Welcome to the MAST access site for browsing and retrieving GALEX data. The Galaxy Evolution Explorer (GALEX) is a NASA mission led by the California Institute of Technology aimed at investigating how star formation in galaxies evolved from the early Universe up to the present. GALEX will use microchannel plate detectors to obtain direct images in the near-UV (NUV) and far-UV (FUV) and a grism to disperse light for spectroscopy.

During its lifetime GALEX will also identify celestial objects for further study by ongoing and future missions. GALEX data will populate a large, unprecedented archive available to the entire astronomical community and to the general public via the MultiMission Archive at Space Telescope Science Institute (MAST). Pipeline processed GALEX data is periodically sent to MAST and ingested into its database, which can be accessed directly over the web in real time, or in the case of large volume requests by secure ftp.

GALEX was successfully launched on April 28, 2003. GALEX data products include a series of all sky surveys and deep sky surveys in the imaging mode and partial surveys in the near and far UV spectroscopic modes. Although originally planned as a 29-month mission, the NASA Senior Review Panel in 2004 recommended that the mission lifetime be extended.

During the course of the mission, the Project is releasing data to the public through MAST at discrete times; these are known as "Galex Releases." An initial sample of data, the ERO (Early Release Observations), was released by MAST in February, 2004. The first general GR release, GR1, was released during the winter of 2004/2005 in subsets separated by GALEX survey program type. The Project plans the release of GR2 in April/May, 2006. GR2 will again be broken up into subreleases with the first one covering the AIS (All Imaging Sky Survey). Subsequent public releases for the MIS, DIS, and NGS (respectively: Medium Imaging Survey, Deep Imaging Survey, Near Galaxies Survey) and spectroscopic (grism) data surveys are planned for later in the mission. A reprocessing of all products, including GI products (see below) is planned at the close of the mission (TBD).

The Guest Investigator (GI) program complements the general mission objectives. Cycle 3 of the GI program may be announced in spring of 2006. All GI products are proprietary for six months following archiving. At this writing some of the initially proprietary programs have been made public. Note that the GI data is accessed from a separate area on our website. However, because the project is obligated to give the GI all data products, regardless of the outcome of quality control tests, their quality is not necessarily the same as the public release data. Because of this issue, the GI data products cannot be searched on individual target names.

GALEX will use microchannel plate detectors to obtain direct images in the near-UV (NUV) and far-UV (FUV) and a grism to disperse light for spectroscopy. With its UV surveying capabilities, GALEX will complement the functions of the Hubble Space Telescope (HST) and the Far Ultraviolet Spectroscopic Explorer (FUSE), GALEX also complements the ground-based, optical Sloan Digital Sky Survey (SDSS) at optical wavelengths, which will ultimately cover 1/4 of the sky. Users can familiarize themselves with GALEX data products by selecting, browsing, and downloading them. A high-level description of data retrieval modes is provided on the Getting Started page. Help in navigating the website is provided by the GALEX/MAST tutorial.