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EUVE Archive Information

Date: Mon, 13 Apr 1998 15:50:01 -0400
Subject: EUVE Notice 

We apologize if you receive this notice more than once. In an attempt
to get this information out to the widest number of researchers as
possible we explode these messages to more than one of the
news lists used by the HEASARC, and this leads to some overlap in
email addresses

                        EUVE Archive

Since its launch in June, 1992, NASA's Extreme Ultraviolet Explorer (EUVE)
spacecraft has obtained sky survey and pointed spectroscopic observations
at 70-760 Angstroms, between traditional UV and X-ray bands.  The EUVE
science and data management effort has been focussed at the Center for EUV
Astrophysics of the University of California, Berkeley, under the
leadership of Dr. Roger Malina (http://www.cea.berkeley.edu/).

The first six months of the mission were dedicated to mapping the sky in a
set of four EUV bands using a set of telescopes mounted perpendicular to
the spacecraft spin axis.  At the same time, it also carried out a deep
survey of the ecliptic plane, using the main telescope which views the sky
along the spin axis.  Once the survey was complete, the mission entered a
Guest Observer phase, carrying out pointed spectroscopy observations.

The EUVE team had been providing public access to EUVE data from facilities
at UCB/CEA via network and via the production of CD-WO disks; such access
recently terminated owing to resource constraints.  As part of its
preparation for its future cessation, the UCB team has started providing
two data products to NSSDC on DLT tape: the "science archive" consisting of
images and photon lists ("events") and the "telemetry archive" containing
all the raw telemetry.

In the framework of the emerging Space Science Data Services
(http://ssds.nasa.gov), with its emphasis on "active archiving" at sites of
major science discipline expertise, NSSDC has been interacting with the
High Energy Astrophysics Science Archive Research Center (HEASARC) at
Goddard and with the Space Telescope Science Institute on optimal roles for
each in the management, dissemination, and user support for these EUVE
data.  These organizations have primary active archive responsibilities in
the X-ray and UV bands that bound the EUVE wavelength range.

The science archive data will be supported by both the HEASARC 
(http://heasarc.gsfc.nasa.gov/) and the STScI (http://archive.stsci.edu) through
interfaces familiar to those entities' traditional X-ray and optical/UV
user communities, respectively.  The data is available for immediate
network access via the HEASARC, with links from both STScI and NSSDC.
The primary mode of EUVE data dissemination support provided by CEA was
through the creation and mailing of CD-Recordable disks.  Some EUVE
data users may have a continuing preference for this mode of data access,
NSSDC will respond to requests for observations from the science archive
to be written to CD disks.

The HEASARC EUVE activities are described on the web pages at
http://euve.gsfc.nasa.gov. The HEASARC EUVE archive contains proprietary
and non-proprietary observations from the EUVE guest observer program
through the end of 1997.  The data in the EUVE archive will be supplemented
periodically with additional observations from the Center for Extreme
Ultraviolet Astronomy (CEA) as they are processed.  The contents comprise a
total of 26 GB of compressed data on 244 distinct targets (including
calibrations). Data are online for immediate download and may currently be
retrieved though anonymous FTP or the Web at
referenced by different servers. Proprietary data is also stored on-line
but is not readable by the public (or most HEASARC personnel). The HEASARC
is developing an EUVE observation log which will be available through its
W3Browse and other interfaces before the end of April 1998.  Users will be
able to select observation by name, time and position and retrieve
appropriate information.

Access to EUVE data at STScI (http://archive.stsci.edu/euve) is available
through the same WWW interfaces used for the Hubble Data Archive. Links are
provided for users to search the EUVE catalog and retrieve the data, obtain
help, and get information about data analysis. Once the search is done, the
user is presented with a list of all datasets matching the query
parameters. These can be then retrieved via ftp from HEASARC by using the
two hyperlinks available in the "Data Files" column: EVT, which points to
the event file,  and IMG, which points to the image file.  Support of the
IRAF-based EUVE software will be from the STScI, after CEA  completes the
upgrade to IRAF V2.11.

NSSDC will provide a permanent archive of both the science archive data and
the telemetry data.  At present, the latter data are not well supported as
UCB/CEA software needed to access and process observation-specific data
from the telemetry tapes was highly specific to the CEA ADP environment,
and is no longer supported there or elsewhere.  Most of the science
potential of the EUVE data are at the science-archive level, and only under
extreme circumstances would it be necessary to access the telemetry archive.

Michael Gunter, Roger Malina (CEA)
Nick White, Tom McGlynn, Steve Drake (HEASARC)
Joe King, Derck Massa (NSSDC)
Bob Hanisch, Paolo Padovani (STScI)