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Old 16-03-2008, 07:23 PM
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ngcles
The Observologist

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Sydney Observers -- Pup alert

Hi All,

Just a quick note to say that the seeing in Sydney tonight is very good.

I've just seen Sirius B near zenith for the 3rd or 4th time in my life using a 12" f/5 dobsonian newtonian at x428 -- seen with little difficulty. Splitting Nu Orionis was a doddle at only x140 and Saturn looks superb, despite its fairly low altitude at 8.20pm.

Get amongst it while you can, moonlight or no! Imagers take note!

Best,

Les D
Contributing Editor
AS&T

N.B for Nu Orionis, read "Eta Orionis" instead -- see below

Last edited by ngcles; 16-03-2008 at 10:43 PM. Reason: Error
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  #2  
Old 16-03-2008, 10:20 PM
Karlsson
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Les,

No luck in this part of town, mate (Hornsby way)... seeing was 5/10 at best, vapour and thin cloud everywhere - naked eye mag perhaps 4.6 or so (usually 5.5)

So I packed and dried up...

Never realised nu Ori was a double... any idea what the WDS number is?
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  #3  
Old 16-03-2008, 10:41 PM
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ngcles
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Hi Karlsson & All,

Doh! I had a "seniors moment". Not Nu -- I meant to type Eta Orionis.

Of Eta at least, this SIMBAD query page lists all the identifiers.

http://simbad3.u-strasbg.fr/sim-id.p...&Ident=HR+1788

I tend to use Eta at this time of year as a seeing test as it is just under 1.5" separation.

Best,

Les D
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  #4  
Old 16-03-2008, 11:19 PM
ausastronomer (John Bambury)
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The PUP, the MOON and SATURN and everything coming together

Quote:
Originally Posted by ngcles View Post
Hi All,

Just a quick note to say that the seeing in Sydney tonight is very good.

I've just seen Sirius B near zenith for the 3rd or 4th time in my life using a 12" f/5 dobsonian newtonian at x428 -- seen with little difficulty. Splitting Nu Orionis was a doddle at only x140 and Saturn looks superb, despite its fairly low altitude at 8.20pm.

Get amongst it while you can, moonlight or no! Imagers take note!

Best,

Les D
Contributing Editor
AS&T
Hi Les,

Seeing here last night was pretty reasonable. I spent my time on the Moon and Saturn with some great views. Never thought to try the PUP last night, although I tried unsuccessfully once recently at Coonabarabran under marginal seeing conditions.

Living right on the Southern side of Tuggerah Lakes (50 metres) I usually get very good seeing at Zenith and to the North looking across the lake with over 10km of water underneath my line of sight.

Tonight the seeing was better than last night (9/10) so I figured to give the PUP a try. It was pretty easy in the 18"/F4.5 at 420X (5mm Pentax XW), notwithstanding it was right beside the diffraction spike. I then swung to the moon and got some excellent views at 525X (10mm Pentax XW in 2.5X Powermate). I was able to see 8 Craterlets in the floor of Plato with another that I know of just North of the East Wall Pit hidden in shadow and not visible at this moon phase. The Rille down the middle of the Alpine Valley was also very prominent. I then went to Gamma Centauri and was able to split it at 525X. I then went to Saturn and got one of the best views I have ever had of it. I was still at 525X as the scope powered over to it and I expected the view to be pretty mushy, it was sharp as. I spent quite a bit of time on it at 525X. What is observable of Cassini Division due to the ring plane inclination, was easily visible like it had been sliced through with a router. Clear black space. The crepe ring was easily visible as was the Encke Minima. Surface banding and detail on the planets' disk was stunning. I figured, "this might cop a bit more". I removed the 10mm Pentax XW and stuck the 8.5mm Pentax XF into the powermate for 620X. The view held up beautifully, this time with Encke Division popping in and out just where the rings appear most face on. I then decided to try more power. I put the 7mm Pentax XW into the focuser for 750X. The view was still very nice in moments of steadiness but just starting to fade in and out a bit. Still an outstanding view. All the detail that was visible at 620X was still there when the air was still. I then decided to go all out. I stuck the 5mm Pentax XW into the Powermate for 1050X. It held up pretty well but just dropped out a little too frequently and servocat was struggling to keep the target in the FOV. However it was still a very nice view and in no way "mushy".

One of the best nights of high power observations I have ever had and ever likely to have. Easily the best views I have ever had of Saturn. It is good when everything comes together and all falls into place at the same time. Excellent seeing, good optics, and last but not least a well cooled and collimated telescope. Unfortunately I have to work tomorrow otherwise I would have stayed out longer, much longer .

Cheers,
John B
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Old 16-03-2008, 11:35 PM
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erick (Eric)
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Wowee John! Salivating at the keyboard here! Glad you had a special few hours!
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Old 17-03-2008, 12:38 AM
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ngcles
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Puppy love

Hi John & All,

Seems like you had a terrific session too John.

John wrote:

"Tonight the seeing was better than last night (9/10) so I figured to give the PUP a try."

I didn't have a 'scope out last night (played with my guitar instead). I would have given it an 8, but we are more than two hours drive apart. Still, in the scale of things, an 8 is only seen about 1/30 nights on my reckoning. I think I've only ever rated the seeing 9/10 on maybe 1/2 dozen-odd occasions in the last 16-17 years I've kept a log consistently. Never seen a 10/10. The transparency wasn't much chop and I think there will be a fairly heavy dew in the morning with all the moisture in the air.

John wrote:

"I was able to see 8 Craterlets in the floor of Plato with another that I know of just North of the East Wall Pit hidden in shadow and not visible at this moon phase. The Rille down the middle of the Alpine Valley was also very prominent."


Yes, I must admit (at the risk of getting kicked out of the deep-sky fanatics guild) I looked in on the Moon too and it was showing impressive detail. I only went to x214 but did see 3 craterlets in Plato (the double and the single nearer centre) (these are C&D + A -- I think). The one you are refering to North of the pit is "F" -- and I've never seen it (but I don't often look at the Moon). The rille in the Alpine Valley was, as you note quite prominent. Straight Wall (Rupes Recta) in Mare Nubium was also nice and I also noted the craters Birt A & B nearby and the Rima Birt Rille.

John wrote:

"What is observable of Cassini Division due to the ring plane inclination, was easily visible like it had been sliced through with a router. Clear black space. The crepe ring was easily visible as was the Encke Minima. Surface banding and detail on the planets' disk was stunning. I figured, "this might cop a bit more". I removed the 10mm Pentax XW and stuck the 8.5mm Pentax XF into the powermate for 620X. The view held up beautifully, this time with Encke Division popping in and out just where the rings appear most face on."

Yowser!! With the 12", I went to x313 on Saturn and it was a stable image most of the time. Cassini was easy at the far extensions of the rings and I also noted the Enke _minima_ (but not the Enke division per se). I saw 6 moons but didn't go through the exercise of identifying them (except Titan -- that's too easy). The Crepe ring was easy to see and though it was basically brownish, I also picked up violet hints in it that can be seen when the rings are getting close to being edge-on. At this point (about 10pm), it crossed my mind to get my 18" out, but considering 1/2 hr to assemble + collimate + etc + cooldown, I let it go ...

Eta Orionis was a ridiculously easy split at only x140 and 1.4" -- you could have driven a bus between the space (well, alright a Coaster bus). I think probably 0.7", or perhaps just slightly better at higher magnifications for an exactly even pair might have been possible tonight with 12".

John wrote:

"Unfortunately I have to work tomorrow otherwise I would have stayed out longer, much longer "

You and me both.

Great report, much enjoyed -- glad you saw the pup too. Isn't the Argo/Servocat combo just fantastic!

Best,

Les D
Contributing Editor
AS&T
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  #7  
Old 17-03-2008, 07:46 AM
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goober (Doug)
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I have been splitting Eta Orionis (and Alnitak, which seems to have a similar separation) easily all summer - needs reasonable seeing and ~154x and above for my 4" apo.

Sounds like great conditions in and around Sydney.
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  #8  
Old 19-03-2008, 01:42 PM
žAB
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If you want a challenge, go for 52 Orionis. Easily found SW of Betelguese, this pair is seperated by 1.1".

Yeah Sydney''s getting the goods lately, here in Melbourne its been very unsettled lately. Damn those inversions and 30 degrees at 2am desert winds!
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