Archiving and Availability of EUVE Data

Volume 13, Number 4, December 1997
By Joseph King and Derck Massa

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 ultraviolet (UV) and X-ray bands. The EUVE science and data managements' effort has been focused at the Center for EUV Astrophysics (CEA) of the University of California, Berkeley (UCB), under the leadership of Dr. Roger Malina.

The EUVE spacecraft.

The first six months of the mission were dedicated to mapping the sky in a set of four extreme ultraviolet (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 scan pattern for obtaining an all-sky survey.

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 Digital Linear Tape (DLT): the "science archive" consisting of images and photon lists ("events") and the "telemetry archive" containing all the raw data.

In the framework of the emerging Space Science Data Service, 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 (STScI) 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 HEASARC and STScI through interfaces familiar to those entities' traditional X-ray and optical/UV user communities, respectively. The data will initially be held for network access only at HEASARC, with links from both STScI and NSSDC. Support of the IRAF-based EUVE software will be from STScI.

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 but not all of the science potential of the EUVE data are at the science-archive level.

NSSDC is responding to requests for observations from the science archive tapes to be written to CD-WO disks. It is expected that in the near future HEASARC will also have the ability to do so.

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Miranda Beall, beall@nssdca.gsfc.nasa.gov, (301) 286-0162
Raytheon STX, Code 633, NASA Goddard Space Flight Center
Greenbelt, MD 20771, U.S.A.

Erin D. Gardner, gardner@nssdca.gsfc.nasa.gov, (301) 286-0163
Raytheon STX, Code 633, NASA Goddard Space Flight Center
Greenbelt, MD 20771, U.S.A.



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Author:Miranda Beall
Curators: Erin Gardner and Miranda Beall
Responsible Official: Dr. Joseph H. King, Code 633
Last Revised: 26 JAN 98 [EDG]