M10 – M12, a duo of globular clusters.

With the approach of the summer, the binocular observer can direct his attention to a target rich environment: the Milky Way. A nice introduction is made by the appearance of numerous globular clusters. The constellation Ophiuchus harbors many of them. Charles Messier alone discovered seven globulars in Ophiuchus. Two of these Messier globulars, M10 and M12, form a nice paring in the binocular field. First try to locate the 4.8 magnitude star 30 Ophiuchus in the torso of the Serpent Bearer. M10 can be found at 1° west of 30 Oph. Once M10 is centered in the pair of binoculars, look for M12 at 3 Ľ ° northwest of M10. Now that they are visible in the same field of view, these two globulars form an interesting pair to study more profoundly. At first glance, all globulars do look the same, don’t they? Now take a second look. I do find M10 the brightest of the two, but with a very small difference. It is also the one with the ‘sharpest’ core and the largest halo. M12 looks a tad paler and shows a ‘softer’ core. While M10 has a distance of 14,000 l-y, M12 is 16,000 l-y away.
The brightest star in the sketch is 30 Ophiuchus.

Site : Butgenbach, Belgium
Date : May 5, 2008
Time : around 23,30UT
Binoculars : Bresser 8x56
FOV: 5.9°
Filter : none
Mount : Trico Machine Sky Window
Seeing : 2,5/5
Transp. : 4/5
Nelm : 6.0
Sketch Orientation : N up, W right.
Digital sketch made with Photo Paint, based on a raw pencil sketch.

(Note: if the sketch does look too dark on your monitor, try to darken the room.)