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DoomWillFindYou — NGC 281 - PacMan Nebula HaRGB
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Published: 2009-10-02 08:11:31 +0000 UTC; Views: 1358; Favourites: 15; Downloads: 64
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Description
Almost everything in the sky is numbered. NGC 281 is the 281st object (out of over 7800) in the New General Catalog - a listing of non-stellar objects found in the first sky-wide photographic survey done from the 1880's to the early 1900's. Unlike the Messier Catalog (numbering 109-110 depending on who you ask) which was discovered through random searches of the sky - so that sequentially numbered objects can jump all over the place - the NGC catalog was plotted from north to south by Right Ascension hour starting at 0hr and moving eastward in a full rotation around the earth. Other catalogs record different objects in different ways, and all those numbers can be hard to remember sometimes.Nicknames are often easier to remember than numbers. Someone in the 1970's said "hey, NGC 281 looks like PacMan!" and enough people agreed with him that the moniker stuck. The PacMan Nebula is a typical emission nebula lying 9500 LY from earth in the constellation of Cassiopeia, with reddish hydrogen ionized by hot young stars embedded inside. A Hydrogen Alpha filter was used in this image to enhance the structure in the nebula and set off some of the dark dust clouds nearby.
Takahashi EM-200 Temma Jr., Takahashi TSA-102 at f/6, FLI ML8300, Optec Ha (8nm) and LRGB filters. 210 min total exposure time.
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Comments: 8
Awesome!
How much processing do you do, and how do you occupy your time while waiting 210 minutes?
And how do you pinpoint where these nebulas are? =O
👍: 0 ⏩: 1
Thanks! With narrowband images like this, most of the processing is in Levels and Curves to get the image to look the way I want and in adjusting saturation to apply the shorter color exposures to the processed luminance data. I didn't need too much sharpening, as H-alpha is already very contrasty, and the long sub-exposures (20 minutes each) required only a little bit of noise reduction in the shadows.
I set up my sequence at 10 PM and walked around the dark sky site hanging out with friends camping nearby until the image acquisition had finished after 1:30 AM. The autoguider kept it locked onto the target the whole time, and I just had to pull the plug and throw the cover over the scope when it finished it's run.
👍: 0 ⏩: 1
That's neat! Thanks for explaining!
👍: 0 ⏩: 0
