Mersing Apr 21 st

kochu · Post by **kochu** » Wed Apr 25, 2007 11:08 pm

Mersing Sky was good on 21 st Apr till clouds started rolling in at about 0100 hrs. Richard (Low) and me returned at 0330. ACC and Canopus Lim also were there and a lot of TASOS members. I just managed two pics. Sombrero and M51

http://www.singastro.org/album_showpage.php?pic_id=744

http://www.singastro.org/album_showpage.php?pic_id=743

Kochu/25-4-07

Canopus Lim · Post by **Canopus Lim** » Wed Apr 25, 2007 11:28 pm

Nice image.

Anyway, when you guys left at 3plus, the clouds cleared at 4plus. The sky (the whole sky) was nice! The Milky Way was clearly visible and structure easily seen. I saw about 4 meteors after you guys left but the meteors did not seem to originate from the Lyrids. However, being tired and beaten by so many mosquitoes (still having about 15 mosquito bites), I decided to go home after touring the Milky Way with my binos. It was nice especially the M objects were bright in the bino and it was 'star filled'.

Post by **acc** » Wed Apr 25, 2007 11:49 pm

It was indeed a great night at Mersing. Love the whirlpool galaxy. Heh I dont remember much about what happened after 2 am :oops: :oops:

kochu · Post by **kochu** » Thu Apr 26, 2007 9:31 am

Canopus Lim wrote:Nice image.

Anyway, when you guys left at 3plus, the clouds cleared at 4plus. The sky (the whole sky) was nice! .

Hi Canopus,

Nice to know you could enjoy a second session.

Strange are the ways of weather.
On our way back before Mersing town it drizzled for a while and we thought it was a wise decision to pack up our scope .

The views through Richard's and your scopes were awsome.

Kochu/26-4-07
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rlow · Post by **rlow** » Thu Apr 26, 2007 3:07 pm

Yes, we enjoyed great views thru both the 11" Astrosky and 12.5" Obsession, and we shared the views with some of the Tasos folks. Views thru both scopes were almost identical on bright DSOs, though there are very subtle differences in light throughput and resolution, discernable to the trained eyes. Some of the best views were of the distinct spiral arms of M51 Whirlpool galaxy, the myraids of tiny stars resolved to the core in Omega Centauri, the dark lane of Centaurus A galaxy split into two by a thin sliver of light, and the Homunculus nebulae looking much like the hourglass-like profile in the Hubble image AND with pink and green colour! A very fruitful trip indeed!

Canopus Lim · Post by **Canopus Lim** » Thu Apr 26, 2007 4:03 pm

The 11" Astrosky images are nice. A great 'steal'. Do bring it out more often.

For bright objects I think the difference between 11" and 12.5" is slight; I noticed slightly more stars resolved for Omega. It will be more apparent for dim objects near to the limit of detection. I think even for bigger scopes, since it requires a 20" scope to have dramatic improvement than a 12.5" scope in image brightness of stars, the difference for bright objects will be slight as a bright object being already bright will not show it more significantly. However, for dim objects (like galaxies) in which the scope is having problems seeing, the larger aperture will show it better in a more obvious way as one can see it without difficulty if at the right magnification/exit pupil; or show a bit more details.

The exit pupil determines the image brightness and hence if a smaller scope compared to a bigger scope at the same magnification, the bigger scope will always have a brighter image with brighter background as the exit pupil will always be larger at the same magnification; unless the larger scope is really bad. However, if compared at the same exit pupil, it is all square for both scopes and how much 'brightness/contrast' of the object actually depends on the telescope and eyepiece contrast; with the edge given to a bigger scope since at the same exit pupil it operates at a higher magnification (able to see more dim stars or more details due to the larger size of the galaxy/neb). Therefore the biggest benefit of bigger scopes is to operate at higher magnification (smaller exit pupil) and this way more details can be seen. At low magnification, there is not much difference between a larger scope and a smaller scope apart for brighter stars but extended objects roughly the same. Galaxies seem to work best on my scope between 2.2mm (140x) and 1.4mm (220x) exit pupil using my 11 and 7mm Naglers. I am happy that with this 2 eyepiece combination does give good results on galaxies and being parfocal to each other is a plus. I sort of like observing galaxies at Mersing since there is almost no chance in Spore due to the LP.

Post by **acc** » Thu Apr 26, 2007 5:12 pm

rlow wrote:the dark lane of Centaurus A galaxy split into two by a thin sliver of light,

I like to think of it as a Whopper burger: luminous clouds of seasame bun halves that sandwich two thick & dark beef patties, with a sliver of lettuce peeking out from between them.

Yummy.

Canopus Lim · Post by **Canopus Lim** » Thu Apr 26, 2007 5:32 pm

"I like to think of it as a Whopper burger: luminous clouds of seasame bun halves that sandwich two thick & dark beef patties, with a sliver of lettuce peeking out from between them. Yummy. "

Yup it looked better than last month's burger for sure.

If only that was In-And-Out burger...

rlow · Post by **rlow** » Thu Apr 26, 2007 9:01 pm

For bright objects I think the difference between 11" and 12.5" is slight; I noticed slightly more stars resolved for Omega. It will be more apparent for dim objects near to the limit of detection.

I concur with that; thats why we are anticipating the coming of the 15" pair.

I like to think of it as a Whopper burger: luminous clouds of seasame bun halves that sandwich two thick & dark beef patties, with a sliver of lettuce peeking out from between them. Yummy.

Similarly, I always think of Centaurus A as the Big Mac Galaxy, because it is quite 'tall' compared to its width.