Object of the Week August 12, 2012 – NGC 6822 with Ha Regions
Barred Irregular Galaxy
Sagittarius
RA 19 44 56.5 DEC -14 48 11
Size: 15.6' x 13.5' Mag: 9.3 (B) (MegaStar – RC3)
Deep Photo on Adventures In Space: http://astronomy-mall.com/Adventures...ce/barnard.htm
Nicely placed this new moon we find Barnard's Galaxy, NGC6822. This faint barred irregular galaxy in Sagittarius is a low surface brightness galaxy of a fair size that is viewable with both small an large scopes. Ngc6822 holds significance in astronomy for one reason due to Edwin Hubble's detection of 11 Cepheid variable stars in this galaxy which are used to accurately determine distance.
A fun project was to track down several of the Ha regions in this object in my 18" f/3.7 StarMaster. Here are two observations of mine on Ngc6822 in the 18" where the first one was from last year with the intent of tracking down 4 of the Ha regions and the other observation I only knew of the two brighter Ha regions. As recently as last night I have detected the glow of this galaxy in a 5" refractor from a 20.7 Sqm site. Deep photographs show even more Ha regions as more challanges.
8-27-2012 22:05 PST from a site well south-east of the bay area, CA. South is 'down' in my view.
NELM better than 6.6 with SQM 21.55 where I rated seeing as excellent and transparency very good (8/10)
NGC 6822 IC 4895 MCG -2-50-6 19 44 56.5 -14 48 11
Using 9mmNag, 216x with ParaCorr total sizes of 7/10fov [16'] x 4/10 fov [9'] Unfiltered shows the two northern H2 regions. The H2 region to lower left [W] of the other is brightest of the two unfiltered and both appear to bracket the glow one on either side of the north end of the glow in EW orientation to each other. 5mmNag 389x shows EW elongation of the brighter H2 region west of the other one. Looking for the very dim H2 regions we move co-linear west of the two H2 regions by their spacing to a field star. Now move 1/2 of this length to see the H2 regions. These are very dark targets that only present themselves in strained averted over 50% of the time that are closely spaced.
Another measurement without the Ha regions was interesting perhaps as well:
10-10-10 from same site but in lesser skies with seeing 8/10 but transparency 6/10
NGC 6822 IC 4895 MCG -2-50-6 19 44 56.5 -14 48 11
Using 9mmNag, 216x with ParaCorr Extends 3/4 x 1/2 fov [17x11'] up and to right [NS] Stands out well on East edge in 16mm. Appears as NS elongated shape. NPB filter we see the two knots appearing 6/10 of a field down and to left [N] from the bright field star at S end of the galaxy glow. The second knot is 1/5fov [4.5'] East of the 1st. both are similar brightness and maybe 1/80 fov [0.3'] in size. In unfiltered view all the glow appears as just that, a glow with no distinctly brighter glow. OIII filter was swapped in and I felt it offered a bit better contrast on the knots.
What do you see?
"GIVE IT A GO AND LET US KNOW"
GOOD LUCK AND GREAT VIEWING!
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