Article · Wikipedia archive · Last revised Jun 13, 2026

Mercer 3

Mercer 3, also known as GLIMPSE-C02, is a heavily obscured globular cluster embedded in the disk of the Milky Way galaxy. It was discovered in 2008 in the data obtained by 2MASS and GLIMPSE infrared surveys, and independently characterized by two groups. The cluster is located in the Scutum constellation. It had avoided detection for such a long time due to the extremely strong foreground extinction in its direction reaching 24 magnitudes in the visible light. Mercer 3 is probably situated at the distance from 4 to 8 kpc from the Sun and has a half-light radius of 0.7–1.5 pc.

Last revised
Jun 13, 2026
Read time
≈ 1 min
Length
228 w
Citations
11
Source
Mercer 3
2MASS image of Mercer 3
Observation data (J2000 epoch)
ConstellationScutum
Right ascension18h 18m 30s1
Declination−16° 58′ 36″1
Distance13–26 kly (4–8 kpc1)
Apparent magnitude (V)not visible
Apparent dimensions (V)39″ (half-light diameter)1
Physical characteristics
Mass(2–3)×105 M
Radius2–5 ly
Estimated age12 Gyr1

Mercer 3, also known as GLIMPSE-C02, is a heavily obscured globular cluster embedded in the disk of the Milky Way galaxy.1 It was discovered in 2008 in the data obtained by 2MASS and GLIMPSE infrared surveys, and independently characterized by two groups.12 The cluster is located in the Scutum constellation. It had avoided detection for such a long time due to the extremely strong foreground extinction in its direction reaching 24 magnitudes in the visible light. Mercer 3 is probably situated at the distance from 4 to 8 kpc from the Sun and has a half-light radius of 0.7–1.5 pc.1

Mercer 3 is an old globular cluster having the age of about 12 billion years. The mass of cluster is estimated at 2–3 hundred thousand solar masses.1 It is among the most metal-rich galactic globular clusters known.2

References

References

  1. Strader, J.; Kobulnicky, H. A. (2008). "A Probable New Globular Cluster in the Galactic Disk". The Astronomical Journal. 136 (5): 2102. arXiv:0808.1719. Bibcode:2008AJ....136.2102S. doi:10.1088/0004-6256/136/5/2102. S2CID 12924612.
  2. Kurtev, R.; Ivanov, V. D.; Borissova, J.; Ortolani, S. (2008). "Obscured clusters. II. GLIMPSE-C02 – A new metal rich globular cluster in the Milky Way". Astronomy & Astrophysics. 489 (2): 583–587. arXiv:0808.1565. doi:10.1051/0004-6361:200809425. S2CID 14312617.