M 10 (NGC 6254, GCL 49) Globular Cluster in Ophiuchus

Located at: 16 hours 57 minutes 09 seconds, Dec -04 degrees 05 minutes 58 seconds

Size: 20' Magnitude: 6.6 Class: 7

North is up

West to the right


 14.5" f5 Newtonian reflector


ST-8XME, self-guided, binned 1x1, temp -15c, camera control MaxIm DL 4.54


Lumicon Red filter,  330 minutes  (33 x 10 minute subs), 07/17/18/2014; seeing 2.4-3.8 FWHM per CCDStack


CCDStack 2.80.5308.25197, Photoshop CS5.1


Rolling Roof Observatory, Thousand Oaks, California 91360 (+34d 13m 29s -118h 52m 20s)

Notes: Based on the listed size of 20' in Megastar (v 5.0.14), the outlying stars of this cluster overfill my horizontal field of view (~17'). See the 8" version.

From the NGC / IC Project:

Contemporary Visual Observation(s) for NGC 6254

NGC 6254 = M10
16 57 08.9 -04 05 58
V = 6.6;  Size 15.1

17.5" (7/15/99): beautifully resolved at 220x.  The halo appears to extend to 
nearly 14' although the star density is very low in the outer edge of the halo.  
The inner halo is sharply concentrated with a very bright 5'x4' core which is 
elongated SW-NE.  The cluster is highly resolved into mag 12/13 stars from edge 
to edge with the stars very densely packed over the core.  A second layer of mag 
13/14 stars is superimposed over the core.  The halo contains a number of 
strings including a long string to the south which curves east and a string to 
the north which curves west.  Also two parallel linear strings head N or NNE 
from the core.

13": very bright, fairly large, intense core richly covered with fairly bright 
stars.  Scores of stars are resolved in the outer halo.

8": bright lively core highly resolved.  The outer halo is highly resolved with 
several long, distinct streamers.

- by Steve Gottlieb