Observing Report 5/12/09 – 16/12/09

[barx1963 (Malcolm)]

Had a few good nights lately, have continued my project to get all the Caldwell objects visible in Vic. There are some well known objects in this report (Eta Car etc) but I will include them for the sake of completeness.
Malcolm
NGC 2516 (Caldwell 96)
Date 5/12/09 11pm Seeing - Very Good
Object is west and slightly south of approximately 24’ from Avior (Epsilon Carinae) and is visible to naked eye despite low position to south and light pollution. Epsilon Carinae is the westernmost star of the “False Cross” making it very easy to identify.
Sometimes mistaken as Lacaille’s Southern Pleiades which is actually IC 2602 to the south.
O’Meara makes some interesting points about the history of this object. Various sources quote different sizes for this object with a trend of smaller sizes being reported over time. Cluster appears very large in 24mm eyepiece with a 1.1deg field of view. There also appears to be 3 brighter stars on a gentle arc on north side. Uranometria doesn’t include these stars and shows a diameter of about 22”. The varying sizes arise as the visual cluster is quite large and includes the 3 stars, while accurate measurements by Hipparcos indicates that at least one of the 3 stars is not part of the cluster.
A very beautiful and rich cluster displaying a wide variation in colours and brightness. A most rewarding object.

IC 2391 (Caldwell 85)
Date 14/12/09 10-30pm Seeing - Good
About 2deg NNW of Delta Velorum centred on Omicron Velorum which is the brightest star in this cluster and is northern star in a line of 3 stars forming a very obtuse angle aligned approximately North/South. Next 2 brightest stars are a pair located approximately 30’ away to south east approximately 5.5mag. Many fainter stars in field.

NGC 2867 (Caldwell 90)
Date 5/12/09 11pm Seeing - Good
Located Iota Carinae (Southernmost tar in false cross also known as Aspidiske) . Moved approximately 20’ to north east to line of 3 very faint stars barely visible in finder which form an obtuse angle, then located fainter triangle moving in same direction. Moved north to line of 4 stars oriented east west. There are 2 stars close together on east side and one on west side. Remaining star has a “soft” glow. OIII filter doesn’t dim glow revealing object as a planetary nebula. Small with no obvious structure.

IC 2602 (Caldwell 102)
Date 14/12/09 11-20pm Seeing - Good
Located around Theta Carinae which is easternmost star of the “Diamond Cross” asterism in Carina. Cluster is visible to naked eye. Prominent members are 3 bright stars forming an angle with Theta Carinae in centre. 5 Fainter stars form a “five of diamonds “ shape to the south east. Many fainter stars in cluster. Also known as the Southern Pleiades.

NGC 2244 (Caldwell 50)
Date 14/12/09 11-30pm Seeing – Good
Found faint naked eye star 8 Monocerotos which is closest naked eye star in Monoceros to Bellatrix in Orion. Cluster is visible in finder to ESE of star. Open cluster of about 8/9 fairly bright stars arranged in a rough triangle. Many fainter stars also visible. Nebulosity associated with NGC 2377-8,46 (the Rosette Nebula) is not visible.

NGC 4755 (Caldwell 94)
Date 14/12/09 12-30pm Seeing - Good
The Jewellbox Cluster. Located se of Beta Crucis which forms the easternmost arm of Crux. 5 bright stars in triangle with bright ruby star in middle. Many (hundreds) fainter stars appear in background.

NGC 3766 (Caldwell 97)
Date 16/12/09 11-00pm Seeing - Fair
From NGC 3532 (naked eye cluster) located bright wide spaced double star O1 and O2 Centauri, then used finder to locate line of 5th mag stars oriented NW to SE about 2deg further south. Nebulous patch within this line is obvious in finder. Using 24mm eyepiece, there are 4 stars arranged in a “T” shape. The star at the foot of the “T” and at the junction are obviously red in colour. The foot star is mag 7.2 V910 Centauri. Many fainter stars, much colour variation.

Collinder 249 (Caldwell 100)
Date 16/12/09 11-30pm Seeing - Fair
From NGC 3766 located line of stars oriented roughly south east. Southernmost star is V810 Centauri which appears associated with a small cluster (St14) which looks like a mini Crux. Scanning west we find Lambda Centauri which appears orangeish. To south of this is a bright lineal open cluster. According to sources consulted, entire cluster is approx 1deg wide and encompass all stars visible within IC 2948 (Running Chicken nebula). Although centre of cluster is bright, most of it is very faint, which are revealed with moderate power eyepiece (24mm at 6.5x).

NGC 3372 (Caldwell 92)
Date 16/12/09 11-45pm Seeing - Fair
The Eta Carina nebula. Easily visible to naked eye as a bright nebula to east of False Cross. Large and bright with V shaped dark lane splitting it into 2 segments. Much structure is evident. Higher power (13mm at 115x) revealed bright orange star in cluster to have nebulous “wings” which is the Homonculous surrounding Eta Carinae. Dark patch next to Eta C. is the Keyhole nebula, shape is obvious.

[michaellxv (Michael)]

Fantastic report Malcolm, makes me want to go back outside and find them all but it's bedtime.

[ngcles]

Hi Malcolm,

Great report as usual -- thanks for posting it.

Particularly enjoyed your description of NGC 3766. I happened to spend quite a long time looking at it last month (gee, I wonder why??) with the 18". Besides the two most obviously orange, bright stars there are a lot of fainter stars that are creamy or buttery. It really is a wonderfully colourful cluster.

Same goes for NGC 2516. If it were in the northern hemisphere, we'd never hear the end of it. Down here, particularly in that part of the sky that is the richest patch of all, it's just another cluster. Stupendous object for 4-8" 'scopes.


Best,

Les D

[DavidU (Dave)]

I enjoyed reading this last night. Super report Mal.
Keep it up.

[Lismore Bloke (Paul)]

Another excellent report Malcolm, nicely written and with good detail. Well done.

[barx1963 (Malcolm)]

Thanks Michael, Les, David and Paul for your kind comments.

Les, 3766 is quite amazing, I wish I could have described it better, lots of subtle colour, I just couldn't find the words. And 2516, although I have seen it in small scopes, this was the first time in anything decent, definitely should be on every beginners list, one of the most stunning open clusters out there.

[Paddy (Patrick)]

Nice report Malcolm. You convey the beauty of the DSOs you've described very well. I am inspired to have a look at some of these that I haven't seen and to revisit the ones that I have.

[barx1963 (Malcolm)]

Thanks Paddy. There is lots to see around the False Cross at this time of year. I think a lot of us tend to look at Eta Car and forget about the open clusters that are all over this part of the sky. A nice OC is always worth seeing, and teasing out colour is just part of the attraction.

[pgc hunter]

Great report, very well structured and good descriptions. I too was surprised by NGC 3766 when I first saw it, I mean you never hear about in literature or even in observing reports and things like that, yet it kicks the butt of many Messier clusters!

I'm sure if it were in the northern hemisphere, it would be as famous as M57.

[barx1963 (Malcolm)]

Oops! Sorry all, just discovered an error in this report. I had reported IC 2391 (Caldwell 85) as IC 2516. My apologies. Often pays to double check notes!

PGC, thanks for your comments. i loved looking at NGC 3766, but I must say NGC 2516 was definately my favourite object object from these sessions.