J/A+A/705/A244 CANDiSC cluster detections in VVVX (Obasi+, 2026)
Consensus-based Detection of the nonparametric detection of star clusters
(CANDiSC).
Obasi C.O., Fernandez-Trincado J.G., Gomez M., Minniti D., Alonso-Garcia J.,
Ferreira B.P.L., Garro E.R., Dias B., Saito R.K., Barbuy B., Parisi M.C.,
Palma T., Tang B., Ortigoza-Urdaneta M., Baravalle L.D., Alonso M.V.,
Mauro F.
<Astron. Astrophys. 705, A244 (2026)>
=2026A&A...705A.244O 2026A&A...705A.244O (SIMBAD/NED BibCode)
ADC_Keywords: Infrared sources ; Photometry ; Surveys
Keywords: Galaxy: bulge - Galaxy: disk - Galaxy: general -
globular clusters: general - open clusters and associations: general
Abstract:
The VISTA Variables in the Via Lactea (VVV) and its eXtension VVVX are
near-infrared surveys mapping the Galactic bulge and adjacent disk.
These datasets have enabled the discovery of numerous star clusters
obscured by high and spatially variable extinction. Most previous
searches relied on visual inspection of individual tiles, which is
inefficient and biased against faint or low-density systems.
We aim to develop an automated and homogeneous algorithm for
systematic cluster detection across different surveys. Here we apply
our method to VVVX data covering low-latitude regions of the Galactic
bulge and disk, affected by extinction and crowding.
We introduce the Consensus-based Algorithm for Nonparametric Detection
of Star Clusters (CANDISC), which integrates kernel density estimation
(KDE), density-based spatial clustering (DBSCAN), and
nearest-neighbour density estimation (NNDE) within a consensus
framework. A stellar overdensity is classified as a candidate when
identified by at least two of these methods. We apply CANDISC to 680
tiles in the VVVX PSF photometric catalogue, covering approximately
1100 square degrees.
We detect 163 stellar overdensities, of which 118 correspond to known
clusters. Cross-matching with recent catalogues yields five additional
matches, leaving 40 likely new candidates not present in previous
compilations. The estimated false-positive rate is below five percent.
CANDISC offers a robust and scalable approach for detecting stellar
clusters in deep near-infrared surveys, successfully recovering known
systems and revealing new candidates in the obscured and crowded
regions of the Galactic plane.
Description:
This catalogue compiles star cluster candidates identified in the VVV
and VVVX near-infrared surveys, including those found with the CANDISC
detection algorithm. CANDISC integrates three nonparametric density
estimators (KDE, DBSCAN, and NNDE) within a consensus framework. A
stellar overdensity is retained as a candidate when detected by at
least two of the three methods.
The input dataset consists of 680 VVVX PSF-photometry tiles
reprocessed with DoPHOT (Alonso-Garcia et al., in prep.), covering
approximately 1100 square degrees of the Galactic disk outside the
inner bulge. The compilation of known VVV/VVVX clusters contains 788
entries (table1). CANDISC recovers 163 overdensities (table2), of
which 118 correspond to known clusters and 40 appear to be new
candidates not previously catalogued (table3).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea3.dat 41 788 Compilation of known VVV/VVVX clusters
tablea2.dat 73 163 CANDISC detections with cross-match flags
tablea1.dat 61 40 New cluster candidates detected in VVVX
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See also:
II/376 : VISTA Variable in the Via Lactea Survey (VVV) DR4.2
(Minniti+, 2023)
J/MNRAS/481/3902 : New Galactic clusters in the VVVX disc area
(Borissova+, 2018)
J/A+A/689/A148 : VVVX tile coordinates (Saito+, 2024)
J/ApJS/262/7 : 886 nearby star clusters (He+, 2022)
J/ApJS/265/12 : Neighboring open clusters with Gaia DR3 (Qin+, 2023)
J/A+A/673/A114 : Improving the open cluster census. II. (Hunt+, 2023)
Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
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1- 15 A15 --- Cluster Cluster identifier
17- 28 F12.7 deg RAdeg Right ascension (ICRS)
30- 41 F12.7 deg DEdeg Declination (ICRS)
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Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Tile VVV/VVVX tile name
14- 25 F12.7 deg RAdeg Right ascension (ICRS)
27- 38 F12.7 deg DEdeg Declination (ICRS)
40- 73 A34 --- LitName Literature counterpart name
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Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Cluster Cluster identifier
17- 22 A6 --- Tile VVVX tile name
24- 33 F10.3 deg RAdeg Right ascension (ICRS)
35- 45 F11.3 deg DEdeg Declination (ICRS)
47- 49 I3 --- A Count (0.4-1.4 mag)
51- 53 I3 --- B Count (0.3-1.4 mag)
55- 57 I3 --- C Count (0.6-2.0 mag)
59- 61 I3 --- D Count (0.5-1.4 mag)
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Acknowledgements:
From Casmir Obasi, casmiroluabuchukwuobasi(at)gmail.com
This work was funded by the Postdoctoral Talent Attraction Competition
for Research Centers and Institutes of the Universidad Andres Bello
(UNAB) 2025. Support was provided under grant No. DI-07-25/ATP.
(End) Patricia Vannier [CDS] 05-Dec-2025