←MLO  Globular Clusters
 Observed for the
Astronomical League's Globular Cluster Observing Program

Marie Lott, Atlanta, GA
Atlanta Astronomy Club
Updated 10/14/17 12:39 PM -0400

This program documents 50 globular clusters with an estimate of their different core concentration.
The most dense globular cluster has a Shapley-Sawyer class of I; the most diffuse globular cluster has a class of XII.
Click any of the images on the right side of the page to see my object observation log and larger photos for each cluster.
Class descriptions and examples (below left) are taken from Wikipedia and astronomyforum.net.

  

      

Shapley-Sawyer Classification Standards
 My image collection
click each thumbnail for observation details
Example Class Description
Classes I through III – The clusters contain a highly visible stellar concentration at the core, with a surrounding halo that decreases in luminosity as the distance from the core increases.
M75
M75		 I High concentration toward the center
M75
M 75		      
M2
M2		 II Dense central concentration   M80 - click for more
M 80		 NGC 6356
NGC 6356		 M2
M 2		  
M54
M54		 III Strong inner core of stars   NGC362 - click for more
NGC 362 		 47 Tuc
47 Tuc		 NGC 6388
NGC 6388		 NGC 6441
NGC 6441
  III     NGC 6541
NGC 6541		 M 54
M 54		    
Classes IV through VI – The core’s stellar concentration is still visible, but is more spread out and not as dense. 
M15
M15		 IV Intermediate rich concentrations  
 		 M62
M 62		 NGC 6293
NGC 6293		 M28
M 28		 M92
M 92
  IV     NGC6517
NGC 6517		 M 15
M 15		 NGC 6342
NGC 6342		  
M30
M30		 V Intermediate concentrations  
 		 M 69
M 69		 M 30
M 30		 M70
M 70		 M13
M 13
  V     NGC 6544
NGC 6544		      
M3
M3		 VI Intermediate  
 		 NGC 6522
NGC 6522		 NGC 6624
NGC 6624		 NGC 6752
NGC 6752		  
Classes VII through IX – Stellar concentration is more homogenous & less contrasted 
M22
M22		 VII Intermediate  
  		NGC 5986
NGC 5986		 NGC 6723
NGC 6723		 M 22
M22		 M10
M 10
M14
M14		 VIII Rather loosely concentrated towards the center   Omega Centauri
Omega Cen		 NGC 6584
NGC 6584		 M 19
M 19		 M14
M 14 
  VIII     NGC 6717 (Palomar 9)
Palomar 9		 M 9
M 9		 NGC 6401
NGC 6401		 NGC 6934
NGC 6934
M12
M12		 IX Loose towards the center   M4
M 4 		NGC 6397
NGC 6397		 M12
M 12		 M72
M 72
  IX     NGC6712
NGC 6712		      
Classes X through XII – The cluster surface luminosity is beocmng totally homogeneous with no display of concentration at the core.
M68
M68		 X Loose  

NGC 6362
NGC 6362		 M 107
M 107
Palomar 8
Palomar 8		 NGC6539
NGC 6539
  X     NGC 288
NGC 288		 M 71
M 71 (X/XI)		    
M55
M55		 XI Very loose towards the center  
  		NGC 6352
NGC 6352		 NGC 6496
NGC 6496		 NGC 6366
NGC 6366 		 M55
M 55
  XI     NGC 6535
NGC 6535		 M 71
M 71 (X/XI)		 NGC 6553
NGC 6553		  
Palomar 12
Palomar 12		 XII Almost no concentrations towards the center  
  		Palomar 11
Palomar 11		 Palomar 7
Palomar 7