M4, Globular Cluster In Scorpius
M4 is one of the closest globular clusters, perhaps the closest, at 6500 light years from Earth. It has a relatively low luminosity, probably related to the relatively small number of stars—estimated at 44,000. It lies close to Antares and is thus easy to find with binoculars.
| Date | 2001-06-15 |
| Scope | RCOS Ritchey-Chretien 12.5 inch at f6.75 on A-P 1200GTO mount |
| Exposure | One, on hypered Supra 400 film, 45 min with IDAS filter |
| Processing | Stretched and unsharp masked in PhotoShop |