About this Article
MAST Staff - 2026 Aug 28gPhoton Service Discontinuing
gPhoton is an open-source Python package that provides calibrated photon events from the GALEX mission to construct images, image time series, and light curves on demand. The package relies on a large database of pre-computed, calibrated photon events housed at STScI/MAST. Since gPhoton released in 2016, a newer service called gPhoton2 has superseded the capabilities and quality of gPhoton. Thus, MAST will be discontinuing support of gPhoton and tearing down the pre-computed, calibrated photon event list on December 7th 2026. At that time, the gPhoton package will largely be unusable.
The gPhoton package has not been actively maintained for some time now. gPhoton2 is superior: it runs 10 to 1000 times faster and has several improvements in the calibration quality. Furthermore, gPhoton2 does not rely on a pre-computed database of calibrated photon events that MAST needs to maintain. For any active researchers using gPhoton, we strongly encourage you to switch to gPhoton2 at your earliest convenience, in case you need to run some gPhoton queries for comparison purposes while the service is still available. For those starting new projects, you should exclusively use the gPhoton2 package.