|NGC 6962 & Co.: Galaxy Cluster (Aquarius) RA: 20h 47.4m / DEC: +00° 24'.2|
Instrument: 18-inch Obsession
Galaxy clusters are among my favorite deep-sky targets. And the six stellar gothams at left encompass many of the qualities that draw me to these fascinating objects. First, the very notion that we can point a telescope at the night sky and scoop up handfulls of star cities; each representing the combined mass of more than one hundred billion suns, is just mind-blowing to me. Then, to have these unimaginably large objects appear so fragile, just adds to the mystery.
As I mentioned, six galaxies appear in the sketch at left which was made at 199X in the 18-inch Obsession. These include NGC 6969, NGC 6961, NGC 6962, NGC 6964, NGC 6965 and NGC 6967. The largest and brightest of the sextet is NGC 6962. Its 2' by 1'.5 oval form is south of center near a trio of 11th magnitude stars. The 12.1 magnitude barred spiral features a faint stellaring at the core and the long axis of the oval is aligned roughly east to west. About 2' southeast of NGC 6962, 13.0 magnitude NGC 6964 emerges from the charcoal sky, a 30" by 15" hyphen with a 13th magnitude GSC star marking the southeast tip. In the opposite direction, some 3' northwest of NGC 6962, the delicate elongated glow of NGC 6961 is seen. This 30" by 20" fog patch has a blue (B) magnitude of 14.7, suggesting a visual (V) magnitude of 13.7 or thereabouts.
The fourth galaxy in the field is NGC 6959. This transitional galaxy has a similar published magnitude to NGC 6961--4' to the south--but is more obvious at the eyepiece of the big Dob. Its 60" by 30" form is aligned east-northeast to west-southwest and is framed to the southwest by an interesting collection of four stars. Three of the four are arranged east to west; two 13th magnitude stars with a mid-14th magnitude ember between. The fourth is a mid-12th magnitude spark about 1'.5 west of the galaxy. Moving 7' east from NGC 6959, a sliver of light known as NGC 6967 pops into view. A 10.8 magnitude star marks the eastern extent of this 13.1 magnitude edge-on spiral. A noticeably brighter core is hidden within the general 60" by 15" haze.
And that leaves faint, subtle NGC 6965 for last. That's appropriate since this was also the last galaxy of the group to emerge when I made the observation. It's stationed in the northeast quadrant of my sketch, forming the apex of an isosceles triangle along with NGC 6967 and NGC 6961. Having a visual magnitude of 14.1 and appearing 30" in diameter, this delicate gauzy glow still represents the combined output of nearly one hundred billions suns. It is best seen with averted vision and careful attention, as are many of the approximately 50 stars dotting the field in my rendering.
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Revised: September 6, 2005 [WDF]