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NEOWISE Looking Better from Southern California

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#1 james7ca

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Posted 16 July 2020 - 09:40 AM

I've been able to image NEOWISE at around 9PM PDT on both July 14 and 15 and the comet is getting close to being a naked eye object even from as far south as San Diego. How easy it will be to see NEOWISE will depend on the transparency of your skies and your levels of light pollution, but I'm hoping that by tonight (July 16) I will be able to see NEOWISE without optical aid from my red/orange zone light polluted location.

 

In any case, below is the image I took on the evening of July 15 at just after 9PM PDT. The comet is a fairly easy binocular object and does show a tail when observed with same, but I have yet to actually see the comet with my naked eyes (another San Diego observer, Tom Glenn, reported last night that he could not see the comet without binoculars).

 

The image below was taken with a 50mm Nikkor lens at around f/6 using a fixed tripod and an uncooled QHY5III-178C camera. This is a stack of 256 subs that were each exposed for 1.5 seconds, so the total integration time was about six minutes. A measurement taken on the photo indicated that the comet's tail is about three degrees long, but as the comet continues to rise higher in the sky over the next few days that should increase with the darker skies.

 

On the evening of July 14 NEOWISE appeared nearer to the lower right corner of the below image, just over two degrees lower in the sky (see next post with comparison image).

 

From my location near San Diego and at 9PM PDT NEOWISE will appear at an azimuth of around 319 degrees (toward the northwest) and at the following altitudes (approximately):

 

Thur, July 16:  11.3 degrees

Fri,   July 17:   13.7 degrees

Sat,  July 18:   16 degrees (Now we're talking! Still 11 degrees above the horizon at astronomical dusk.)

Sun, July 19:   18.5 degrees

 

On Wed, July 15 at 9PM PDT NEOWISE was at an altitude of 9 degrees (pictured below). On Tues, July 14 it was at 6.7 degrees (see composite image in the next post).

Attached Thumbnails

  • NEOWISE July 15 2020 (small).jpg

Edited by james7ca, 16 July 2020 - 10:38 AM.

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#2 james7ca

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Posted 16 July 2020 - 09:50 AM

Here is a composite image showing how far NEOWISE moved against the background stars in just 24 hours. These two images were star registered to one another, so the distance between the two positions is accurately represented. You can see from this overlay that NEWISE should be moving into fairly dark skies by the evening of July 16 (near to the upper left corner of this composite image --although still not in a  totally dark sky and the lucky people further north still have a significant advantage when viewing this comet).

 

Note, the bright area between the two dates is just the blending zone between the two images, although the sky conditions were dissimilar and I integrated a different numbers of subs on each night (the image from July 15 is a little "deeper"). The pair of stars that are near to the center of this composite appear in both images, toward the bottom in the image taken on July 15 (see above) and toward the top in the image taken a day earlier (see the below link).

 

You can view the full-sized image that I took on July 14 in the following thread here on CN:

 

  https://www.cloudyni.../#entry10339104

Attached Thumbnails

  • NEOWISE Movement July 14 and 15 2020 (small).jpg

Edited by james7ca, 16 July 2020 - 11:32 AM.

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#3 Tom Glenn

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Posted 16 July 2020 - 03:48 PM

James, nice image and thanks for summarizing the upcoming viewing elevations.  I agree that the comet could potentially become naked eye visible very soon, although it will probably not be a terribly dramatic view, unfortunately.  



#4 james7ca

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Posted 16 July 2020 - 08:37 PM

Tom, thanks for the notice.

 

I'm looking forward to this weekend since I should be able to use a tracking mount to image the comet from my normal observing location at my house (from the driveway). Prior to this time the comet was too low in the sky to be seen from that location. Unfortunately (for comet viewing), San Diego's typical marine layer cloud cover has been pretty early and thick recently and the weather forecasts for the next several days don't look very encouraging (I had scattered low clouds near to the comet on both July 14 and 15).

 

Plus, thus far the comet has been so low in the sky that I've had to use either my body or cardboard shields to block bright lights that were near to the horizon and casting glare into the camera lens.

 

Below is a snippet showing the forecast (from the Weather Underground) for the next week and note the cloud cover every evening (near 100%). Also, from my location in north county when they say "a few passing clouds," "mostly clear," or "partly cloudy" that means total overcast at night (usually around sundown). Thus, the "mostly clear" forecast for tonight doesn't mean much (except for clouds).   frown.gif

Attached Thumbnails

  • Cloud Cover Thru July 25.jpg

Edited by james7ca, 16 July 2020 - 08:42 PM.


#5 KiwiRay

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Posted 16 July 2020 - 09:31 PM

At the same time it's dimming fairly fast, but I guess that doesn't matter so much for imaging.



#6 james7ca

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Posted 16 July 2020 - 09:57 PM

At the same time it's dimming fairly fast, but I guess that doesn't matter so much for imaging.

Not so much if you can get it in a dark sky and use a tracking mount. But, my local skies are never dark given my light pollution and as shown in the weather forecast above the next week doesn't look good for clear nights.

 

However, I was able to use "The Photographer's Ephemeris" and SkySafari on my iPad to determine that I should be able to image NEOWISE from the far corner of my yard tonight with a pretty good horizon and no street lights directly in the field of view (right between the peaks of two rooflines that are across the street, but with a tall palm tree that should stay south of the comet) . So, I'm already starting to set up with the hopes that the skies will stay clear enough to image.




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