Registration Fails WBPP On C/2023 A3

A

Andrew

Well-known member
I'm trying to figure out a solution to the registration failure in WBPP. I took 45 second exposures of Comet C/2023 A3 last night. I set my mount to track the comet as a custom rate, therefore. the comet is in the same spot in the subs, and the stars are all moving. Plus, I dither. I'm sure that has something to do with the failure. Is there a solution to this? Or, should I start over and use sidereal tracking to help with registration? Yep, my first attempt at comet processing.
Thanks in advance,
Andrew
 
Andrew said:
I'm trying to figure out a solution to the registration failure in WBPP. I took 45 second exposures of Comet C/2023 A3 last night. I set my mount to track the comet as a custom rate, therefore. the comet is in the same spot in the subs, and the stars are all moving. Plus, I dither. I'm sure that has something to do with the failure. Is there a solution to this? Or, should I start over and use sidereal tracking to help with registration? Yep, my first attempt at comet processing.
Thanks in advance,
Andrew
Click to expand...
Comet processing normally involves two alignment steps, one on the stars and one on the comet. When you're tracking on the comet, you may end up with stars too elongated for the StarAlignment process to work. Comet alignment uses a different process, where you identify the comet in each frame and then those frames are aligned (typically to the modeled comet core). What sort of processing are you performing?
 
Wow, I'm so sorry for taking so long to get back to this. I got called away right after posting this thread. I didn't mention that I had also taken a set of subs at sidereal rate so I have that to work with. I'm going to dump the subs I have tracking the comet. I'll work on using CometAlignment and report back.
Andrew
 
Andrew said:
Wow, I'm so sorry for taking so long to get back to this. I got called away right after posting this thread. I didn't mention that I had also taken a set of subs at sidereal rate so I have that to work with. I'm going to dump the subs I have tracking the comet. I'll work on using CometAlignment and report back.
Andrew
Click to expand...

FYI
I have created Comet Academy and demonstrate a vast majority of the permutations of cometary processing including this one.
See: https://www.adamblockstudios.com/categories/comet-academy (scroll down to the Comet-Tracked Star Streaked example)

There are other methods in addition to what Chris mentions above.
Just so you know, in this particular case CometAlignment needs to be used exclusively with manual selection of the comet *by clicking on it* in each frame. There is no linear motion and your results will be disappointing if you follow the typical usage of CA.
This explicit answer was ambiguously "hinted?" at by Chris. You do not typically identify the comet in each frame with CA- instead you rely on the motion of the comet as calculated from one frame to the next having identified in a subset of images. Your case with comet-tracked data is more of an exception to the rule.

-adam
 
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Andrew said:
Wow, I'm so sorry for taking so long to get back to this. I got called away right after posting this thread. I didn't mention that I had also taken a set of subs at sidereal rate so I have that to work with. I'm going to dump the subs I have tracking the comet. I'll work on using CometAlignment and report back.
Andrew
Click to expand...
There are a lot of variables in comet processing, so depending on lots of things (especially how fast the comet is moving against the stars) you need to look at different processing methods. I usually track on the comet and then deal with the stars in a separate run, sometimes after the comet has left that field. As Adam notes, when you're tracking on the comet you need to click on every comet image during CometAlignment (not just the endpoints as you can if you are working with images that are star aligned- only practical when the comet is moving slowly). Laborious if you have a lot of subs, but it works nicely.

The way I made this image (made with 30s exposures through red, green, and blue filters, tracking on the comet) was to run a normal WBPP to get the starfield image, where I masked out the smeared comet (which didn't move a lot against the background), and then ran CometAlign on the cosmetized images, which I integrated with a median operation and some pixel rejection, giving me a nice comet image without stars. I then combined the two. I didn't spend too long on this, as it's really just for my own use right now as I follow this object.

C_2023A3_20240517c.jpg
 
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Thank you all who are trying to help me. I need to put imaging and processing on hold for a while while I go into caregiver mode.
Hope to be back soon.
Andrew
 
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