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E U U V V E
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ELECTRONIC "FLASH" OF THE EUVE OBSERVATORY
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Vol 4, No. 8b 29 Aug 1994 ISSN 1065-3597
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**************************************************
* *
* *
* PUBLIC RELEASE OF THE EUVE SKY SURVEY DATA *
* *
* *
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by Brett A. Stroozas
EUVE Science Archive Manager
The Center for Extreme Ultraviolet Astrophysics (CEA) is pleased to
announce the public release of the sky survey data from NASA's Extreme
Ultraviolet Explorer (EUVE) satellite. EUVE was launched on 7 June 1992,
from Cape Canaveral, Florida, into a near-Earth (550 km) orbit. Following
seven weeks of in-orbit checkout, the survey phase of the mission was
carried out from 24 July 1992 until 21 January 1993 and included the
following:
* an all-sky survey conducted by the three "scanning" telescopes in four
band passes covering the entire extreme ultraviolet wavelength range
(60-740 A);
* a concurrent "deep survey" (more sensitive by a factor of ten) of a
2x180 degree swath along the ecliptic conducted by the deep survey
telescope in two band passes covering the 70-365 A range.
Periods of gap-fill (e.g., due to pointed calibration observations made
during the survey) were carried out during the first six months of the Guest
Observer (GO) program. The completed survey data sets cover approximately
97% of the sky with exposures ranging from a few hundred seconds at the
ecliptic equator to 20 kiloseconds at the poles.
Survey Science Data Products
----------------------------
The main science data products from the survey include source catalogs,
skymaps and "pigeonholes". Two catalogs of the survey results have been
published in the literature: "The Extreme Ultraviolet Explorer Bright Source
List" (Malina, et al. 1994); and "The First EUVE Source Catalog" (Bowyer,
et al. 1994). For the confirmed detected sources contained therein, these
catalogs furnish coordinates, approximate count-rates (to within ~50%), and
optical identifications (where available).
The survey sky maps are packaged as sets of binned raw photon (~1.3'
resolution) and exposure (~10' resolution) FITS maps for each survey band
pass.
An EUVE "pigeonhole" is a file which contains the time-tagged photon event
information within a small radius (typically 0.4 degrees) of a given location
on the sky. The pigeonhole files, which provide the maximum amount of available
information for each target location, are available in FITS bintable format.
Survey Data Accessible Via WWW URL
----------------------------------
Access to the EUVE science data products is now available via the CEA
World-Wide-Web (WWW) URL:
http://www.cea.berkeley.edu
(formerly http://ftp.cea.berkeley.edu). For those not having the relevant
software (e.g., NCSA's Mosaic), a text-based version is available locally at
CEA via telnet:
telnet www.cea.berkeley.edu 200
Three services -- the EUVE Count-Rate, the Skymap Request and the Pigeonhole
Request service -- have been implemented to provide researchers with access
to the EUVE survey data products. Due to the size and complexity of the data
products provided, as well as to the processing and delivery time involved, we
recommend that researchers access these products in the following manner:
1. SEARCH CATALOGS -- Researchers are first encouraged to search the published
catalogs for source(s) of interest. The full text and tables of the
survey catalogs (Malina, et al. 1994; Bowyer, et al. 1994), which
cover both the all-sky and deep surveys, are available on-line. A
tool to assist users in searching these catalogs will soon be available.
2. OBTAIN SOURCE COUNT-RATE INFORMATION -- Researchers may obtain source
count-rate information (e.g., for those sources not appearing in the
published catalogs) by using the EUVE Count-Rate service. This service
calculates count-rate information for *point* sources only by searching
and analyzing the skymaps for any significant source(s) near an input
location. Count-rate results are processed within hours and returned
via e-mail to the requester. This service currently provides access
to the all-sky survey skymaps only; those from the deep survey skymaps
will be available in the future.
3. OBTAIN SOURCE SKYMAP -- For those sources for which the EUVE Count-Rate
service indicates significant detections, the researcher is encouraged
to verify these results by obtaining and examining images of the source
by using the EUVE Skymap Request service. For a given input location
this service creates small raw photon (1.3' resolution) and exposure
(10' resolution) skymaps in FITS image format. When completed, the
requester is notified via e-mail that the skymaps are available for
pick-up in the CEA anonymous ftp site (www.cea.berkeley.edu). This
service currently provides access to the all-sky survey skymaps only;
the deep survey skymaps will be available in the future.
4. OBTAIN SOURCE PIGEONHOLE -- For detailed count-rate and timing analyses the
researcher will need the pigeonhole information which is accessible via
the EUVE Pigeonhole Request service. Given an input location, this
service will create a pigeonhole from the survey data in FITS Bintable
format. When completed (which may take up to five days), the requester
will be notified via e-mail that the pigeonhole is available for pick-up
in the CEA anonymous ftp site. Researchers should note that, although
pigeonholes contain the maximum amount of scientific information for a
given source, they are also the most complicated data products to
understand and use. Proper interpretation of pigeonhole data requires
the use of supplemental calibration data -- effective areas, point-
spread-functions and vignetting maps -- which are also available.
Detailed documentation is provided on-line for all of the above. Over the
coming months the EUVE Science Archive will continue to work on improving and
augmenting the available survey data, services and accompanying documentation.
Please help us to help you with your EUVE research by sending your questions,
comments and/or suggestions to archive@cea.berkeley.edu.
REFERENCES
==========
o Bowyer, S., Lieu, R., Lampton, M., Lewis, J., Wu, X., Drake, J.J., and
Malina, R.F., "The First EUVE Source Catalog", Astrophysical Journal
Supplement, 93(2), 1994 [CEA publication #565]
o Malina, R.F., et al., "The Extreme Ultraviolet Explorer Bright Source List"",
Astronomical Journal, 107(2), 751-764, 1994 [CEA publication #553]
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The EUVE Electronic Newsletter is issued by the Center for Extreme Ultraviolet
Astrophysics, University of California, Berkeley, CA 94720, USA. The opinions
expressed are those of the authors. EUVE Principal Investigators and Newsletter
Publishers: Drs. R.F. Malina and C.S. Bowyer. EGO and Archive Science Manger:
C.A. Christian. Archive Manager and Newsletter Editor: B.A. Stroozas. Funded
by NASA contracts NAS5-30180 and NAS5-29298. Send newsletter correspondence
to: ceanews@cea.berkeley.edu. The EUVE project is managed by NASA's GSFC.
The GSFC Project Manager: Paul Pashby, Project Scientist: Dr. Yoji Kondo,
Deputy Project Scientist: Dr. Ronald Oliversen. NASA HQ Program Scientist:
Dr. Robert Stachnik, Program Manager: Dr. G. Riegler. GSFC Project Operations
Director: Mr. Kevin Hartnett. Information on the EUVE Guest Observer Program
is available from: Dr. Y. Kondo, Mail Code 684, GSFC, Greenbelt, MD 20771 at
(301) 286-6247 or e-mail to euve@stars.span.nasa.gov.
END-----------EUVE------------ELECTRONIC---------------NEWS-------------END
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