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GALEXLOG - Galaxy Evolution Explorer (GALEX) Observation Log



This table contains the Galaxy Evolution Explorer (GALEX) observation log of the extant and planned observations to be made by this satellite observatory. The Galaxy Evolution Explorer (GALEX) is a NASA Small Explorer Mission launched on April 28, 2003. GALEX has been performing the first Space Ultraviolet sky survey. Five imaging surveys in each of two bands (FUV: 1350-1750 Angstroms and NUV: 1750-2800 Angstroms) range from an all-sky survey (limiting mAB ~ 20 - 21) to an ultra-deep survey of 4 square degrees (limiting mAB ~ 26). Three spectroscopic grism surveys (spectral resolution R = 100 - 300) are underway with various depths (mAB ~ 20 - 25) and sky coverage (100 to 2 square degrees) over the 1350 - 2800 Angstroms spectral range. The instrument includes a 50-cm modified Ritchey-Chretien telescope, a dichroic beam splitter and astigmatism corrector, two large, sealed-tube microchannel plate detectors to simultaneously cover the two bands and the 1.2-degree field of view. A rotating wheel provides either imaging or grism spectroscopy with transmitting optics.

The GALEX mission also includes an Associate Investigator program for additional observations and supporting data analysis which supports a wide variety of investigations made possible by the first UV sky survey.

The HEASARC provides this table of GALEX observations as an assistance to the high-energy astrophysics community, e.g., to enable cross-correlations of GALEX with X-ray observations. The GALEX data are available via MAST at More information about GALEX can be found at and


The GALEXLOG database table was last updated on 29 May 2011.


GALEX Archive Search Tool at Caltech:


This table was first created in July 2010 using the input file obtained from the Caltech GALEX site. This table is updated within a week of the update of the original file.


The observation designation. Note that because GALEX is a survey mission only targets listed as part of the GI program (names beginning with 'GI') are guaranteed to be observed with at least the listed 'Planned Exposure Time'.

The sub-visit number.

The Right Ascension of the pointing in the selected equinox. This was given in J2000.0 decimal degrees in the original table.

The Declination of the pointing in the selected equinox. This was given in J2000.0 decimal degrees in the original table

The Galactic Longitude of the pointing direction.

The Galactic Latitude of the pointing direction.

This parameter flag indicates the GALEX observation type:

    g = Grism
    i = Imaging
    u = Unknown

A code indicating the type of GALEX survey under which the observation was carried out (the sensitivities of the asterisked types are discussed in, as follows:

    AIS - All Sky Survey*
    CAI - Calibration Imaging
    CAS - Calibration Spectroscopy
    DIS - Deep Imaging Survey*
    DSS - Deep Spectroscopic Survey*
    ETI - Exceptional Imaging Survey
    ETS - Exceptional Spectroscopic Survey
    GII - Guest Investigator Imaging
    GIS - Guest Investigator Spectroscopy
    MIS - Medium Imaging Survey*
    MSS - Medium Spectroscopic Survey*
    NGS - Nearby Galaxy Survey*
    UDIS- Ultra-Deep Imaging Survey*
    WSS - Wide Spectroscopic Survey*

The number of separate exposures with the FUV detector that comprise the total FUV exposure time.

The number of separate exposures with the NUV detector that comprise the total NUV exposure time.

The planned exposure time, in seconds (s). This parameter can be used to determine if further observations are planned. If the column has 0 (for 'completed') or is less then the 'Total Exposure Time' then no further observations are planned. If the value is non-zero and greater then the 'Total Exposure Time' then further observations are likely to be scheduled to achieve the 'Planned Exposure Time'. If the value is negative, then the observation resulted in an overcountrate shutdown of the FUV and/or NUV detector, and no further observations will be made.

The total FUV detector exposure achieved, in seconds (s).

The total NUV detector exposure achieved, in seconds (s).

The available GALEX Data Release 4/5 (GR4/GR5) FUV archival exposure, in seconds (s).

The available GALEX Data Release 4/5 (GR4/GR5) NUV archival exposure, in seconds (s).

Contact Person

Questions regarding the GALEXLOG database table can be addressed to the HEASARC Help Desk.
Page Author: Browse Software Development Team
Last Modified: Wednesday, 09-Feb-2022 20:19:08 EST