Follow minor planet - or comet

Image processing, astrometry, photometry, etc.
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einari
Posts: 35
Joined: 28 Jan 2019, 10:46

Follow minor planet - or comet

Post by einari » 13 Apr 2020, 15:12

I'm assuming asteroid or comet align assumes that north is up (and east west) in images.
How about when camera is not rotated like that ?
Would it be possible to read angle from fits and then calculate the angle of asteroid/comet based on that ?

fabdev
Posts: 354
Joined: 03 Dec 2018, 21:43

Re: Follow minor planet - or comet

Post by fabdev » 13 Apr 2020, 18:03

Hello,
you need to carefully measure the rotation angle and pixel scale: do a plate solve, then open Statistics, note the Angle in "Field of view" line and the Pixel Scale.

These values must be set in the Observer/Camera settings.

einari
Posts: 35
Joined: 28 Jan 2019, 10:46

Re: Follow minor planet - or comet

Post by einari » 13 Apr 2020, 19:17

I tried but it doesn' t look much better.
Is negative camera angle valid ?

fabdev
Posts: 354
Joined: 03 Dec 2018, 21:43

Re: Follow minor planet - or comet

Post by fabdev » 14 Apr 2020, 18:44

Yes of course.
If you calculate the comet speed and angle with Astroart (the "Find" button) remember to have an updated CometEls.txt file, in any case you may check with the MPC values. If the comet is close to Earth, verify that the observatory coordinates are correct.

einari
Posts: 35
Joined: 28 Jan 2019, 10:46

Re: Follow minor planet - or comet

Post by einari » 30 Apr 2020, 19:01

Back to this.

Today I made a macro to rotate all comet files so they would be north/south.
And now the follow minor planet aligning worked.

einari
Posts: 35
Joined: 28 Jan 2019, 10:46

Re: Follow minor planet - or comet

Post by einari » 08 Jan 2022, 09:09

I would still like to make this work (without rotating images).
I plate solve image and get -92.65 as camera rotation angle.
Put this in Observatory data. Get current comet data (angle and speed).
And the result is image attached.

Does it make difference that in fits the camera angle is 88 (SGP puts it there) ?
Attachments
AA7-comet-stack_2022-01-08 105905.jpg

fabdev
Posts: 354
Joined: 03 Dec 2018, 21:43

Re: Follow minor planet - or comet

Post by fabdev » 09 Jan 2022, 17:49

Are these the same images of 2020 that worked if rotated manually ?
If not, do they work if rotated before ?

einari
Posts: 35
Joined: 28 Jan 2019, 10:46

Re: Follow minor planet - or comet

Post by einari » 13 Jan 2022, 05:19

I guess they work if they are rotated. But was hoping it would work without doing it.
Guess I would like an explanation why they need to be rotated before the follow comet stacking works.

Edit: I think I got it working now.
My rotation angle is now -87.07 ( in Observer settings).

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