| Mercer 3 | |
|---|---|
 2MASS image of Mercer 3 | |
| Observation data (J2000 epoch) | |
| Constellation | Scutum |
| Right ascension | 18h 18m 30s[1] |
| Declination | −16° 58′ 36″[1] |
| Distance | 13–26 kly (4–8 kpc[1]) |
| Apparent magnitude (V) | not visible |
| Apparent dimensions (V) | 39″ (half-light diameter)[1] |
| Physical characteristics | |
| Mass | 2–3 × 105 M☉ |
| Radius | 2–5 ly |
| Estimated age | 12 Gyr[1] |
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.[1][2] 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]