Monday, November 11, 2013

Double Cluster in Perseus

In my beginnings most of the DSO’s that I sketched where found by accident. I had not known how to locate them in the sky because I did not see all the stars that formed constellations shape and I was too new to stargazing to remember the locations of the important stars in the sky. I started stargazing by learning the shapes of the constellations from a book called “The Stars, a new way to see them” from H.A. Rey in which most of constellation shapes looks like they should according their names.  

That book was part of my wife’s baggage when we lived in the Colombian Amazon Jungle. Therefore, she brought me into this entire marvelous world of astronomy. On a clear night without moon we used to go out and spot the constellations by comparing the stars seen to the ones in the book mentioned above.  It was so dark that we had to use a red light to even see each other well. I wish we could be there once again, and could see once again the majestic Magellanic Clouds rising around 15° over the horizon.

Now, let´s talk about the sketch. The only stars well visible to the naked eye from my LP sky were the ones that form Cassiopeia´s “m” shape. The easiest way to find the double cluster was by tracing a straight line from Navi (γ Cas) to Ruchbah (δ Cas) and going beyond Ruchbah 3 times that distance.
Also known as C14 in the Caldwell catalogue, this double cluster was first catalogued by the Greek astronomer Hyparcos on 130 B.C. Tycho Brahe measured one position for this object described as a “nebulous star” and sometime later Johann Bayer designated that star as Chi and he probably designated a fainter nearby star as h. However, each cluster is actually designated also with one of those two letters: h for NGC 869 and chi for NGC 884.

This DSO is 7000 Ly away from us and easy to recognize because it is large and dense. There is a half arc degree between the centers of each cluster (a few hundred Ly). A large amount of unresolved stars in the binocular view form two nebular-like spots around two principal groups of stars:  HIP 11020, HIP 11098 and HIP 11115 almost make an equilateral triangle in NGC 884; and the duplet of HIP 10805 and HIP10816 in NGC 869.  There is second pair of stars accompanying the clusters, but I thought they are not part of the clusters, they are HIP10624 and HIP 10633.  However this third group finishes a remarkable shape of the whole DSO in the binoculars view.

I dated this sketch as 06-NOV-2012, but in truth I spent 3 nights to complete the whole sketch. Those nights were 03-NOV-2012 at 20:30, 05-NOV-2012 at 19:30 and finally 06-NOV-2012 at 23:00.   As there were a large number of stars and because the “sky movement”, every one of those nights I had to re-sketch by comparing previous stars positions and geometric figures (mostly triangles). Finally I compared my sketch with the image in Stellarium and I re-positioned some stars according to Stellarium.
In large sketches with a considerable amount of stars, while the sketch is being performed and the sky is in constant moving, the view changes constantly and the geometric figures used to spot the stars in the sketch, change too. In my first sketches I used Stellarium to evaluate the final product and if necessary re-position some stars (mostly the stars at the edge of the view).  But every time I sketch I think I am learning how to resolve the “moving” problem as my brain is also improving its ability in spatial location.

In adittion, this sketch was the first one I inverted and processed with photoshop. I published the initial result in the astronomy sketch of the day webpage: http://www.asod.info/?p=9829. Please compare the sketch published in the web page with the one published above.

Please enjoy this marvelous creation of God and good skies!!!

Blessings,
LG

Edited by Jennifer Steinberg (editor in chief)

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2 comments:

  1. Beautiful sketch, as usual! That book by H.A. Rey is amazing isn't it? He wrote and drew the entire book at his apartment in the middle of New York City... which is one of the most light polluted cities ever! So if he could see them... we should see them too! ;)

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  2. Wow I didn't know that about him. That is awesome. My city is about 9 million of people, therefore tons of LP. But is he could... this is an invitation to endure my stargazing activities!!!

    Thanks for visit my blog Jenn.

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