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Mission Overview

Formation History of Ultra-Faint Dwarf Galaxies (FHUFD)

Primary Investigator: Tom Brown

HLSP Authors: Tom Brown

Released: 2018-01-24

Updated: 2018-01-24

Primary Reference(s): Brown et al. 2014

DOI: 10.17909/T99H5G

Citations: See ADS Statistics

Read Me

FHUFD image of Leo IV
Color image of Leo IV. Image source:


The following proposals are relevant to this HSLP: HST Program 12549

FHUFD is a deep, high-precision, photometric survey of six ultra-faint dwarf galaxy satellites of the Milky Way, in order to discern any cosmologically-driven synchronization of their formation histories. For six ultra-faint dwarf satellites of the Milky Way (Bootes I, Coma Berenices, Canes Venatici II, Hercules, Leo IV, and Ursa Major I), the team provides ACS photometry, astrometry, and co-added (drizzled) images. The photometry and images are in two bands: F606W (broad V) and F814W (I), using the STMAG photometric system. The astrometry is given in equatorial coordinates (degrees, J2000). The drizzled images have a scale of 0.03 arcsec/pix. The images from each pointing are contained in their own FITS files. Each galaxy also has a single catalog file containing the point sources detected in the images.

Data Products

The drizzled images are stored as FITS files with the following naming convention:



  • <galaxy> = name of the galaxy, e.g., "ursamajori"
  • <##> = the pointing number, as a two-digit zero-padded integer
  • <filter> = the filter used, either "f606w" or "f814w"

The source catalogs follow a similar naming convention, except there is no pointing number component, and the string "multi" is used instead of the filter. The extension for the source catalogs is "*cat.fits".

Data Access

Both the catalogs and the image products are available via the direct download links below. The image observations are also available in the MAST Portal and astroquery. Set the 'Provenance Name' filter to FHUFD in the Portal Advanced Search to match all observations. The observations can also be retrieved programmatically using the astroquery.mast module. The code example below retrieves all products and allows you to download them via a bash script.

from astroquery.mast import Observations
all_obs = Observations.query_criteria(provenance_name="fhufd")
data_products = Observations.get_product_list(all_obs)
Observations.download_products(data_products, curl_flag=True)
  • A web-based interface for cross-mission searches of data at MAST or the Virtual Observatory
  • Search for and retrieve FHUFD data products programmatically.
Field R.A. (J2000) Dec. (J2000) Exptime F606W (sec) F814W (sec) Images Catalogs
Bootes I 14:00:04 +14:30:47 2340 2200 FITS Files  Source Catalog
Canes Venatici II 12:57:10 +34:19:23 20850 20850 FITS Files Source Catalog
Coma Berenices 12:27:21 +23:53:13 2340 2200 FITS Files Source Catalog
Hercules 16:31:05 +12:47:07 12880 12745 FITS Files Source Catalog
Leo IV 11:32:57 -00:31:00 20530 20530 FITS Files Source Catalog
Ursa Major I 10:35:04 +51:56:51 4215 3725 FITS Files Source Catalog



Please remember to cite the appropriate paper(s) below and the DOI if you use these data in a published work. 

Note: These HLSP data products are licensed for use under CC BY 4.0.