BROWSE' followed by the name of the database you wish to view. ('BROWSE ?' lists available databases.) BROWSE is a command-driven program which allows users to manipulate, display, and execute analysis tasks on database entries.

Example session (search ROSATLOG for a specific PI name):

HEASARC> BROWSE ROSATLOG    load the ROSATLOG database
...> HELP                   get help on browse commands
...> DBHELP                 get help on current database
...> SP PI WHITE            Search the total sample for entries 
                            with 'WHITE' as PI. All entries 
                            will be displayed.  
...> DALL 1                 display all information in entry 1
...> RSAM                   reset the sample to TOTAL again
...> EXIT                   quit browse
ROSAT public archive data can be extracted using the BROWSE request command.
Example session (obtaining data from the US public archive once data 
files are located):

HEASARC> BROWSE ROSUSPSPC   load the US PSPC database
...> SC                     do coordinate search (prompts for values)
...>                        displays all files matching search criterion
...> REQUEST                starts automatic procedure to de-archive the data
                            that user requested as file numbers. Will prompt
                            user for their e-mail address
...> EXIT
BROWSE will send a request for data to ARMS (Automated Retrieval Mail System). ARMS will de-archive and place the data in an anonymous FTP area that the user can access for downloading. The system will also notify the user via e-mail when the de-archiving has been completed. For more information see the document 'Using the US Public Data Archive' (see below).

BROWSE can also be accessed via the www HEASARC home page as given in the header.

The ROSAT Anonymous FTP Account

The Office for Guest Investigator Programs (OGIP) has a multi-mission anonymous ftp account. At the top level the user sees the directory trees for all OGIP missions and some general directories. The ROSAT directory contains information on problems, timelines, data, etc. ROSAT related calibration information can also be found in the caldb area.

A subset of ROSAT archival data that was used for instrument calibration can be found under the directory
rosat/data/<hri or pspc>/processed_data/<seq-id group>/<seq-id>,
where <seq-id group> is one of 100000, 200000, ... 900000. For example, data associated with the data set having sequence id rp300023 is located in the directory
rosat/data/pspc/processed/data/300000/rp300023.

To minimize storage space, the data are stored on the jukebox in UNIX compressed format. Users can uncompress the data automatically when ftp'ing. To do this, simply "get" the file by specifying the filename WITHOUT the .Z extension. An example is shown below:

% ftp legacy.gsfc.nasa.gov   user: anonymous; password: e-mail address 
ftp> cd rosat/data/pspc/processed_data/300000/rp300023
ftp> ls rp300023.fits.Z
rp300023.fits.Z
ftp> bin
ftp> get rp300023.fits
ftp> quit
This automatic uncompression will work for both VMS and UNIX systems. Users should note that automatic uncompression does NOT work with the ftp "mget" command. If the user wants to have access to the full archive then it is urged that as a first step the document Using the US ROSAT Public Data Archive should be obtained. The document describes in detail how to obtain data via BROWSE, ARMS or MIPS.

MIPS

The Mission Information and Planning System (MIPS) is an on-line information retrieval system (on a VAX computer, see address header) devised for ROSAT guest observers. MIPS contains software tools to:


On-Line Services at the Leicester Database and Archive Service (LEDAS)

Mail address
Leicester Database and Archive Service (LEDAS)
Department of Physics and Astronomy,
University of Leicester,
Leicester LE1 7RH,
United Kingdom
Fax: +44 533 550182

The LEDAS is located in the X-ray Astronomy Group in the Department of Physics, Leicester University, UK. The LEDAS incorporates on-line archive data from several X-ray astonomy missions; ROSAT-XRT and WFC AO programme, ROSAT-WFC Survey, Ginga, EXOSAT and Einstein. Well over 100 astronomical catalogues from radio to gamma-ray observations are also supported. The LEDAS databases can be accessed as follows:

1) telnet to ledas.star.le.ac.uk

The LEDAS has installed the BROWSE command-line database query utility (supplied by the HEASARC at GSFC) within a dedicated captive account. Users telnet to ledas.star.le.ac.uk and log-on as 'xray' (no password required). Extensive on-line help is available within the captive account.

2) WWW Services

The LEDAS WWW pages offer a variety of services. The LEDAS user guide is available, along with specific pages concerning the ROSAT AO programme, ROSAT-WFC Survey and Ginga archives. The LEDAS also has a web interface, 'ARNIE', to the catalogue collection. The 'ARNIE' interface provides a simple way to browse catalogues and display on-lines images or extract associated data products.

Queries about the LEDAS can be emailed to On-Line Services at the German XUV Data Center

Mail address
XUV Data Center, Astronomisches Institut Tuebingen, Germany
gxuvdc@ait.physik.uni-tuebingen.de
Fax: +49 7071 293458
The service is available on a VAX cluster at the Astronomisches Institut der Universitaet Tuebingen (AIT).

Information Services

The main directory contains a list of contents (file contents.list), a help file (readme.txt), a listing of all observations processed at the data centre (file observation.list) and information on detected XUV sources (file source.list).

Archived Data

For each (filter-) observation an image (IMA), a merged exposure map (MEX), and an instrument map (INS) can be found on the sub-directories
<n>00_ror
where <n> = [1, 2,... 9, a], depending on the first digit of the ROR number. All images are 512x512 MIDAS images (.bdf), which are converted to FITS and then compressed, using the standard UNIX compress utility. File names are of the form <ROR-nr>.<type><nn>_Z where <type> is either IMA, INS, or MEX and <nn> is the number of the filter observation, e.g. 200141.INS01_Z. Typical sizes of the compressed images are 25-75 kbytes.

UNIX users can apply their usual compress facility to decompress the data. After renaming the extension of the compressed dataset from _Z to .Z type: compress -d 200141.ima01. VMS users can copy the executable COMPRESS.VMS from XUV_ARCHIVE:[XUV]. Then, at your home computer, rename it to COMPRESS.EXE and to install it, type:
COMPRESS := $<disk>:[path]COMPRESS.EXE.
To decompress a dataset, type: COMPRESS -d 200141.IMA01.

For the future, it is intended to also keep the photon event files of all sources detected by the WFC (extraction radius TBD) in the on-line archive.

For all public data the complete set of files (including photon files, attitude file etc. in EXSAS compatible FITS format) is available on tape. The request should contain the ROR number of the observation, your postal address and the prefered transport medium (EXABYTE (default) or mag-tape).


Abstract from a chapter of Information & On-line data in Astronomy
Kluwer Academic Publishers, Daniel Egret & Miguel A. Albrecht (Editors)
Last update: Dec 16, 1995