FreeLists / az-observing / [AZ-Observing] NGC 6645 Cluster in Sagitarrius

["Steve Coe" <stevecoe@xxxxxxxxx>]

Howdy all;

Several months ago one of my observing buddies for many years, Curt Taylor, 
died from a blood clot problem.  I purchased a 6 inch f/6 Orion (Intes) 
Maksutov-Newtonian from his estate with the idea of using it as an RFT.  It 
took a while to get it mounted up on my Losmandy G-11 mount, but now that it is 
all working I am very pleased with the results.  On Thursday evening at the 
Flatiron site near Phoenix, AZ I had a good Summer night and observed a variety 
of Milky Way objects.  The seeing was 6/10 and the transparency 5/10.  Just me 
and all those Summer goodies.  Thanks Curt.

One of the surprises of the night was NGC 6645, an open cluster.  With the 22mm 
Panoptic it was bright, large, showed 12 stars of mags 10 and 11, pretty 
compressed and had an irregular figure.  This cluster was just a faint fuzzy 
spot in the 10x50 finder, but stood out well from the Milky Way with the 22mm 
eyepiece.  Moving up to the 8.8mm UWA eyepiece brought out 18 stars, some very 
faint.  The bizarre figure of this cluster now became evident.  There is a dark 
spot within the cluster that takes up about 40% of the entire cluster size.  
This interesting feature is on the south side of the cluster, but well within 
the cluster of stars.  The highest power I used was the 6.7mm and this showed 
off the dark area prominently and revealed a dozen faint stars surrounding the 
dark pool within the cluster.  This ring of stars surrounded the "Black Lagoon" 
and therefore really highlighted it.  Put this fascinating cluster on your list 
for the Summer, it is worth the time.

Clear Skies to us all;
Steve

stevecoe@xxxxxxxxx
Author:  Deep Sky Observing--The Astronomical Tourist
Saguaro Astronomy Club web site:
www.saguaroastro.org


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