B 86 (LDN 93) and NGC 6520 (Lund 805, Cr 361) Dark Nebula and Open Cluster in Sagittarius

Center of field at approximately: RA 18 hours 03 minutes 11 seconds, Dec -27 degrees 51 minutes 48 seconds

Size: 5.0' and 6.0' (5.0') Magnitude: -- and 7.6 Class: 5 Ir G and I 2 r n

North is up

West to the right


 8" f5 Newtonian reflector


 ST-8XME, self-guided, binned 1x1, temp -15c, camera control MaxIm DL 4.53


 Red (Hoya 25A) filter, 150 minutes (15 x 10 minute subs), 07/15/2006: seeing 3.7-4.2 per CCDStack


CCDStack 2.75.4973.15338, Photoshop CS5.1


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


This is currently the lowest field I have imaged from my home... it just barley cleared the top of the tree to my South (this image shot in 2006 ... I can no long image this low in 2013).

Re-processed this sequence in December 2013, with newer versions of CCDStack and Photoshop.

According to "Star Clusters", by Brent Archinal and Steven Hynes, the size of the open cluster is 5.0 arc minutes.

This description from the on-line Edward Emerson Barnard "A Photographic Atlas of Selected Regions of The Milky Way":

α(2000)18h 03m 02s, δ(2000) -27 53
Galactic Coordinates 3, -3
 Diam. 5, several small stars in it, the cluster NGC 6520 close E, CD-2712302 (7.4 mag) on NW edge. For the visual discovery of this object see Astronomische Nachrichten 108, 370, 1884.