Comet Neowise

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Nifty
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Re: Comet Neowise

Post by Nifty »


elsie
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Re: Comet Neowise

Post by elsie »

This is one of the last photographs I took of the comet, on Sunday at 0:40. A 13s f5.6 ISO 1600 exposure (too long as it shows earth movement). It had become just about invisible to the naked eye by then and just a smear, partly because of the light pollution from the town a few miles away in the direction of the comet. It was much clearer with binoculars.
20200719_X7190604_EM1II_DxO-std-B&W.jpg

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Re: Comet Neowise

Post by Squinch »

Still a good picture Elsie.
I tried to get one and failed - a combination of unfamiliarity with the camera, poor eyesight in the dark and too much wine earlier.
It was still very impressive through the binoculars though.
Hopefully it stays clear for the next few nights but the forecast isn't great.

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Re: Comet Neowise

Post by clothmama »

crakpot wrote:
Mon Jul 20, 2020 12:08 am
Great sight below the Great Bear at 11.30 pm
I'm out to look! What way do I need to look??

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Re: Comet Neowise

Post by exile »

AS posted earlier - East of North low down on the horizon.

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Re: Comet Neowise

Post by Plog »

It's West of North at the moment..

Finally got some clear nights to watch it..sadly my pics aren't up to posting quality.

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Re: Comet Neowise

Post by elsie »

This site https://tinyurl.com/yy8e5utp will give you the direction to look in (it isn't necessarily East of North as it depends on the time/date/location you are looking from)
It is currently set for Clermont-Ferrand at 0:30 on 22 July. Hover your cursor over C/2020 F3 (NEOWISE) on the sky map and it will give you the altitude/height above horizon and the azimuth = direction in degrees from North (so 11.5º above horizon and 327º = NNW). By 4:00 on 22 Jul is only 2º above the horizon and 1º East of North. You can change the location by clicking on Clermont-Ferrand in the text and you can change the time by clicking on it.

It is becoming difficult to see without binoculars so that web page is very useful it giving you the information on where to look in the sky; a week or so ago it was magnitude 4 (the scale appears to work 'in reverse', with objects with a negative magnitude being brighter than those with a positive magnitude. The more negative the value, the brighter the object)
The magnitude in the example above is 6 = typical limit of naked eye. A magnitude of 10 = typical limit of 7×50 binoculars (from https://en.wikipedia.org/wiki/Magnitude ... _magnitude)

For anyone wanting to try to photograph it without showing earth movement blur you should use the "500" rule as a guideline for exposure https://astrobackyard.com/the-500-rule/ For the telephoto lens I was using for the photo above a setting to remove the blur would have been 1s f5.6 at ISO 25600.

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Re: Comet Neowise

Post by Plog »

Hi elsie

"a week or so ago it was magnitude 4 (the scale appears to work 'in reverse', with objects with a negative magnitude being brighter than those with a positive magnitude. The more negative the value, the brighter the object)
The magnitude in the example above is 6 = typical limit of naked eye. A magnitude of 10 = typical limit of 7×50 binoculars"

Being picky for a moment here but a magnitude 6 comet can be much harder to see then a magnitude 6 star because of the stars "output" is concentrated as a point whereas the comet is an area source..I suspect once the various "apps" and programs start quoting Neowise as being mag 5 it won't be naked eye.

I guess the message here is if you want to see Neowise there's no time to lose..

I'll declare an interest/bit of background here because when Hale-Bopp was around I was in the Uk with a proper astronomy set up and contributed some visual magnitude estimates to the BAA mainly using the "in-out" method .... :o :shock:

Which reminds me that now it looks like I'm going to have more time on my hands I really must get my kit set up properly again... :shock:

http://www.icq.eps.harvard.edu/MagScale.html
Note that a comet of magnitude 5 will not be as easy to see as a star of magnitude 5, because that same amount of brightness that is concentrated in a point for the star is spread out over a region of the sky for a diffuse comet with a relatively-large coma.

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Re: Comet Neowise

Post by elsie »

Plog wrote:
Tue Jul 21, 2020 6:24 pm
Hi elsie

"a week or so ago it was magnitude 4 (the scale appears to work 'in reverse', with objects with a negative magnitude being brighter than those with a positive magnitude. The more negative the value, the brighter the object)
The magnitude in the example above is 6 = typical limit of naked eye. A magnitude of 10 = typical limit of 7×50 binoculars"

Being picky for a moment here but a magnitude 6 comet can be much harder to see then a magnitude 6 star because of the stars "output" is concentrated as a point whereas the comet is an area source..I suspect once the various "apps" and programs start quoting Neowise as being mag 5 it won't be naked eye.

I guess the message here is if you want to see Neowise there's no time to lose..

I'll declare an interest/bit of background here because when Hale-Bopp was around I was in the Uk with a proper astronomy set up and contributed some visual magnitude estimates to the BAA mainly using the "in-out" method .... :o :shock:

Which reminds me that now it looks like I'm going to have more time on my hands I really must get my kit set up properly again... :shock:

http://www.icq.eps.harvard.edu/MagScale.html
Note that a comet of magnitude 5 will not be as easy to see as a star of magnitude 5, because that same amount of brightness that is concentrated in a point for the star is spread out over a region of the sky for a diffuse comet with a relatively-large coma.
I know very little about astronomy. I was just trying to get over the fact that it is getting further away quite rapidly and becoming less and less visible. I've not had a clear sky for a couple of nights so have not been able to check. Certainly when I took the photos the other night when the sky was clear it was easily visible at midnight (if you knew what to look for - I'd seen it on earlier days) but an hour later when it was nearer the horizon and into the light pollution it was invisible to the naked eye. Fortunately there was a bright star near to it which still provided a pointer (and was just about visible on my DSLR screen when turned to maximum).

I don't know how they are related, but web site I referred to has this further information https://theskylive.com/c2020f3-info: The current estimated magnitude of Comet C/2020 F3 (NEOWISE) is 6.00 (JPL) while the latest observed magnitude is 2.0 (COBS)

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Re: Comet Neowise

Post by Plog »

I know very little about astronomy.


Well regardless of that you certainly know enough about astronomy to take get a better image of Neowise than I managed the other night elsie. :good: :good:

My UK set up was a scope on a fixed pier with a driven (equatorial) mount so I was able to take fairly long exposures without the problem you mentioned abut stars "trailing". The hobby took a back seat when I moved here/kids/CIY etc, usual story....

BTW I'm not sure where The skylive website is getting it's COBS magnitude figure of 2 from.I've just had a look at the COBS site itself and whilst there is a lot a scatter in the figures they publish (and some real outliers) and their last observer to log anything last night estimated it as a 3.5... that's credible - then factor in it's a diffuse rather than a point source and the comet starts to get hard to see naked eye..you are certainly right in saying it is getting rapidly less and less visible.

Clear Skies.

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