The Missing Globular Clusters Survey (MGCS)

27/01/2026 Page maintained by Michele Bellazzini - Last updated on 28/01/2026

The Missing Globular Clusters Survey (MGCS)

The Hubble Space Telescope Missing Globular Clusters Survey (MGCS) is an HST Treasury Programme (Cycle 31 #17435) aimed at collecting deep, high spatial resolution imaging, astrometry, and photometry for 34 globular clusters (GCs) of Milky Way that were previously unobserved with HST. The main goal of the survey is to fill a significant hole in our knowledge of the GC system of our own Galaxy. Indeed MGCS targets constitute more than 20% of the entire GC population of the Milky Way. GCs are wonderful tracers of galaxy formation and precious witnesses of the earliest phases of the evolution of galaxies, in particular because their age can be inferred with great precision if accurate deep photometry is available. The project is being complemented by analogous HST observations for 13 additional Galactic GCs  that were also lacking  adequate HST coverage (Cycle 33 #18025).  HST still has unrivalled capabilities for the study of Milky Way globulars. As the operational life of the telescope is approaching its end it becomes more and more urgent to complete the survey of all known Galactic GCs.

For this reason MGCS and its extension have an enormous heritage value.

Galactic Globular clusters in the Mass vs. Size diagram. The MGCS targets are highlighted and labelled. Data from H. Baumgardt’s database.

For the treasury programme we are committed to provide the catalogues with photometry and astrometry for all the target clusters (observed with the Wide Field Channel of the Advanced Camera For Surveys) and the associated parallel fields (observed with the UVIS channel of the Wide Field Camera 3. For a handful of highly extinct clusters observations were carried on with the IR channel of the WFC3, with no parallel fields), as well as some useful software products that will be made publicly available through this page.

The detailed plan of the survey with sone examples of the science we are interested in can be found in the first paper of the MGCS series, presenting the project: Massari et al. (2025).

MGCS image of the centre of NGC6749

MGCS People

PI: Davide Massari (INAF-OAS Bologna),

Co-PI: Michele Bellazzini (INAF-OAS Bologna), Mattia Libralato (INAF-OA Padova),

Co-I: F. Aguado-Agelet (Univ. Vigo/ Univ. La Laguna),  A. Bellini (STScI Baltimore), S. Cassisi (INAF OAA / INFN Pisa), E. Ceccarelli (UniBo/INAF OAS Bo),  E. Dalessandro (INAF OAS Bo), E. Dodd  (Univ. Durham),     F. R. Ferraro (UniBo),  E. R. Garro (ESO Santiago), C. Gallart (IAC / Univ. La Laguna), B. Lanzoni  (UniBo), M. Monelli (INAF OAA/ IAC / Univ. La Laguna), A. Mucciarelli (UniBo), E. Pancino (INAF OA Arcetri), R. Pascale (INAF OAS Bo), L. Rosignoli (UniBo/INAF OAS Bo), M. Salaris (INAF OAA / Univ. JM Liverpool), S. Saracino (INAF OA Arcetri / Univ. JM Liverpool)

MGCS Publications

  1. Massari, D., et al., 2025, The Hubble Missing Globular Cluster Survey: I. Survey overview and the first precise age estimate for ESO452-11 and 2MASS-GC01, A&A, 698, A197
  2. Garro, E.R, et al. 2026, HST+IGRINS synergy to characterise the newly discovered metal-rich bulge globular cluster Patchick 126, A&A, in press,
  3. Rosignoli, L., et al., 2026, The Hubble Missing Globular Cluster Survey. II. Survey membership tools and kinematic analysis of NGC 6749 ,A&A, in press, arXiv:2512.01530

MGCS Data

All MGCS images are collected at MAST under the DOI number 10.17909/ncwh-db07

Catalogues will be added soon.

MGCS Products