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Old 09-01-2008, 02:01 PM
žAB
Its only a column of dust

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Obs Report 10/1/08 - double stars, PN's, Rosette Neb

Well, living in Melbourne, the spiritual home of "morning cloud" that arrives at 8pm and stay with us until 12 the next day, I dragged my 10" reflector out knowing the risks. Sure, it was clear at 9pm, but who knows. I found out the hard way a couple of nights ago. Well, it looked clear, and the forecast said "generally clear". By dusk I could see that Sirius was twinkling a fair bit, much more than the previous night. Indeed, the seeing was no where near as good, and actually seemed to deteriorate throughout the night as a slight wind picked up. Transparency however was pretty decent.

I downloaded info on some tight doubles in Canis Major to challenge myself with. The results are quite surprising! Being overhead, Canis Major is an ideal hunting ground for double star enthusiasts, such as myself.

The scope held its collimation even after being hauled in 'n' out twice and after being swung repeatedly across every tube orientation.

Time: 11.00pm-2.30am
Scope: 10" GSO dob
Seeing: 5/10
Transparency: 4/5
Temp: 15║C

BU 568
This is a tight double seperated by 0.8". Component A is mag 7.2 and B is 7.5. My 10" reflector could comfortably split it at 357x.

B 706
The 9th magnitude primary is a orange colour. The B component is mag 9.2. With a seperation of just 0.6", it is approaching the limit for a 10" scope. I could confirm a split at 357x, a hairline gap between the two airy disks! Seeing wasn't great so it took perseverance to actually spot the gap between the stars. The seeing caused a complete washout at higher powers. This is one I'll definately re-visit on a better night.

DON 181
Now this is really pushing it. The maximum theoretical resolution for an optically excellent 10" telescope is around 0.4" This double star pair is seperated by 0.5". Once again, seeing permitted a maximum useful mag of about 300-350x, no higher. The two components are both around mag 8.5. At 357x, I could detect distinct elongation, but the seeing was beginning to smear the star. This is one I'll save for excellent seeing conditions.

M1 Crab Nebula
At 96x it appeared as an oval haze, quite obvious. A filter improved the view. It appeared to have a brighter, almost rectangular area making up the central regions and oriented almost perpedicular to the fainter oval.

Eskimo Nebula
Showed the central star and a brighter oval central region at 250x with the narrowband filter, slightly flattened across one end. The Eskimo's 'parka' was plainly visible as a circular haze surrounding the central part of the nebula.

Rosette Nebula
Using 56x with the filter, I could trace a wide, faint ring around the cluster NGC 2244. The northwest side of the nebula appeared thicker and brighter than the rest.

NGC 3579
Stumbled upon this excellent nebula in Carina while hunting for the Running Chicken Nebula. At 56x I could see a bright comet shaped nebula with a broad fanned 'tail' streaming from the 'head' in a northerly direction. Increasing power to 96x made the nebula's figure more pronounced. Another, fainter section was visible just north of the bright comet-shaped nebulostity, with the two being seperated by a wide rift. This section featured a vague 'L' shape, with the long stem running east-west and bisected by a large dark void. Increasing power to 192x with the filter, I could spot another fainter nebulosity about 6' southeast of the main complex, near an adjacent 12th mag star. This feature showed distinct N-S elongation. This is an excellent nebula with my 10" showing considerable detail and I am sure it would be a well-known showpiece object if it were not overshadowed by the heavyweight Eta Carina nebula and the numerous clusters in this region.

NGC 3603
A nebula and open cluster complex located about 20' east of NGC 3579. At 96x, it can be seen in the same FOV as NGC3579. A ruddy 10th magnitude star dominates this complex and at 156x my 10" reflector resolved 6-7 faint members packed tightly around the star. The nebula appeared rougly oval with a slight E-W elongation. At 156x, 192x and 250x with the filter I observed a thick dark lane cutting across the nebula just south of the main star and oriented approx NE-SW. Using averted vision I could also detect a small notch at the SE end of the dark feature, giving it the appearance of a Ball-pein hammer. This is another interesting object that is rarely observed by amatuers.

GUM 39
Failing to spot this faint cloud previously under weak moonlight, I had another crack. Located about 40" WNW of Lambda Centauri it is easy to locate its position. Using 56x with the filter, I couldn't confirm a sighting. However, increasing the mag to 96x with the filter, i could just discern a brightening of the background sky, centered around a 9th magnitude star within the cloud. Jiggling the tube helped, and upon careful observation I could confirm a vague E-W orientation of the nebula.

NGC 3199
Another relatively unkown but wonderful nebula in Carina. Easily found about 2.5║ northwest of the Eta Carina complex. At 96x with the filter, my 10" showed a delicate, broad crescent shaped wisp with a brighter knot associated with two 11th magnitude stars at its eastern end. The nebula seemed to taper off in brightness as it progresses further west.

NGC 2867
Small planetary nebula located about a degree northeast of bright naked eye star Aspidiske. Distinctly non-stellar at low power despite its small 14" size but rather bright at mag 9.7. higher magnifications revealed a circular greyish blue disk not unlike Uranus. At 250x and 357x I thought i could hint at annularity but couldn't confirm. Will be interesting to revisit this at very high power under good seeing. This is a fine planetary for small telescopes but again it is rather unknown owing to it's far southern location and proximity to the southern sky's most brilliant objects.

IC 2501
Now this is one tiny PN! At 56x, it is stellar. Infact, it is stellar at all mags upto around 200x. Only at 250x did I see a tiny, tiny bluish disk. At 11.3 magnitude it is easily lost amongst the countless field stars. The angular diameter is given as a mere 2". The disk was more obvious at 357x but again still painfully tiny.

At this point it was around 2.30am and ofcourse the inevitable happened - that infamous, UNFORECASTED Melbourne clag moved in hastily to put an end to the fun. But atleast this time, even with less than good seeing, I was given a few hours which was well spent seeing objects which rather surprised me!
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Old 09-01-2008, 08:29 PM
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goober (Doug)
No obs, raising Harrison

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Quality stuff - the Rosette and associated cluster is on my list, but when I get out to a dark sky site. I'll note those deep south planetaries down as potential targets. Always wanted to go after the "blue" planetary near Crux.
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Old 19-01-2008, 03:47 PM
žAB
Its only a column of dust

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^^ the blue planetary is cool. It's like observing a larger version of Uranus. It's a perfect orb, uniform in surface brightness. A perfect celestial creation.
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Old 19-01-2008, 03:56 PM
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erick (Eric)
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I'm so short on PN observations - I only have a couple so far (well, there is so much else of interest in the sky that is easier to find ). I have gone searching for the blue PN a few times, without success. I'm going to have to get serious!
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