| Synopsis: Also known as M4; globular cluster;
located in Scorpius, near a Scorpii (Antares); R.A.
16:23.6, dec. -26:32; culmination June-July; magnitude 5.9; distance £
2000 pc (~6500 light years). |
|
| Description: A large and
relatively loosely clustered globular cluster with a noticeable bar of stars across the
centre and lacking a strong central concentration. It has a visual diameter of 14' and a
photographic diameter of about 23' which corresponds to 40 light years. M4 is
possibly the closest globular cluster to the earth, at a distance of less than 2000
pc (~6500 light years). |
|
| Property |
Value |
Notes/References |
| IAU |
|
|
| R.A. |
16:23.6 |
|
| Declination |
-26:32 |
|
| Precession in RA |
|
|
| Precession in dec. |
|
|
| Proper Motion RA |
|
Includes the cos(dec) term. |
| Proper Motion dec |
|
|
| Radial Velocity |
|
|
| Parallax |
|
|
| Distance |
£ 2000 pc |
Malin & Frew 1995 |
| mv |
|
|
| Mv |
|
|
| B-V |
|
|
| Table 1: Known physical parameters for NGC
6121. |
|
|
| Observation: Visible in 7 x 50 mm binoculars
under dark skies as a large faint disk, brightening slightly towards the
centre. Although NGC 6121 lacks a bright core like that of NGC
5139, it is nevertheless unmistakable. 100 mm aperture will begin to resolve
individual stars and reveal a central bar. |
|
Astronomy
Page >> Some Southern Objects >> NGC 6121