Star associations in Barnard's Galaxy

[Ivan Maly]

Notes from the observation of Barnard’s Galaxy last night. Identifications are according to the Hodge Atlas of the Local Group. “H” are Hubble HII regions and “A” are Hodge star associations. “/” means spatial coincidence or close proximity.

16”. SQM 21.5. At 45x (Pentax XW40) Barnard’s Galaxy NGC 6822 is extremely large and sharply elongated. At 225x with the 8 mm Ethos the galaxy is hardly noticeable, but complexes HV/A8 and HX/A13 are immediately noticeable and completely nonstellar (~1’ each) next to two comparatively bright field stars that form the narrow S base of an equilateral triangle with a bright star on the N apex, as marked on DSS chart. A8 has a stellar core but otherwise little concentration and is the brighter; A13 has little concentration and is elongated EW. There is an indistinct glow in the position of HI/HIII. OIII filter does not enhance any of these 3 knots, although HV and HX look fine on the black background with the filter.

[Marko]

Barnard's Galaxy is large to be sure. My most careful study of it was in an 18" but I should re-visit as my skills and eyepieces are better now so I can be more clear on just what I detected in the area of H I and H III. I suspect from what I have been told that I did not see the H2 but rather saw the stars in them so I have retracted the claim in this report.
I give the report below as it is suitable for this discussion even with 'verification' required and that seems a nice project to revisit this month if I get some skies. I want to look for some of the other areas as well in any event.

NGC 6822 Type: Glxy Position: 19 44 56.5 -14 48 11 Con: Sgr
Date: 08/27/11 Time: 22:05 Site: WSprDSR
Scope: 18SmF3.7Pc Eyepiece: 9mmNag Power: 216
NELM: 6.6 SQM: 21.55 Seeing: 5 Transparency: 1.5
Description: 'BarnardsGalaxy: 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 50Pct of the time
that are closely spaced. Both Kevin and MarkW saw these as well.

[Ivan Maly]

I am looking at the fairly high-resolution color image

http://upload.wikimedia.org/wikipedi...27s_Galaxy.jpg

and although the field is rich, Milky Way stars, if any, superimposed on HI an HIII seems to be outshone by what seems to be OB giants in the stellar associations coincident with these regions (they are, conveniently, Hodge's A1 and A3). There is almost certainly a brightish Milky Way star on the NE edge of HIII (not coincident with the small A3 deep inside this region), but this star may actually be the only Milky Way star there.

In sum, I too would like to return to this area and observe it more deliberately - in truth, this time I did not pursue HI/A1 or HIII/A3 in earnest. I felt satisfied with finally seeing HV/A8 and HX/A13. I attempted them with 7" three years back more than once and failed, probably not because of an insufficient aperture but because of insufficient preparation.

[Howard B]

My latest observation of Barnard's Galaxy was at the 2008 Oregon Star Party. My notes read:

"Barnard's Galaxy is large, diffuse and indistinct but it revealed a good deal of structure and four HII regions. Barnard's Galaxy itself is a big, curved swath of galactic dimness that's punctuated with several handfuls of foreground stars and the two brightest HII regions at its northern end. NGC 6818 is nearby and shows a bright, well-defined round disc that's slightly darker in its center. The planetary is much brighter than Barnard's Galaxy or any of its HII regions. By the way, the OIII filter highlighted the two brightest HII regions only. 253x and 467x."

N6822_BarnardsGalaxy_N6818_crop.jpg N6822_BarnardsGalaxy_N6818_cropInvert.jpg

I've looked at Barnard's Galaxy several times since then and have found that it takes an exceptionally transparent sky to see anything at all - for instance, at the GSSP this past July I was barely able to detect its presence as a slight brightening and the sky was pretty decent at the time.

[Ivan Maly]

Interesting sketch of the galaxy and planetary together, and the information regarding the effect of the filter. I too observed NGC 6818 on the same night, for the first time with a large aperture. I too saw it as round, and looking like a very hazy donut.

[Steve Gottlieb]

For those who are want to pursue Barnard's Galaxy, more info on the HII regions and OB associations is at http://www.astronomy-mall.com/Advent...ce/barnard.htm and Hodge's 1977 paper is here

Another challenging target within Barnard's Galaxy is [Hubble25] VII, the oldest and brightest (16th mag) globular in the galaxy. In excellent conditions and high power it's non-stellar, though a detailed photograph is necessary to try and track down.

[Marko]

Last new moon I did as careful a study of Ngc6822 as I have ever done and armed with my 4.5, 6, and 8mm Delos on a great night from 21.6 skies with good seeing. Here is what I ended up with although this is rather verbose. My main goal was to revisit H1 and H3 and confirm I was only seeing the stars in them and not the glow in my 18" f/3.7. I have done that and can lay that one to rest. Need a bigger scope or better eyes.
I put notes seen on DSS in square brackets and other text is what I transcribed from field recording.

con: Sgr cmt: BarnardsGalaxy
NGC 6822 IC 4895 MCG -2-50-6 DDO 209 IRAS 19421-1455 PGC 63616
Glxy 9.3b 15.6x13.5' 5 IB(s)m RC3 19 44 56.5 -14 48 11
9:45pm 8mmDe 280x Looking at H5 in NW and H10 to the NE where H5 is brighter of the two. I will call the spacing between H5 and H10 as one unit distance [it is 3.3' on dss] If we move from H5 through H10 and go same distance [3.3'] East again we hit a tight double stellar object [Found this to be Gsc 5736:338 pair at mag 15.1]. We also see a dim diffuse glow that is 2/5 of the way from H5 to H10 [this is GSC5736:680]. An attempt to note the glow around H1 and H3 or Mcg 2-05-02 and Mcg 2-05-03 respectively did see very faint glow in those areas but not enough to make me feel the H2 area was spoted. I am thinking I saw just the star groups in each place and only with careful study as they are at limits of detection. If we move 1/3 unit distance [1'] east of H5 then move south we hit the very bright dot [GSC 5736:680] just south of this point then at 3/4 unit distance [2.5'] we hit EW positioned tight double where leading [GSC 5736:36] star is slightly dimmer than trailing star [GSC 5736:64]. If we from center point of H5/H10 we move two spaces south [6.6'] here we see a dim brightness and several very dim stars in this area of the galaxy. One of these stars is to the west of the bright region [Think this is at 19 44 56 -14 49 00]. Another visible stellar presense with 4.5mmDe, 376x, is NW of H10 by 1/5 of unit space [0.65']. Another one is due south by same distance from H10. There are numerous other stars of this magnitude in the area of the galaxy. There is a 'box' of half unit spacing [1.6'] sides midway along the galaxy length and off to the East we spot the glow earlier noted with star to it's west as colinear with the most southern edge which is a bit longer [2' from GSC 5736:112 to :192] of this box and 1.5 times this side's spacing west [3' West of GSC 5736:192]. Also from the glowing area we head SW 1/10 fov [1.2' in 4.5mm] and see 3 or so stars in a line off in that direction of SW. [This line has GSC 5736:638 and :830 in it].