PHAT: Hubble Space Telescope Survey of 100+ Million Stars in Andromeda Galaxy

The Panchromatic Hubble Andromeda Treasury (PHAT) dataset maps roughly one-third of the star-forming disk of the Andromeda Galaxy (M31). It was created by the Hubble Space Telescope using 6 ultraviolet, optical, and near-infrared filters, resolving the region into more than 100 million individual stars. The data is organized by the National Aeronautics and Space Administration (NASA) and was last updated in March 2026.

Use Cases

• Analyze stellar populations and star formation history based on multi-wavelength photometry across 6 filters.
• Study galaxy structure and metallicity gradients based on resolved star maps across a third of M31's disk.
• Model stellar evolution and luminosity functions based on photometric depth reaching ~28 magnitudes in uncrowded regions.
• Investigate the effects of crowding on photometric measurements based on depth variations with galactic radius.

Strengths

• Observations use the high resolution and sensitivity of the Hubble Space Telescope.
• Data covers 6 filters from ultraviolet (F275W, F336W) through optical (F475W, F814W) to near-infrared (F110W, F160W).
• Photometric depth reaches approximately 28 magnitudes in F475W in uncrowded outer disk regions.
• The survey is structured into 23 bricks for systematic, complete coverage of the target area.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Photometric depth is crowding-limited and varies significantly with galactic radius, being shallower in the inner bulge.
• Row count is unknown, which may limit suitability assessment for specific analysis scales.

Provenance

Source

National Aeronautics and Space Administration (NASA)

Collection Method

Observations from the Hubble Space Telescope's WFC3 and ACS cameras, organized into 23 bricks of pointings.

Time Range

Observations were taken in two seasons approximately six months apart.

Freshness

Last updated 2026-03-13 19:40:12.082206; freshness should be verified.

Geography

Covers roughly one-third of the star-forming disk of the Andromeda Galaxy (M31).