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Old 09-11-2009, 11:14 PM
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ngcles
The Observologist

ngcles is offline
 
Join Date: Dec 2006
Location: Billimari, NSW Central West
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Hi Pat & All,

Quote:
Originally Posted by Paddy View Post
NGC 6752 GC in Pavo, 132x I start with a GC whilst my eyes adapt to the dark. I note a small definite core with strands of stars distracted from the cluster. To the East, 2 long curved strands enclose a relatively star free field, giving the impression of a pair of pincers. I am curious about how these do not seem to show up on images of the cluster. To the SE is a bright star with a tendril of stars reaching out to it. Other strands of stars reach out to the SW, W & NW. I estimate the size of the cluster as about 20’. Quite a number of resolved stars in front of background haze. I note a small L shape in the core. On the side of the core opposite the “pincers” I note a sausage shaped asterism close to the core
A really good observation to start with. From memory, NGC 6752 has the 2nd brightest brightest individual member stars of any GC visible here from Earth (after M4). John Herschel originally came up with the idea that it was two clusters superimposed on each other and observed "The bright part at the centre is occasioned by a group of stars of some considerable magnitude when compared with those of the nebula. I am inclined to think that this may be two clusters in the same line; the bright part is a little south of the centre of the large nebula". I reckon it resolves more easily than any other GC in the sky. There has always been for me a strong impression of two seperate layers of resolved stars.

Quote:
Originally Posted by Paddy View Post
NGC 6769/70/71 GX in Pavo. 175x Very faint group of galaxies. At first the galaxies appear more like the many patches of nebulosity seen around the Magellanic clouds than galaxies. With averted vision, its possible to make out a pair of galaxies, one a barred spiral, appearing clockwise rotation in the eyepiece. The other is a face on spiral with distinct nucleus and a little hook shape of foreground stars on one edge. Between these two is a bright foreground star.
I covered this little group as part of a deep sky delights article a couple of years back (Sept/Oct 2007). Here are my impressions of the group plus IC 4845 & IC 4842 with 46cm in 2006:

NGC 6769
RA: 19h 18m 23.0s Dec: -60° 30' 00"
Mag: 12.6 (B) S.B.: 13.0 B-V: +0.80
Size: 2.3'x1.4' Class: SAB(r)b pec P.A.: 123
Inclination: --- R.V.: +3863 Source: RC3 *


NGC 6770 Multi-Galaxy Sys *
RA: 19h 18m 37.0s Dec: -60° 29' 47"
Mag: 12.8 (B) S.B.: 12.9 B-V: +0.89
Size: 2.8'x1.9' Class: SAB(rs)b pec P.A.: 31
Inclination: --- R.V.: +3883 Source: RC3 *


NGC 6771 Multi-Galaxy Sys *
RA: 19h 18m 39.9s Dec: -60° 32' 47"
Mag: 13.6 (B) S.B.: 12.5 B-V: +1.05
Size: 2.3'x0.5' Class: SB(r)0+? sp
P.A.: 120 Inclination: --- R.V.: +4223

IC 4842 Galaxy *
RA: 19h 19m 24.5s Dec: -60° 38' 39"
Mag: 13.4 (P) S.B.: --- B-V: ---
Size: 1.9'x0.9' Class: E: P.A.: 20
Inclination: --- R.V.: +4118 Source: RC3 *

IC 4845 Galaxy *
RA: 19h 20m 22.8s Dec: -60° 23' 25"
Mag: 12.3 (B) S.B.: 10.9 B-V: +0.77
Size: 1.8'x1.5' Class: SA(rs)b: P.A.: 82
Inclination: --- R.V.: +3893 Source: RC3 *

-69 and -70 are a close pair of egs with a few faint stars superimposed. The field is moderately rich in faint *s. The brightest is probably -69 in PA 135, roundish oval shape 1.5' x 50" rises to the centre slightly in brightness. -70 is immediately to the W with the halos almost touching. -70 is more round, about 1' diameter with a weak azonal brightening to the centre without apparent nucleus or core, but has reasonable SB.

-71 is to the SE by a few arc-mins and is a small 1.5' x 20" spindle in PA 135 -- pointing NW to -69. It is comparable in SB to -69. Brightens slightly to the axis and centre with no apparent nucleus.

Further SE by about 8' is IC 4842 wcih is a lower SB eg that the three preceeding objects. Amorphus blob 1.5' diameter possible slight elong in PA 0 with a weak central brightening and no other structure apparent.

IC 4845 is NE of the -69 & -70 pair is IC 4845 by 15'. Roughly round, slightly oval in PA 90 with a mag 13* on the edge of the halo nearest the pair -69 & -70. Not shown on Megastar or RealSky. 1.25' x 1' with a weak central brightening. and no zones or nucleus.

A really nice little group.


Quote:
Originally Posted by Paddy View Post
NGC 936/941 GX in Cetus 132x Both galaxies appear in same field. Both appear to be face on spirals, NGC 936 much brighter with bright nucleus. Although it is listed as a barred spiral, I cannot discern the bar. NGC 941 much fainter, oval shaped. mag 175x the galaxies appear about 14’ apart centre to centre (half a field of view) A little more detail apparent at higher mag.
A nice pair eh? NGC 936 is an interesting galaxy. It is classified as SB(rs)0+ implying a barred lenticular galaxy with evidence with some ring-structure features. To me (looking at the DSS) it looks like a barred "shell" galaxy. There seems to be a lot of concentric weak rings (shells) in the outer halo and has a very intense and large nucleus surrounded by an almost complete bright ring -- like for example M95. See a UKS (2) blue plate here:

http://stdatu.stsci.edu/cgi-bin/dss_...e&fov=NONE&v3=

It could also justifiably be classified SB(r)a -- ie a normal barred spiral with large bright bulge, tightly wound smooth arms and ring structures. Just on appearances (and that's how professionals classify galaxies too), it looks more like a barred spiral than a barred lenticular. Must say I've never seen -41 -- it has been on the to-do list for 3 years.

Quote:
Originally Posted by Paddy View Post
NGC 1300 GX in Eridanus. 175x Beautiful barred spiral, dark lanes between the spiral arms quite obvious and very distinct nucleus. I estimate size as 7x3’
T'is indeed. A personal favourite of mine but doesn't show arms until you get to 40cm. A really stunning object for 50cm+. Love it love it love it!

A great report mate. Hoping to get some dark-time myself next weekend.


Best,

Les D

Last edited by ngcles; 09-11-2009 at 11:46 PM.
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