The Astrophysical Journal (Jan 2025)
PHAST. The Panchromatic Hubble Andromeda Southern Treasury. I. Ultraviolet and Optical Photometry of over 90 Million Stars in M31
- Zhuo Chen,
- Benjamin Williams,
- Dustin Lang,
- Andrew Dolphin,
- Meredith Durbin,
- Julianne J. Dalcanton,
- Adam Smercina,
- Léo Girardi,
- Claire E. Murray,
- Eric F. Bell,
- Martha L. Boyer,
- Richard D’Souza,
- Karoline Gilbert,
- Karl Gordon,
- Puragra Guhathakurta,
- Francois Hammer,
- L. Clifton Johnson,
- Tod R. Lauer,
- Margaret Lazzarini,
- Jeremiah W. Murphy,
- Ekta Patel,
- Amanda Quirk,
- Mariangelly Díaz Rodríguez,
- Julia Christine Roman-Duval,
- Robyn E. Sanderson,
- Anil Seth,
- Tobin M. Wainer,
- Daniel R. Weisz
Affiliations
- Zhuo Chen
- ORCiD
- Department of Astronomy, Box 351580, University of Washington , Seattle, WA 98195, USA ; [email protected]
- Benjamin Williams
- ORCiD
- Department of Astronomy, Box 351580, University of Washington , Seattle, WA 98195, USA ; [email protected]
- Dustin Lang
- ORCiD
- McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University , 5000 Forbes Ave., Pittsburgh, PA, USA
- Andrew Dolphin
- ORCiD
- Raytheon , Tucson, AZ 85756, USA; Steward Observatory, University of Arizona , Tucson, AZ 85726, USA
- Meredith Durbin
- ORCiD
- Department of Astronomy, Box 351580, University of Washington , Seattle, WA 98195, USA ; [email protected]; Department of Astronomy, University of California Berkeley , Berkeley, CA 94720, USA
- Julianne J. Dalcanton
- ORCiD
- Department of Astronomy, Box 351580, University of Washington , Seattle, WA 98195, USA ; [email protected]; Center for Computational Astrophysics, Flatiron Institute , 162 Fifth Ave., New York, NY 10010, USA
- Adam Smercina
- ORCiD
- Department of Astronomy, Box 351580, University of Washington , Seattle, WA 98195, USA ; [email protected]; Space Telescope Science Institute , 3700 San Martin Dr., Baltimore, MD 21218, USA
- Léo Girardi
- ORCiD
- Osservatorio Astronomico di Padova—INAF , Vicolo dell’Osservatorio 5, I-35122 Padova, Italy
- Claire E. Murray
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Dr., Baltimore, MD 21218, USA; The William H. Miller III Department of Physics & Astronomy, Bloomberg Center for Physics and Astronomy, Johns Hopkins University , 3400 N. Charles St., Baltimore, MD 21218, USA
- Eric F. Bell
- ORCiD
- Department of Astronomy, University of Michigan , 1085 S. University Ave., Ann Arbor, MI 48109-1107, USA
- Martha L. Boyer
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Dr., Baltimore, MD 21218, USA
- Richard D’Souza
- ORCiD
- Vatican Observatory , Specola Vaticana V-00120, Vatican City State
- Karoline Gilbert
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Dr., Baltimore, MD 21218, USA; The William H. Miller III Department of Physics & Astronomy, Bloomberg Center for Physics and Astronomy, Johns Hopkins University , 3400 N. Charles St., Baltimore, MD 21218, USA
- Karl Gordon
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Dr., Baltimore, MD 21218, USA
- Puragra Guhathakurta
- ORCiD
- Department of Astronomy and Astrophysics, University of California Santa Cruz , University of California Observatories, 1156 High St., Santa Cruz, CA 95064, USA
- Francois Hammer
- ORCiD
- GEPI, Observatoire de Paris , Paris Sciences et Lettres, CNRS, Place Jules Janssen, F-92195 Meudon, France
- L. Clifton Johnson
- ORCiD
- Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University , 1800 Sherman Ave., Evanston, IL 60201, USA
- Tod R. Lauer
- ORCiD
- NOAO , 950 North Cherry Ave., Tucson, AZ 85721, USA
- Margaret Lazzarini
- ORCiD
- Department of Physics and Astronomy, California State University , Los Angeles, CA 90032, USA
- Jeremiah W. Murphy
- ORCiD
- Department of Physics, Florida State University , 77 Chieftan Wy., Tallahassee, FL 32306, USA
- Ekta Patel
- ORCiD
- Department of Physics and Astronomy, University of Utah , 115 South 1400 East, Salt Lake City, UT 84112, USA
- Amanda Quirk
- ORCiD
- Department of Astronomy, Columbia University , 538 West 120th St., New York, NY 10027, USA
- Mariangelly Díaz Rodríguez
- ORCiD
- Department of Physics, Florida State University , 77 Chieftan Wy., Tallahassee, FL 32306, USA
- Julia Christine Roman-Duval
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Dr., Baltimore, MD 21218, USA
- Robyn E. Sanderson
- ORCiD
- Department of Physics & Astronomy, University of Pennsylvania , Philadelphia, PA 19104, USA
- Anil Seth
- ORCiD
- Department of Physics and Astronomy, University of Utah , 115 South 1400 East, Salt Lake City, UT 84112, USA
- Tobin M. Wainer
- ORCiD
- Department of Astronomy, Box 351580, University of Washington , Seattle, WA 98195, USA ; [email protected]
- Daniel R. Weisz
- ORCiD
- Department of Astronomy, University of California Berkeley , Berkeley, CA 94720, USA
- DOI
- https://doi.org/10.3847/1538-4357/ad7e2b
- Journal volume & issue
-
Vol. 979,
no. 1
p. 35
Abstract
The Panchromatic Hubble Andromeda Southern Treasury (PHAST) is a large 195-orbit Hubble Space Telescope program imaging ∼0.45 deg ^2 of the southern half of M31's star-forming disk at optical and near-ultraviolet (NUV) wavelengths. The PHAST survey area extends the northern coverage of the Panchromatic Hubble Andromeda Treasury (PHAT) down to the southern half of M31, covering out to a radius of ∼13 kpc along the southern major axis and in total ∼two-thirds of M31's star-forming disk. This new legacy imaging yields stellar photometry of over 90 million resolved stars using the Advanced Camera for Surveys in the optical (F475W and F814W), and the Wide Field Camera 3 (WFC3) in the NUV (F275W and F336W). The photometry is derived using all overlapping exposures across all bands, and achieves a 50% completeness-limited depth of F475W ∼ 27.7 in the lowest surface density regions of the outer disk and F475W ∼ 26.0 in the most crowded, high surface brightness regions near M31's bulge. We provide extensive analysis of the data quality, including artificial star tests to quantify completeness, photometric uncertainties, and flux biases, all of which vary due to the background source density and the number of overlapping exposures. We also present seamless population maps of the entire M31 disk, which show relatively well-mixed distributions for stellar populations older than 1–2 Gyr, and highly structured distributions for younger populations. The combined PHAST + PHAT photometry catalog of ∼0.2 billion stars is the largest ever produced for equidistant sources and is available for public download by the community.
Keywords
