#### How do you do a comet mosaic - the tail ain't easy?

Nick Iversen

Getting an image of a comet head using Horizons is easy. But comets 2021 A1 (Leonard) from last year and 2022 E3 (ZTF) have long tails and so a mosaic is necessary to get it all in. I missed the tail of Leonard because it took me a couple of nights to figure out where the tail was and then clouds set in.

So what is the best way to get the camera angle and RA, Dec coordinates for a mosaic? Maybe NINA can do it in a drag-and-drop way from a plate-solved image. My method used a rule and a calculator which isn't 100% reliable.

Once you have RA and Dec coordinates you still have to get Horizons to track the tail.

Nathan Myhrvold

If you have some stars as landmarks, you can use Telescopius  - the Telescope Simulator does mosaic calculations and lets you specify a comet by position of coma and then the length and direction of the tail.   This gives you a CSV file – I have not tried to import into NINA but the data is there – it is just a matter of the input format.

Nathan

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Nick Iversen via groups.io
Sent: Wednesday, January 11, 2023 3:28 PM
To: main@ap-gto.groups.io
Subject: [EXTERNAL] [ap-gto] How do you do a comet mosaic - the tail ain't easy?

Getting an image of a comet head using Horizons is easy. But comets 2021 A1 (Leonard) from last year and 2022 E3 (ZTF) have long tails and so a mosaic is necessary to get it all in. I missed the tail of Leonard because it took me a couple of nights to figure out where the tail was and then clouds set in.

So what is the best way to get the camera angle and RA, Dec coordinates for a mosaic? Maybe NINA can do it in a drag-and-drop way from a plate-solved image. My method used a rule and a calculator which isn't 100% reliable.

Once you have RA and Dec coordinates you still have to get Horizons to track the tail.

Nick Iversen

Thanks, Nathan. Pretty good advice. It even draws the comet tails for me. It also has an export for NINA. I couldn't figure out how to rotate the mosaic, however. And do you think the tail simulation is accurate? Length and angle?

Patrick Sparkman

You rotate the mosaic by rotating the camera with the bottom slider of the camera tab.

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