Meredith Durbin — astronomer and resolved stellar populations researcher

Meredith Durbin is a researcher whose work spans resolved stellar photometry, distance-scale measurements, and instrument calibration for space-based observatories. She is best known for leading the PHATTER survey — a panchromatic census of 22 million stars in the inner roughly 0.1 square degrees of the Triangulum Galaxy (M33) using the Hubble Space Telescope — and for developing the MCR-TRGB method, a multivariate Gaussian approach to measuring the tip of the red giant branch that handles the color-dependence problems that standard one-dimensional edge-detection algorithms cannot resolve in the near-infrared. Her roles have spanned instrument calibration at the Space Telescope Science Institute, graduate research at the University of Washington, and, from 2023 onward, a postdoctoral position at the University of California, Berkeley.

Key facts

  • Occupation: researcher
  • Employer: Space Telescope Science Institute

Education and early training

Durbin began her post-secondary studies at Santa Rosa Junior College, earning an Associate of Science in Natural Sciences in 2010. She then transferred to Pomona College, where she completed a Bachelor of Arts in Physics in 2014. Her senior thesis, advised by Alma Zook, examined the mid-infrared period-luminosity relation for RR Lyrae variable stars — a class of pulsating giant stars used as distance indicators — and was titled “The Mid-Infrared RR Lyrae Period-Luminosity Relation.”

In 2018 she received a Master of Science in Astronomy from the University of Washington, where she continued as a Graduate Research Assistant until 2023. Her listed research fields at the University of Washington Department of Astronomy are galaxies, instrumentation, and stars.

Instrument work at STScI

From 2014 to 2016, before entering graduate school, Durbin worked at the Space Telescope Science Institute as a Research and Instrument Analyst. During that period she served as Principal Investigator of Hubble Space Telescope program 14374, the WFC3 IR Dark Monitor — a calibration program that tracks the dark-current behaviour of the Wide Field Camera 3 infrared detector. That hands-on calibration experience gave her a detailed understanding of the instrument characteristics she would later rely on when designing and interpreting large resolved-star photometry campaigns.

The Carnegie-Chicago Hubble Program

In 2016 Durbin appeared as a named author on the first paper of the Carnegie-Chicago Hubble Program, published in The Astrophysical Journal (volume 832, number 2) and led by Rachael L. Beaton and Wendy L. Freedman. The program’s stated aim was to reach a 3 percent measurement of the Hubble constant — the rate at which the universe is expanding — using Population II distance indicators, a class of old, metal-poor stars that includes RR Lyrae variables and the tip of the red giant branch.

MCR-TRGB: a multivariate approach to the red giant branch tip

The tip of the red giant branch (TRGB) marks the luminosity at which low-mass stars ignite helium in a degenerate flash at their cores. Because this luminosity is nearly constant across a wide range of stellar ages and compositions, it serves as a reliable distance indicator. Traditional measurements locate the tip by running a one-dimensional Sobel edge-detection filter along the luminosity function in a single photometric band. That approach degrades in the near-infrared, where the tip’s brightness varies with stellar colour and small systematic offsets in colour can shift the inferred distance.

Durbin led the development of the MCR-TRGB method, which fits an n-dimensional Gaussian to the photometry of candidate red giant branch tip stars across multiple bands simultaneously. Co-authors on the resulting paper include Rachael L. Beaton, Julianne J. Dalcanton, Benjamin F. Williams, and Martha L. Boyer. By treating colour and magnitude jointly rather than marginalising over colour, the method can separate the genuine tip from contaminating populations and propagate photometric uncertainties self-consistently — a property she later elaborated at a Kavli Institute for Cosmological Physics seminar at the University of Chicago, where she also described applying the extreme deconvolution algorithm (XDGMM) to account for colour-magnitude covariance.

PHATTER: mapping M33 star by star

Released on March 15, 2021, the Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER) is a High-Level Science Product built from Hubble Space Telescope imaging of the central roughly 0.1 square degrees of M33, the Triangulum Galaxy. Durbin and Benjamin F. Williams are listed as the two HLSP authors. The survey delivers ultraviolet, optical, and near-infrared photometry of 22 million individual stars through six HST filters spanning the range from F275W (near-ultraviolet) to F160W (near-infrared). The resulting catalogue supports studies of stellar populations, star formation histories, and dust across one of the nearest spiral galaxies. The survey paper was published in The Astrophysical Journal Supplement Series.

PHAST: the southern half of Andromeda

Durbin is a co-author on the Panchromatic Hubble Andromeda Southern Treasury (PHAST), released on January 16, 2025. PHAST is a 195-orbit Hubble Space Telescope survey covering approximately 0.45 square degrees of the southern half of M31’s star-forming disk at optical and near-ultraviolet wavelengths. Its first data paper reported ultraviolet and optical photometry for over 90 million stars in M31 — the Andromeda Galaxy, the largest member of the Local Group. At 195 orbits, PHAST ranks among the largest HST resolved stellar photometry campaigns ever directed at M31’s southern disk.

When combined with the earlier Panchromatic Hubble Andromeda Treasury (PHAT) survey of the northern disk, PHAST’s footprint spans roughly two-thirds of M31’s star-forming disk. That combined coverage enables the highest-resolution spatially resolved star formation histories achieved for any large spiral galaxy outside the Milky Way.

JWST early-release science

Durbin is also a co-author on paper VII of the JWST Resolved Stellar Populations Early Release Science Program. That paper empirically assessed the accuracy of exposure-time estimates produced by version 3.0 of the JWST NIRCam Exposure Time Calculator, using actual observations of resolved stars in Local Group targets to compare predicted and measured signal-to-noise ratios. Instrument performance verification of this kind directly informs how future observing proposals are designed, because an over- or under-estimated exposure time propagates into missed science or wasted orbit time.

Current position

From 2023 onward Durbin has held a Postdoctoral Scholar position at the University of California, Berkeley, where she continues research in resolved stellar populations and related instrumentation topics.

Did you know

  • The PHAST survey Durbin contributed to catalogued over 90 million stars in M31 across 195 Hubble Space Telescope orbits, making it one of the largest HST resolved stellar photometry campaigns ever undertaken in M31’s southern disk. (archive.stsci.edu)
  • The MCR-TRGB method she led fits an n-dimensional Gaussian to photometry of candidate red giant branch tip stars simultaneously across multiple bands — an approach that overcomes colour-dependence issues that traditional one-dimensional edge-detection methods cannot handle in the near-infrared. (arxiv.org)
  • Before beginning her PhD, Durbin spent two years (2014–2016) as an instrument calibration specialist at the Space Telescope Science Institute, directly operating Hubble’s WFC3 detector monitoring programs. (meredith-durbin.github.io)
  • When combined with the earlier PHAT northern survey, PHAST’s coverage spans roughly two-thirds of M31’s star-forming disk, enabling the highest-resolution spatially resolved star formation histories of any large spiral galaxy outside the Milky Way. (arxiv.org)
  • Durbin delivered a Kavli Institute for Cosmological Physics (KICP) seminar at the University of Chicago titled “Nailing the Near-IR Tip of the Red Giant Branch with HST: Status, Prospects, and Challenges,” in which she described using the extreme deconvolution algorithm (XDGMM) for self-consistent multiwavelength TRGB measurements that account for photometric uncertainties and colour-magnitude covariance. (astrophysics.uchicago.edu)

Data sources

Where it appears

Data updated: 2026-10-31