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So, I was always amazed by images of NEOWISE around the Internet like this:

neowise_bright_1 Or this:

neowise_bright_2

Yet, all my efforts to see it or photograph it in its full glory were fruitless...

my_dimm_neowise_1 22.07.2020 22:01

Here you can barely see it at the bottom-left of the image... my_dimm_neowise_2 24.07.2020 22:00

Here is the zoomed version... Very very blurry. The point is that I couldn't even see it with my "naked eye" (well I couldn't see it even if it were much brighter, because I use glasses, and that's automatically not "naked eye", but yea). The maximum that I could see was just some smudge. With 5x binoculars I could see it, again super dim and blurry. I decided to purchase a telescope specially for this, and although I could see Jupiter's moons and Saturn's ring quite clearly, I had no success with NEOWISE. Both at 56x and 140x zoom the comet seemed super blurry and dim. Although stars around it were in good focus, no matter how I tried to focus the comet itself, it always seemed out of focus...

BTW, these 2 shots were taken at the closest approach to Earth around 2

So I thought, maybe it's because of light pollution? I live in a not-super-giant city, but a light pollution map showed some amount of pollution still. So I went to a light grey area (only one step brighter than black) on the map. This, however didn't change much at all...

neowise_bright_2 25.07.2020 22:32

The comet is still very dim and small. I couldn't find it with the "naked eye" reliably. Its size is almost the same as surrounding stars, yet on other people's photos it appears like 10 times bigger than the stars around it!

What could be the reason for this? If not light pollution, maybe it's that my location is very bad for viewing it? I'm located in southern Ukraine, Kherson city.

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    $\begingroup$ I think you've taken a fine image. Nobody said astrophotograph was easy! I can see the comet, its tail, even some colour. Well done! The pro photographs are done with top-end equipment, lots of experience and a good dose of luck. You only see the best when you search the internet, you don't see all the images that were discarded. Be proud of your image, that's a good result! $\endgroup$
    – James K
    Jul 26, 2020 at 19:12
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    $\begingroup$ That's much better than what I have been able to see. That said, north for me is toward a city of several million. On a very good night in the middle of winter I'm lucky to be able see more than ten stars across the entire sky. Saturn, which is not to the north, is barely visible to me currently at magnitude 0.92.. Light pollution is a nasty problem. $\endgroup$
    – David Hammen
    Jul 27, 2020 at 3:34

2 Answers 2

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There's one main reason - and maybe some other reasons as well:

The primary reason is the date the photos were taken you compare your photo with. Two weeks ago (10th July 2020), the brightness of the comet was around 1 - 2 magnitudes - that is comparable to the brighter stars and it was readily visible with the unaided eye on onset of nautical twilight. A week later already (17th July) it moved further from the sun and it was only around 3.5 magnitudes (personal guestimate from comparison with surrounding stars like some from Canis Minor) - thus it needed already a dark sky to be nicely visible. Now is already another week past and its heliocentric distance increased further, its brightness dropped to something comparable to the stars just barely visible with the naked eye. Conversely its activity also reduced dramatically with increasing heliocentric distance. As it meanwhile has past its perihelion as well as closest approach to Earth, it's meanwhile both effects adding up: geometry and much less material to scatter the sunlight due to reduced activity.

See this animation for a trajectory.

While the pure physics above are the main reason for the difference, other reasons might be the amount and skill of post-processing done on images. People might have stacked several photos in order to gain a higher noise-to-contrast ratio and applied a logarithmic brightness curve or similar.

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  • $\begingroup$ vimeo.com/436480256 On this timelapse (july 8) comet is super big and bright. I doubt that author took multiple exposures and stacked them in this timelapase, and your explanation due to proximity to Sun is most accurate. I suspected this, but hoped that proximity to Earth would counteract this. But alas! $\endgroup$
    – ScienceDiscoverer
    Jul 30, 2020 at 6:39
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Allow me to coin a phrase. Phonygraphic.

Without getting into specific details, the first two images are the result of camera tricks and image processing.

The two photos 25.07.2020 22:32 and 24.07.2020 22:00 are in keeping with what I could see of the comet with my unaided eyes from a dark site between July 15 and July 23 2020. By the twenty third the comet was no longer visible to the naked eye at my location.

I suggest you Google Astrophotography for a good explanation of the photographic techniques used to capture images of very dim astronomical objects

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  • $\begingroup$ Yea, I learned how people are picturing distant galaxies with thousand dollars worth of equipment and 8 hours of multiple exposures... I just didn't suspect they used same tricks on the comet, because it's much brighter. $\endgroup$
    – ScienceDiscoverer
    Jul 30, 2020 at 6:31

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