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Mission Overview

HST Photometry and Astrometry of the Bootes I Ultrafaint Dwarf Galaxy (BOOCATS)


Primary Investigator: Imant Platais

HLSP Authors: Carrie Filion, Imants Platais, Rosemary Wyse, Vera Kozhurina-Platais

Released: 2022-09-27

Updated: 2022-09-27

Primary Reference(s): 

DOI: 10.17909/g37r-1r51

Citations: See ADS Statistics

Read Me

Source Data:

Color-Magnitude and Proper-Motion diagrams

Left: A color (apparent) magnitude diagram of the sources in the photometric catalog that are likely stellar members of Bootes I (selected to have P_mem > 0.5).

Right: A vector-point diagram showing the relative proper motions of a subset of brighter sources in the astrometric catalog.



Bootes I is a nearby, relatively bright ultrafaint dwarf galaxy. This dataset consists of two catalogs of sources in the line-of-sight to this ultrafaint galaxy, produced from deep, optical imaging in three fields, taken with the Hubble Space Telescope Advanced Camera for Surveys, Wide Field Camera in the F606W and F814W filters. The first catalog contains photometry that the team produced for the sources in the field. The second catalog contains relative proper motions for a subset of the brighter sources, which could be measured with a baseline of ~7 years thanks to the existence of earlier-epoch, archival imaging.

Data Products

The data file naming convention for the catalog files is:


Data file types:

_photometric-catalog.csv Catalog containing HST photometry in the Vega magnitude system
_astrometric-catalog.csv Catalog containing relative proper motions

Data Access


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.