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C/2022 E3 ZTF this morning (1/22/2023)

Kirby Collins
 

I finally got a full night with no clouds, so I went back to C/2022 E3.   Horizons was really pretty straightforward, especially after watching Ray's video.  And imaging unguided really does simplify things. 

Anyway attached is an initial cut at last night's data:

Astrotech 115mm refractor at f/5.6
ZWO ASI294MC OSC camera, ZWO EAF electronic focuser
Mach2/APCC/Horizons, SGP for imaging
polar aligned with Sharpcap
266 point model built while waiting for the target to get high enough
Processed with PixInsight

I took 240x60 second subs between 0130 and 0530, but only used the last 120.  I was surprised to see a diffuse "tail" stretching up and to the left (towards the Sun), on the opposite side of the main dust and ion tails.  This is also visible in the image midmoastro posted, and on at least one of the images on Astrobin, so it's not an artifact.  Perhaps dust shed on the comet's way in towards the Sun, and still following in more or less the same orbit?


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Kirby Collins

astrobin: https://www.astrobin.com/users/kirbycollins80

Alex
 

https://www.sott.net/article/476542-Anti-tail-appears-on-Comet-E3-ZTF-becomes-visible-to-unaided-eye-1-week-earlier-than-expected

Kirby Collins
 

I hadn't heard of anti-tails before.  Thanks!
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Kirby Collins

astrobin: https://www.astrobin.com/users/kirbycollins80

Shailesh Trivedi
 

Kirby,

Intriguing but looks like the anti tail is perhaps due to the gravitational pull of the sun.

How did you use Horizons and SGP for this capture? 

Shailesh

Howard Ritter
 

No, not the Sun’s gravitation. That would affect all parts of the comet equally, at least to a first approximation. Tails and anti-tails obey the laws of celestial mechanics, after the particles that form them have been emitted from the surface and been pushed around by solar radiation and solar wind.

Anti-tails are uncommon but well known, and C/2022 E3 ZTF has developed one. Here’s the best summary I’ve found of this developement:

—howard

On Jan 23, 2023, at 12:20 PM, Shailesh Trivedi <shailesh.trivedi@...> wrote:

Kirby,

Intriguing but looks like the anti tail is perhaps due to the gravitational pull of the sun.

How did you use Horizons and SGP for this capture? 

Shailesh

Kirby Collins
 

In truth this is my first comet since I got the Mach 2 so I'm still figuring it out.  But I just tried to let APCC/Horizons do all the work of pointing and tracking, and just used SGP to take the images.  Here are the details:

1.  Start APCC & connect to mount
2.  polar align with Sharpcap
3.  Start SGP & connect to camera & focuser
4.  Autofocus with SGP
5. Start APPM and build model
6. Start Horizons, enter comet data, & start tracking...Horizon will initate slew and center comet nucleus
7. Take a test image with SGP "frame and focus"
8. Nudge mount with APCC to put nucleus off-center so I could image more tail
9. Set up imaging sequence
  - make sure slew and center options are not checked in target info dialogue
  - turn off dithering
10.  Start sequence and go to bed

The key thing is make sure SGP never tries to move the scope.  It's not clear to me if custom tracking disables dithering, but I turned it off anyway, in the hopes the comet tracking is good enough I can just stack without having to align the comet.  I also didn't have to worry about a meridian flip...it never got that high.  Not sure a meridian flip makes sense with comet tracking anyway.

As I said I'm still figuring this out, helpful hints from the more experienced are appreciated.
--
Kirby Collins

astrobin: https://www.astrobin.com/users/kirbycollins80

Shailesh Trivedi
 

Thank you Kirby

Dean Jacobsen
 

Really nice image Kirby.
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Dean Jacobsen
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/

Kanwar
 

Hello,

I am trying to capture comet using mono camera. I followed the steps Kirby mentioned and able to track the comet and take images to verify. All good but not sure how to proceed with mono setup to capture just one frame :(

Any suggestions?

Thanks,
Kanwar

Kirby Collins
 

Do you mean take RGB subs and combine with your mono camera and combine them for a color image?  I’ve always used an OSC for things that move fast like comets so I didn’t have to deal with the misalignment of the RGB subs.  But it might actually work with comet tracking, because you won’t need to align the comet if the tracking is good enough.  The stars will have misaligned RGB, but you are going to try to get rid of the stars when you integrate anyway.  Then you can either try to star align your subs to get a normal RGB star mask to combine with your comet image.  Star trailing may mess up you star alignment though if your subs are very long.


--
Kirby Collins

astrobin: https://www.astrobin.com/users/kirbycollins80

Brian Valente
 

HI  Kanwar

for a mono camera, it is pretty much the same approach, but most mono imagers rotate the filters: expose red, switch and 1 exposure green, switch and 1 exposure blue, repeat

Building the star masters is the same process you would normally do, but then there's building the comet masters, With PixInsight's latest comet alignment, you can load all the different filters into one session and they will all comet align

It's a variation of register and integrate stars, then register and integrate comet, then blend them together


hth

Brian

On Thu, Jan 26, 2023 at 6:17 PM Kanwar <brar.kevin@...> wrote:
Hello,

I am trying to capture comet using mono camera. I followed the steps Kirby mentioned and able to track the comet and take images to verify. All good but not sure how to proceed with mono setup to capture just one frame :(

Any suggestions?

Thanks,
Kanwar



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Kanwar
 

Kirby,

You are correct. I meant LRGB subs using my mono setup and then generate final color image. I have similar concerns as you mentioned. My hope is CometAlignment in Pixinsight would do its magic on the data.

I have captured 30x30 frames with each LRGB filter. I am new to AP mount, so, I was really amazed how Horizons software tracked the comet. I had to explain it to my club members how I was doing it :)


Kanwar
astrobin: https://www.astrobin.com/users/brarkevin/

Brian Valente
 

Kanwar

PS - I may be repeating myself but PixInsight released a complete rewrite of the comet alignment process which will work much better for mono+filters

It has great documentation to go with it

here's a link to their video overview of the new ca process version https://www.youtube.com/watch?v=Jp4JhiBm8L4

On Thu, Jan 26, 2023 at 8:59 PM Kanwar <brar.kevin@...> wrote:
Kirby,

You are correct. I meant LRGB subs using my mono setup and then generate final color image. I have similar concerns as you mentioned. My hope is CometAlignment in Pixinsight would do its magic on the data.

I have captured 30x30 frames with each LRGB filter. I am new to AP mount, so, I was really amazed how Horizons software tracked the comet. I had to explain it to my club members how I was doing it :)


Kanwar
astrobin: https://www.astrobin.com/users/brarkevin/



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Kanwar
 

Brian,

I really appreciate the link and correcting me on my process. I messed up and did not cycle between the filters. I will try to capture it again tomorrow.

Brian Valente
 

I think you can still process it even if you captured the filters sequentially, give it a shot with the new process!


On Thu, Jan 26, 2023 at 9:48 PM Kanwar <brar.kevin@...> wrote:
Brian,

I really appreciate the link and correcting me on my process. I messed up and did not cycle between the filters. I will try to capture it again tomorrow.



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Kirby Collins
 

I actually took three different sets of subs that night (I wasn't quite sure how this was going to work)...first 30x60 seconds with normal sidereal tracking, then started comet tracking with Horizons, took a few 120 second subs and decided I didn't like how much the stars were trailing, then took 60x30 subs (with comet tracking), and finally 240x60 seconds (also with comet tracking).  The first sets were while the comet was still low over Albuquerque and the quality wasn't great, but I was thinking I would just try to get round stars from one of those to combine with the main 60 second comet aligned set. 

I took a look at how well the comet was tracked by using the comet alignment process to find the centroid of the comet across the sequence of 60 second subs (four hours total of comet tracking).  For what it's worth here are the pixel x,y values for the comet center across that span (oriented so x direction is mostly declination, multiply by my image scale of 1.48 to get arcseconds):

sub: x, y
 1: 1447.61, 1132.58
31: 1447.51, 1128.01
61: 1448.97, 1125.41
91: 1450.64, 1124.51
121: 1453.33, 1123.68
151: 1456.15, 1122.80
181: 1458.40, 1121.98
211: 1461.45, 1122.36
240: 1465.33, 1123.81

The first hour or two the comet was pretty low, and the quality of the subs wasn't great, so I just used the last two hours....in that span I had about 18 arcseconds (12 pixels) of drift in DEC, and none in RA.  I tried both simply stacking the subs as-is without any further alignment, and using the comet alignment tool to adjust for the drift.  I couldn't see a difference in the integrated result, so I just used the simple stack.  For the integration step I used Linear Fit pixel rejection to get rid of the stars, clipping values of 4 for low and 0.85 for high seemed to work best for this data set.  Note I had a lot of subs with a lot of movement from start to finish, so getting rid of the stars was relatively easy.  For a quick process I just used ABE, NoiseXterminator, HistogramTransformation, and a light touch of CurvesTransformation for contrast and saturation.  For the star background I just star aligned the subs, then used StarNet2 to get a star only mask.  Then I combined the two with PixelMath using a simple max of the comet and star images.  You can see a slight bit of trailing in the resulting image, even though the subs were just 60 seconds.

I later went back and did another pass at processing, this time using the star background from the 30x60 second sidereal tracking set so I had nice round stars.  Purists might object to this, since the star background I used wasn't actually from the same dataset as the comet data.  The comet did pass through this area, but since I'm combining data from two different times I may not have it in exactly the correct position relative to the background.  I also stretched the stars a bit more so they are more prominent, and tried to do a better job on the comet data.  Attached is the result...to be honest I don't think it is better than my quick pass.

C2022E3_combined.jpg


On Thu, Jan 26, 2023 at 10:09 PM Brian Valente <bvalente@...> wrote:
Kanwar

PS - I may be repeating myself but PixInsight released a complete rewrite of the comet alignment process which will work much better for mono+filters

It has great documentation to go with it

here's a link to their video overview of the new ca process version https://www.youtube.com/watch?v=Jp4JhiBm8L4

On Thu, Jan 26, 2023 at 8:59 PM Kanwar <brar.kevin@...> wrote:
Kirby,

You are correct. I meant LRGB subs using my mono setup and then generate final color image. I have similar concerns as you mentioned. My hope is CometAlignment in Pixinsight would do its magic on the data.

I have captured 30x30 frames with each LRGB filter. I am new to AP mount, so, I was really amazed how Horizons software tracked the comet. I had to explain it to my club members how I was doing it :)


Kanwar
astrobin: https://www.astrobin.com/users/brarkevin/



--


--
Kirby Collins

astrobin: https://www.astrobin.com/users/kirbycollins80

Kirby Collins
 

By the way another clear night here in New Mexico, we will see if I can do better tonight ;-).
--
Kirby Collins

astrobin: https://www.astrobin.com/users/kirbycollins80

Stuart
 

Kirby, this is a fascinating thread and I really appreciate all the detail you're providing. The pics are super! Good luck tonight!


On Mon, 23 Jan 2023 at 01:25, Kirby Collins <kirbycollins80@...> wrote:
I finally got a full night with no clouds, so I went back to C/2022 E3.   Horizons was really pretty straightforward, especially after watching Ray's video.  And imaging unguided really does simplify things. 

Anyway attached is an initial cut at last night's data:

Astrotech 115mm refractor at f/5.6
ZWO ASI294MC OSC camera, ZWO EAF electronic focuser
Mach2/APCC/Horizons, SGP for imaging
polar aligned with Sharpcap
266 point model built while waiting for the target to get high enough
Processed with PixInsight

I took 240x60 second subs between 0130 and 0530, but only used the last 120.  I was surprised to see a diffuse "tail" stretching up and to the left (towards the Sun), on the opposite side of the main dust and ion tails.  This is also visible in the image midmoastro posted, and on at least one of the images on Astrobin, so it's not an artifact.  Perhaps dust shed on the comet's way in towards the Sun, and still following in more or less the same orbit?


--
Kirby Collins

astrobin: https://www.astrobin.com/users/kirbycollins80

Kanwar
 

Finally, I was able to capture and process the comet. After acquiring new AP1100 week back and still learning how to use it, so, never thought it was possible without the help from this group!!

R : 35*45s
G : 35*45s
B : 35*45s

--
Kanwar

https://www.astrobin.com/users/brarkevin/

Brian Valente
 

wow it's a beautiful shot, congrats Kanwar!



On Sat, Jan 28, 2023 at 9:15 PM Kanwar <brar.kevin@...> wrote:
Finally, I was able to capture and process the comet. After acquiring new AP1100 week back and still learning how to use it, so, never thought it was possible without the help from this group!!

R : 35*45s
G : 35*45s
B : 35*45s

--
Kanwar

https://www.astrobin.com/users/brarkevin/



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