gPhoton: THE GALEX PHOTON DATA ARCHIVE

Journal Article · Tue Dec 20 00:00:00 EST 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/833/2/292· OSTI ID:22661450

Million, Chase ^[1]; Fleming, Scott W.; Shiao, Bernie; Smith, Myron; Thompson, Randy; White, Richard L. ^[2]; Seibert, Mark ^[3]; Loyd, Parke ^[4]; Tucker, Michael ^[5]

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1. Million Concepts LLC, P.O. Box 119, 141 Mary Street, Lemont, PA 16851 (United States)
2. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
3. The Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
4. Laboratory for Atmospheric and Space Physics, Boulder, Colorado, 80309 (United States)
5. Dept. of Physics and Astronomy, Appalachian State University, Boone, NC 28608 (United States)

gPhoton is a new database product and software package that enables analysis of GALEX ultraviolet data at the photon level. The project’s stand-alone, pure-Python calibration pipeline reproduces the functionality of the original mission pipeline to reduce raw spacecraft data to lists of time-tagged, sky-projected photons, which are then hosted in a publicly available database by the Mikulski Archive at Space Telescope. This database contains approximately 130 terabytes of data describing approximately 1.1 trillion sky-projected events with a timestamp resolution of five milliseconds. A handful of Python and command-line modules serve as a front end to interact with the database and to generate calibrated light curves and images from the photon-level data at user-defined temporal and spatial scales. The gPhoton software and source code are in active development and publicly available under a permissive license. We describe the motivation, design, and implementation of the calibration pipeline, database, and tools, with emphasis on divergence from prior work, as well as challenges created by the large data volume. We summarize the astrometric and photometric performance of gPhoton relative to the original mission pipeline. For a brief example of short time-domain science capabilities enabled by gPhoton, we show new flares from the known M-dwarf flare star CR Draconis. The gPhoton software has permanent object identifiers with the ASCL (ascl:1603.004) and DOI (doi:10.17909/T9CC7G). This paper describes the software as of version v1.27.2.

• OSTI ID: 22661450
• Journal Information: Astrophysical Journal, Vol. 833, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
APPROXIMATIONS
CALIBRATION
CATALOGS
COMPUTER CODES
DATA ANALYSIS
DIAGRAMS
DWARF STARS
IMAGES
IMPLEMENTATION
PHOTONS
SKY
SPACE
SPACE VEHICLES
STELLAR FLARES
TELESCOPES
ULTRAVIOLET RADIATION
VISIBLE RADIATION