Open Cluster in Sagittarius
Messier 21 is small open cluster located just northeast of the Trifid Nebula (Messier 20). It is also known as Webb's Cross. I have trouble seeing a cross shape in this group of stars, although there are some strings of stars stretching out in several directions. This is a pretty cluster consisting af a few sparkling bright stars and many smaller ones. The surrounding region is filled with many star clusters and nebulae, with the famous Lagoon Nebula (Messier 8) just about 2 degrees to the south.
| Magnitude | 5.9 |
| Apparent Size | 15' |
| Distance (light yrs) | 4,100 |
| Right Ascension | 18:04.2 |
| Declination | -22 30 |
| Field of View | 29' x 22' |
Image details: Exposure times of 10 minutes each of luminance, red, green, and blue, taken with an SBIG STF-8300M imager and a 14" Meade LX850 telescope at f/5.5.
October 2023