The Great Hercules Cluster (Messier 13) - Sketch

object details: "Hercules Globular Cluster" - M 13
size: 20' ;  magnitude: 5.8m ;  distance: 25kly ;  constellation: Hercules .

Location and conditions: Negev desert (Nahal Barak), Israel, ~6.8 mag. sky.
Time and date: 6-7/05/2011 , 00:00.
Instrument: Orion skyview pro 8" F/5 Newtonian. 5mm Vixen LVW eyepiece (200X).
Drawing details: Graphite pencil sketch on a white paper, made while observing with a telescope under red light. Sketch is north oriented. Scanned, inverted and processed in Photoshop. Observer: Michael Vlasov.

Notes:
The most prominent globular cluster in northern sky. Very rich, bright (was easily visible to a naked eye), comopsed of relatively bright stars and can be resolved to individual stars (the brightest of them) at magnifications over 100-150x. Unlike most globulars - M13's structure is quite complex, with several "streaks" formed by star chains and dark lanes. The famous "propeller" shaped by three small dark lanes can be seen on this sketch at cluster's right side (west off the core).

Original drawing: