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(1) M57 (4-07-02) (2) M57 with star magnitudes (3) Deep Sky Collage (4-07-02) |
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M57 (Mag 8.8) imaged 4-07-02 with Coolpix
995.
Imaged with AP155, Coolpix 995,
Pentax XL 40mm. Nine 60 second, ISO 400 images combined in AstroStack.
Temperature 30 F. The crescent Moon was up and the pre-dawn sunlight started
lighting up my images when I finished at 5:55am but the Coolpix still managed to
capture the Ring Nebula despite mediocre transparency. The cold temperature
definitely helped. I used a dark frame for 4 of the images and the camera's auto
NR (Noise Reduction) for the rest. I'm still experimenting to see which method
(under which conditions) captures the most detail. Postscript: Johannes Schedler
(http://panther-observatory.com) was kind enough to re-process my M57 and bring
out it's red halo. This has improved it greatly.
Gary Tollefson provided the following information
regarding star magnitudes around M57 which I've marked
above.
If you assume that M57 is a clock,
then, the star at about 7:00 o'clock is mag 15.7 according to Brian Skiff of
Lowell Observatory. Better yet, you will note a double star at about the 4:00
o'clock position. These two stars are typically rated at just below mag 15,
however, just to the right of the double (about 1/3 of the double-to-nebula
distance) is a very faint star that Skiff rates at mag 16.1 and directly below
that (by about the width of the central opening of the nebula) you have captured
a star that Skiff rates at 16.8. That is phenomenal! You have far exceeded
whatever I imagined might be possible with the equipment available to us.
BTW - the magnitude references come from the following source:
http://c3po.cochise.cc.az.us/astro/deepsky02.htm
About 2/3 of
the way down that page is a link to an image visually displaying the magnitudes
he references on his main page. The image can be accessed directly at:
http://c3po.cochise.cc.az.us/astro/images/M57!dss2_3.jpg
Gary
Tollefson
Imaged 4-7-02 with AP155 and Nikon CP995 at 60
second exposures, ISO 400.
I decided to do
a collage of all the deep sky images I managed to capture on 4-7-02.
Clockwise from upper left: M104 (Sombrero Galaxy), NGC2392 (Eskimo Nebula),
M51 (Whirlpool Galaxy), M64 (Blackeye Galaxy), M3 Globular Cluster, M57 (Ring
Nebula) and M27 (the Dumbbell Nebula). During my imaging session the temperature
ranged from a low of 30 F to a high of 44 F.
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