Strangways sky report 6/11/09

[Paddy]

Here is my observation report for 6/11/09. I was not planning to do a report, but just go grazing. Then I thought about how much more I see and learn if I go through this process, so I got out the dictaphone.

Here 'tis...

Observation report 6-10-2009

Telescope 400mm f4.9 tri-dob relfector
Eyepieces 28mm UWAN, 17,13,9 mm Naglers, Paracorr
Transparency 7 Seeing 2
No moon during observing session.

The plan: Work through Burnham’s Celestial Handbook (on long loan from a friend) for Pavo, Cetus, Pisces Austrinus and Reticulum, focusing on Galaxies.

The best laid plans…

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

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.

NGC 6810 GX in Pavo 175x looks like an edge on spiral, no sign of spiral arms, sense of an elongated nucleus. I estimate its about 2-3’ long.

NGC 1055 GX in Cetus 175x Edge on spiral, not a distinct nucleus, but bright in the middle. I have an impression of graininess suggesting some dust lanes as if it’s not quite edge on. I estimate its length at 4’

M77 GX in Cetus 175x Bright, round, very concentrated at nucleus. Slightly elongated. Star to the East. No spiral structure, I have an impression of a dark band the bright nucleus and halo beyond this.

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.

NGC 955 GX in Cetus 175 Small edge-on spiral, quite distinct but overall not very bright. Two bright little foreground stars adjacent. Lies in a straight line with NGC 936 & 941

The night is late, the moon is close to rising, so it’s time to go for some brighter galaxies.

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’

NGC 1332 GX in Eridanus 175x Edge on spiral with bright smudge to the East – appears almost a continuation of the plane of the main galaxy. I am unsure if these are interacting galaxies or whether it is all one galaxy with dust lanes obscuring the connection. (checking reveals that they are a pair, NGC 1331 being the smaller galaxy). I estimate that the pair take up about 7’, NGC 1332 is about 2’ long.

NGC 1532/31 175x My favourite pair of interacting galaxies, with NGC 1531 plunging it to the centre of edge-on spiral 1532. NGC 1532 has bright nucleus and visible dust lanes, seems to be brighter on Western side of nucleus. Darkening quite distinct along edge of 1532 especially on western side of nucleus. The other side appears more uniform, but fainter.

And then the moon rises, so I set, well pleased.

[pgc hunter]

great report! You galaxy observations continue to impress me...must be that combo of aperture and dark skies :)
NGC 6572 is an impressive cluster, I've noticed it's member stars are exceptionally bright compared to other GC's.Your description of NGC 1300 is most impressive....all I get is the core. Time to leave the city I think!

Keep 'em coming mate.

[Lismore Bloke]

Excellent report Patrick. Like PGC, I am much impressed by the detail you are seeing. The dictaphone certainly seems to have played its part in helping you to see and remember more. Which dictaphone did you end up getting, if you don't mind my asking? Cheers, Paul.

[DavidU]

Great report Patrick, it makes me want to take the 12" to a dark site.
But alas it won't fit in my car !

[Paddy]

Thanks again for your encouraging feedback, gentlemen! The dark skies are a definite bonus - I don't reckon I could live in light polluted skies again. I'm looking forward to the Little Desert and VicSouth next weekend, in spite of stinking heat.

Paul, it's a Sanyo M1110C walkman style thing. It uses an ordinary cassette and has voice activated recording. I've actually had it for years and forgotten it until the recent thread in which Les and others talked about a dictaphone. Only thing with the voice activation is that I have to remember to start talking a bit before I say anything that I want recorded, otherwise the first bit gets lost as it starts up, so I get "....laxy in Cetus". Reminds me of the voice announcements that they had at Central station in the 1980s "the next train goes to mu plains" having cut off the e. Anyway, I just have to remember to say "starting up again" before I get down to business.

[Rob_K]

Great report Patrick, glad to see you getting the most out of this scope! :thumbsup:

Cheers -

[ngcles]

Hi Pat & All,



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.



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.




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_search?v=poss2ukstu_blue&r=02+27+37.34&d=-01+09+23.3&e=J2000&h=20.0&w=20.0&f=gif&c=none&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.



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

[Paddy]

Thanks so much, Les, for your detailed response to my report. I find your posts are such great value, not only explaining a lot of what of I've seen, but prompting me to go back and look more deeply. I've been boning up on the classification of galaxies - at first glance it seems simple, but I'm getting more of a sense of its subtlety and the challenge of using it at the eyepiece.

All great grist for the mill!