M4 is a fine globular star cluster, one of the largest and closest of 
its type.  It is located about 1.3 degrees directly west of the star 
Antares in the constellation Scorpius.  Located quite easily in 
binoculars, it may even be a naked eye object under good sky conditions.

M4 was probably first observed by P.L. de Cheseaux in 1746.  Messier. 
originator of the famous Messier catalog, observed it in 1764.  The 
distance to M4 is approximately 5700 light years, making it one of the 
closest of the globular clusters.

This image of M4 has been log scaled to bring out detail and to compress 
the brightness range of the image so that it more closely resembles that 
of photographic film.   The digital image processing was done by Ben 
Cushwa and Dr. Greg Latta of Frostburg State University. 

Object: M4 (NGC 6121)
Coordinates: Right Ascension 16hr 20.6m, Declination -26deg 24m
Constellation: Scorpius
Size: 23 minutes of arc
Magnitude: 6

Telescope focal length: 500mm
Telescope aperture: 80mm
Camera: Santa Barbara Instruments ST-6
Exposure: 400s (20 @ 20s), cropped sum of two 200s exposures
Observer(s): Greg and Teddy Latta