Double star in Ursa Major
Messier 40 is of interest strictly for historical reasons. Whereas most of the objects on Messier's list are impressive deep-sky objects, Messier 40 is just a mundane double star (the pair of bright stars to the upper left in this picture). Remember that Messier's purpose was not to list spectacular deep-sky objects, but to catalog objects that might be mistaken for comets in a small telescope. Apparently he decided that this pair of faint stars could lead to such confusion under some viewing conditions. Nowadays, few observers spend much time looking at Messier 40, but if you want to observe all the Messier objects (and many amateur astronomers do), you will have to hunt down this double star sooner or later.
Once locating Messier 40, it is a short step to two small galaxies. NGC 4290 (magnitude 12.9) and the more challenging NGC 4284 (magnitude 14.3) are just about 1/4 degree away.
| Magnitudes | 9.7, 10.1 |
| Separation | 53" |
| Distance (light yrs) | 510? |
| Right Ascension | 12:22.2 |
| Declination | +58 05 |
Image details: 10 exposures, each 60 seconds at ISO 1600, taken with a Canon 400D camera and a Meade 12-inch telescope at f/5.4.
May, 2009