J/A+A/709/A140 Hubble Missing Globular Cluster Survey. III. (Libralato+, 2026)
The Hubble Missing Globular Cluster Survey. III. Astro-photometric catalogs,
artificial-star tests, and improved absolute proper motions.
Libralato M., Bellini A., Massari D., Bellazzini M., Aguado-Agelet F.,
Cassisi S., Ceccarelli E., Dalessandro E., Dodd E., Ferraro F.R.,
Gallart C., Lanzoni B., Monelli M., Mucciarelli A., Pancino E., Pascale R.,
Rosignoli L., Salaris M., Saracino S., Zerbinati C.
<Astron. Astrophys. 709, A140 (2026)>
=2026A&A...709A.140L 2026A&A...709A.140L (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Clusters, globular ; Photometry ; Optical ; Infrared
Keywords: photometric - catalogs - astrometry - proper motions -
globular clusters: general
Abstract:
The Hubble Missing Globular Cluster Survey (MGCS) has taken one of the
last opportunities to complete the census of Galactic globular
clusters (GCs) started by past Hubble Space Telescope (HST) programs,
securing high-resolution data for 34 GCs never observed before by HST.
The previous papers of the series have highlighted the astrometric and
photometric potential of the project by analyzing a subsample of
targets. We present, and release to the community, the official
astro-photometric catalogs of the MGCS for all GCs imaged by this
project. We describe the data reduction using state-of-the-art
techniques designed for HST. We discuss the photometric calibration
and show, for the first time, the synergy with the Gaia catalog to
ensure homogeneous photometry across our data set. We compute
artificial-star tests that can be used to assess systematics and the
completeness level of our data. We combined HST and Gaia data to
refine the absolute proper motions of our GCs, reaching a precision ∼3
times better than that of Gaia alone. We used these new proper motions
to update (and to determine for the first time for six systems) the
associations between GCs and their putative galaxy progenitors. This
work continues decades-long efforts of large Treasury programs in
sharing precise and accurate atlases to the community for studying GCs
across a wide range of scientific endeavors.
Description:
Astro-photometric catalogs, artificial-star catalogs and stacked
images of the 34 globular targets part of the MGCS. Fluxes in the
astrometrized stacked images are not properly resampled. Thus, these
images are meant for visual reference only and not for scientific
investigations.
When using this catalog, please cite:
Massari et al. (2025A&A...698A.197M 2025A&A...698A.197M),
Libralato et al. (2026A&A...709A.140L 2026A&A...709A.140L) (this paper) and also
Rosignoli et al. (2026, A&A, in prep.) for NGC6749.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
astroinf.dat 95 32 *Informations on clusters
astro.dat 160 2081515 *Astrometric catalog
phot.dat 100 7538356 Photometric catalog
photzp.dat 34 118 VEGA-magnitude zero-points
astro-io.dat 118 14490889 Input/output positions catalog
phot-io.dat 113 51488860 input/output parameters for photometry
list.dat 127 212 List of fits images
fits/* . 212 Individual fits images
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Note on astroinf.dat: From Massari et al. (2025A&A...698A.197M 2025A&A...698A.197M),
Libralato et al. (2026A&A...709A.140L 2026A&A...709A.140L) (this paper) and
also Rosignoli et al. (2026, A&A, in prep.) for NGC6749.
Note on astro.dat: The coordinates of the center of the cluster used as a
reference and the pixel scale is provided in the astroinf.dat file.
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: astroinf.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Cluster Cluster name
14- 26 F13.9 deg RAdeg Center of the cluster right ascension (J2000)
used as a reference
29- 41 F13.9 deg DEdeg Center of the cluster declination (J2000)
used as a reference
43- 52 F10.4 pix Xref Reference X position
54- 63 F10.4 pix Yref Reference Y position
65- 69 F5.1 mas/pix Scale Pixel scale
71- 79 F9.4 yr Epoch Reference epoch
80 A1 --- Note [*] Note (1)
82- 95 A14 --- SName Simbad name of the cluster
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Note (1): raw and corrected proper motions a robust correction was not possible.
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Byte-by-byte Description of file: astro.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Cluster Cluster name
13- 25 F13.9 deg RAdeg Right Ascension (ICRS) at
reference epoch Ep=Epoch
27- 39 F13.9 deg DEdeg Declination (ICRS) at reference epoch
Ep=Epoch
41- 49 F9.4 yr Epoch Reference epoch of position
51- 60 F10.4 pix x X master-frame position
62- 71 F10.4 pix y Y master-frame position
73- 78 I6 --- Id ID number of the source within the cluster
80- 86 F7.3 mas/yr pmRA ? HST-Gaia raw proper motion
along RA*cos(DE) (1)
88- 93 F6.3 mas/yr e_pmRA ? Error on HST-Gaia raw proper motion
along RA*cos(DE) (1)
95-102 F8.3 mas/yr pmDE ? HST-Gaia raw proper motion along DE (1)
104-109 F6.3 mas/yr e_pmDE ? Error on HST-Gaia raw proper motion
along DE (1)
111-117 F7.3 mas/yr pmRAc ? HST-Gaia corrected proper motion
along RA*cos(DE) (1)
119-124 F6.3 mas/yr e_pmRAc ? Error on HST-Gaia corrected proper motion
along RA*cos(DE) (1)
126-133 F8.3 mas/yr pmDEc ? HST-Gaia corrected proper motion
along DE (1)
135-140 F6.3 mas/yr e_pmDEc ? Error on HST-Gaia corrected proper motion
along DE (1)
142-160 I19 --- GaiaDR3 ? source_id from the Gaia DR3 catalog
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Note (1): This column is included in the catalog only if proper motions were
computed using GaiaHub (see Section 4 of the paper).
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Byte-by-byte Description of file: phot.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Cluster Cluster name
13- 20 A8 --- Inst Instrument
22- 26 A5 --- Filter Filter
28 I1 --- sat Saturation flag (1) (2)
30- 37 F8.4 mag m Calibrated VEGA magnitude (1) (3)
39- 45 F7.4 --- sm Photometric rms (1)
47- 52 F6.4 --- q Quality-of-PSF-fit (QFIT) parameter (1)
54- 64 F11.4 --- o Fractional flux within the fitting radius
prior to neighbor subtraction (1)
66 I1 --- f Number of exposures in which a source
was found (1)
68 I1 --- g Number of exposures used to measure the
flux of a source (1)
70- 77 F8.4 --- rxs Excess or deficiency of flux outside the
core of the star (1)
79- 85 F7.2 --- sky Sky in electrons (optical data) or
electron/s (IR data) (1) (4)
87- 93 F7.2 --- rmssky Sky rms in electrons (optical data) or
electron/s (IR data) (1) (4)
95-100 I6 --- Id ID number of the source within the cluster (5)
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Note (1): All values for a source are set to 0 if the star is not measured in
that filter and camera, and all values but the calibrated magnitude are set
to 0 if a source is saturated in the catalog.
Note (2): The saturation flag is set to 0 for a measurement obtained from a long
exposure, 1 for a measurement obtained from a short exposure, and
9 if the star is saturated (or unsaturated but missed by the second-pass
photometry tool, i.e., likely a spurious detection only included for
completeness; see Section 2 of the paper).
Note (3): The VEGA-magnitude zero-point is provided in the photzp.dat file.
Note (4): To estimate the significance of a source over the sky, first convert
calibrated VEGA magnitudes into instrumental fluxes (in unit of
electrons or electron/s for optical and IR data, respectively):
flux = 10(-0.4*(m-ZPVEGAmag)^).
Note (5): The ID number is the same as in the corresponding astrometric catalog.
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Byte-by-byte Description of file: photzp.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Cluster cluster name
13- 20 A8 --- Inst Instrument
22- 26 A5 --- Filter Filter
28- 34 F7.4 mag ZP VEGA-magnitude zero-point
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Byte-by-byte Description of file: astro-io.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Cluster Cluster name
13- 25 F13.9 deg RAi Input right ascension (1)
27- 39 F13.9 deg DEi Input declination (1)
41- 50 F10.4 pix xi Input X master-frame position (1)
52- 61 F10.4 pix yi Input Y master-frame position (1)
63- 75 F13.9 deg RAo Output right ascension (1)
77- 89 F13.9 deg DEo Output declination (1)
91-100 F10.4 pix xo Output X master-frame position (1)
102-111 F10.4 pix yo Output Y master-frame position (1)
113-118 I6 --- Id ID number of the source
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Note (1): The coordinates of the center of the cluster and the pixel scale are
the same as in the analog astrometric catalog with real sources.
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Byte-by-byte Description of file: phot-io.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Cluster Cluster name
13- 20 A8 --- Inst Instrument
22- 26 A5 --- Filter Filter
28- 34 F7.4 mag mi Input calibrated VEGA magnitude (1) (2)
36- 42 F7.4 mag mo Output calibrated VEGA magnitude (1) (2)
44- 56 F13.4 --- smo Output photometric rms (1)
58- 65 F8.4 --- qo Output quality-of-PSF-fit (QFIT) parameter (1)
67- 77 F11.4 --- oo Output fractional flux within the fitting
radius prior to neighbor subtraction (1)
79 I1 --- fo Output number of exposures in which a
source was found (1)
81 I1 --- go Output number of exposures used to measure
the flux of a source (1)
83- 90 F8.4 --- rxso Output excess or deficiency of flux outside
the core of the star (1)
92- 98 F7.2 --- skyo Output sky in electrons (optical data)
or electron/s (IR data) (1)
100-106 F7.2 --- rmsskyo Output sky rms in electrons (optical data)
or electron/s (IR data) (1)
108-113 I6 --- Id ID number of the source (3)
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Note (1): All values for a source are set to 0 if the star is not measured in
that filter and camera.
Note (2): The VEGA-magnitude zero-point is provided in the photzp.dat file,
and it is the same as for the analog photometric catalog with real stars.
Note (3): The ID number is the same as in the corresponding artificial-star
astrometric catalog.
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Cluster Cluster name
13- 21 F9.5 deg RAdeg Right Ascension of center (J2000)
22- 30 F9.5 deg DEdeg Declination of center (J2000)
32- 35 F4.2 arcsec/pix scale Scale of the image
37- 41 I5 --- Nx Number of pixels along X-axis
43- 47 I5 --- Ny Number of pixels along Y-axis
49- 55 I7 Kibyte size Size of FITS file
57- 89 A33 --- FileName Name of FITS file, in subdirectory fits
91-127 A37 --- Title Title of the FITS file
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Acknowledgements:
Mattia Libralato, mattia.libralato(at)inaf.it
References:
Massari et al., Paper I 2025A&A...698A.197M 2025A&A...698A.197M
Rosignoli et al., Paper II in prep.
License: CC-BY-4.0
(End) Patricia Vannier [CDS] 09-Apr-2026