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View Full Version here: : Messier22 with *istDS and C9.25


Dennis
25-04-2006, 03:30 PM
Here is an image of M22 I grabbed last night after giving up on Jupiter due to the poor seeing. The image has been resampled from the original 3000 x 2000 pixels, cropped and saved as a 40% compression jpg.

From Starry Night Pro.
M22 is a magnitude 5.09 Globular cluster in the Constellation of Sagittarius, The Archer. The angular size is 24 arc minutes.

Globular clusters are densely packed balls of stars. From 50 000 up to 2 000 000 stars are bound together in a sphere with a radius of no more than 100 light years. All of the Milky Way’s globular clusters are ancient, up to 15 billion years old. At least 149 globular clusters in the Milky Way have been discovered, and more than 100 are in the NGC-IC catalog. Their distribution forms a spherical halo, centred on the core of our Milky Way.

According to SkyTools, there is a small planetary in M22 as follows:
GJJC 1
Planetary Nebula
aka PN G009.8-07.5
RA: 18h36m23.4s, Dec: -23°55'20" (2000) in Sagittarius
Magnitude: 15.00
Size: 8.5"

Unfortunately, I cannot locate it in my image as the stellar population is too dense.

Image details:
Celestron C9.25 with f6.3 focal reducer.
Pentax *istDS DSLR camera.
10 x 30 sec exposures.
Suburban Brisbane.
24th April 2006
Aligned and stacked in ImagesPlus.

http links:
SNP: http://www.starrynight.com/
SkyTools: http://www.skyhound.com/skytools.html
ImagesPlus: http://www.mlunsold.com/menu.html

This was my first serious effort at imaging through the C9.25 with the Pentax *istDS and it is a much more difficult undertaking than using the smaller, more automated and software integrated, SBIG ST7e ccd camera.

Cheers

Dennis

h0ughy
25-04-2006, 03:37 PM
Congrats Dennis, an excellent capture there. THe pentax is a good camera! did you do darks and flats etc?

Dennis
25-04-2006, 04:11 PM
Hi Dave

No flats, but the image is cropped from the centre of the full frame which was badly vignetted and had a couple of dust bunnies. I think that the Pentax did the auto-darks for each 30 sec exposure, as I was using the interval function of the Pentax remote Assistant software.

Cheers

Dennis

h0ughy
25-04-2006, 04:15 PM
does the *istD software work for the DS? I didnt think it supported the DS? So did you focus using the software?:)

Dennis
25-04-2006, 05:32 PM
The basic functions work via the software. For interval shooting, you are restricted to the range of shutter speeds 1/4000 to 30 secs when you set the dial to manual, and you must also enable the non-A lens setting on panel 3 of the Custom settings in the camera.

If you want to take, say 60 second exposures, you have to set the camera to B and the software will not allow interval shooting.

I have a Series IV 'Stiletto' Focusers for 35mm Digital SLRs seen here:
http://www.stellar-international.com/
IMO this is essential for critical focusing.

Cheers

Dennis

sheeny
25-04-2006, 05:51 PM
Very nice image, as usual, Dennis.

And thanks for the link anout the Stilletto focusser. Looks like an excellent piece of kit!

Al.