APOD: Whirlpool with Comets (2016 Dec 08)

Comments and questions about the APOD on the main view screen.
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APOD Robot
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APOD: Whirlpool with Comets (2016 Dec 08)

Post by APOD Robot » Thu Dec 08, 2016 5:09 am

Image Whirlpool with Comets

Explanation: Not a comet, bright spiral galaxy Messier 51 is popularly known as the Whirlpool Galaxy. Just off the handle of the Big Dipper in northern skies, you can spot it at the upper left in this image from December 1st. The pretty 4 by 2.5 degree wide field of view does contain two comets though. Different in appearance, both comets are new visitors to the inner Solar System and are currently faint telescopic objects, highest above northern horizons in morning twilight. At lower left newly discovered comet NEOWISE (C/2016 U1) shows off a round fuzzy coma in the greenish light of diatomic carbon gas fluorescing in sunlight. Sunlight reflects from dust in the coma and stubby tail of comet Johnson (C/2015 V2) at upper right.

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RocketRon

Re: APOD: Whirlpool with Comets (2016 Dec 08)

Post by RocketRon » Thu Dec 08, 2016 5:14 am

There is a typo in the main date here - 3rd Dec not the 8th Dec.

Are comets becoming more numerous that 2 can be observed in a fairly narrow angle view.
Or just better observed ?

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Chris Peterson
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Re: APOD: Whirlpool with Comets (2016 Dec 08)

Post by Chris Peterson » Thu Dec 08, 2016 5:23 am

RocketRon wrote:Are comets becoming more numerous that 2 can be observed in a fairly narrow angle view.
Or just better observed ?
Neither, I think. There have been quite a few images posted here and elsewhere in recent years showing more than one comet in the same field.
Chris

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Case
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Re: APOD: Whirlpool with Comets (2016 Dec 08)

Post by Case » Thu Dec 08, 2016 1:02 pm

One of the more significant deep sky objects in the constellation Canes Venatici (the Hunting Dogs) is the Whirlpool Galaxy (M51), the merger of the blueish spiral and the yellowish companion. Nice to see the galaxy in this portrait. Note how “solid”/even level the galaxy disk looks in todays APOD, compared to other images of M51 with contrast adjusted to show detail in the spiral arms and the “gaps” between them.

Mr. Chambó mentions using a Mayhill, New Mexico (USA) facility, which I interpret as the New Mexico Skies Observatories, which houses quite a few remotely operated telescopes, including for some big names.
He also mentions L:3×180s Bin1 + RGB:1x60s Bin2, which is only 10 minutes of exposure time combined, if I understand the notation correctly.

Some comets move relatively fast compared to the background star field. Astrophotographers and their software may have to process the comet(s) separately from the “static” star field, if the comets move noticeably during imaging. I think this would be needed for “close-ups” of a (small) comet. For “wide” field photography and short exposure time, this special treatment may not be necessary, right?

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Ann
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Re: APOD: Whirlpool with Comets (2016 Dec 08)

Post by Ann » Thu Dec 08, 2016 2:20 pm

I note that Comet NEOWISE is a nice blue-green color, while Comet Johnson is a nondescript white.

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TempUser

Re: APOD: Whirlpool with Comets (2016 Dec 08)

Post by TempUser » Thu Dec 08, 2016 2:32 pm

Is that another comet at the bottom of the image, ~4 o'clock from Neowise?

ruth_sandy_panzard

Re: APOD: Whirlpool with Comets (2016 Dec 08)

Post by ruth_sandy_panzard » Thu Dec 08, 2016 4:06 pm

Please check the date over today's picture. SAP)

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RJN
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Re: APOD: Whirlpool with Comets (2016 Dec 08)

Post by RJN » Thu Dec 08, 2016 4:11 pm

RocketRon wrote:There is a typo in the main date here - 3rd Dec not the 8th Dec.
Thanks! Fixed it. - RJN

heehaw

Re: APOD: Whirlpool with Comets (2016 Dec 08)

Post by heehaw » Thu Dec 08, 2016 9:49 pm

It is nice to see M51 "from a distance," so to speak: that is, in a much wider field. I've never seen it that way before. It is a very nice, very familiar, galaxy.