The Panchromatic Hubble Andromeda Treasury


The Panchromatic Hubble Andromeda Treasury is a Hubble Space Telescope Multi-cycle program to map roughly a third of M31’s star forming disk, using 6 filters covering from the ultraviolet through the near infrared.  With HST’s resolution and sensitivity, the disk of M31 is resolved into more than 100 million stars, enabling a wide range of scientific endeavors.


Primary Science Goals

  1. 23 “bricks”, each consisting of an efficient 3x6 array of HST pointings

  2. 2 orbits per pointing.

  3. Filters: F275W+F336W (WFC3/UVIS), F475W+F814W (ACS/WFC), F110W+F160W (WFC3/IR)

  4. Detections of 117 million stars

  5. Survey description in Dalcanton et al 2012

  6. Description of latest photometry in Williams et al 2014

  7. Data products distributed through MAST here.

Key Survey Features

  1. Star formation histories derived on 50-100 parsec scales

  2. Improved stellar evolution models, calibrated at UV through NIR wavelengths

  3. Well-defined catalogs of stellar clusters, at all ages

  4. Characterization of variations in the stellar mass function from ~3 to 30 solar masses

  5. Measurements of the mass function and age distributions of stellar clusters

  6. Maps of extinction from dust, and characterization of the extinction law

  7. Calibration of star formation indicators

  8. Age dating of supernova remnants

  9. Quantitative constraints on the coupling between star formation and the interstellar medium

  10. Identification and characterization of variable stars

  11. Kinematic decompositions of structural components

  12. Cross-identification of multi-wavelength sources and emission line objects

Top image background courtesy Robert Gendler. Map of individual exposures on GALEX image courtesy Dustin Lang.