Beginner’s Guide: How to Capture Comet C/2025 R3 with Seestar S30 Pro
Planning
Comet hunting is all about timing and a little bit of luck. When a comet is known to be approaching earth it's important to check when it will be at its peak in brightness(magnitude) and whether or not it will be visible from your location and at what time. There are many planning tools and websites where this information is available. The Comet Observing database or COBS(https://cobs.si) and https://in-the-sky.org/ are great free resources for finding this sort of information. Depending on how bright the comet is you may consider finding a dark site to image from away from light pollution for best results. Lastly, clear skies are not guaranteed so don't think you need to wait until it's absolutely the brightest to go for it!
Setting up your Seestar for shooting
Should I choose EQ or alt/az? You can shoot in either mode very well but depending on how the comet tail is oriented one might consider how the sensor lines up with the comet tail and choose accordingly. On the inthesky website you can view what direction the tail will be at any particular time. You can also see if anyone else has posted images recently and what setup they used, this can help your decision. Shoot 10s images. Don't risk any dropped frames as the comet is very dynamic and changes quickly.
Choosing framing
Using the skyatlas you can search the comet and if you tap the "GoTo" it will automatically center the comet and this is not ideal framing. We want to get as much of the comet tail as possible! So we stop capture and move the frame so the comet is near the edge but not too close because the frames will move around a bit during capture (dithering).
How long should I shoot for?
This is up to you but because the comet will move seperately from the stars it will start to trail after a few minutes(this can vary). If you do not plan on stacking outside the app consider 3-5 mins max. If you decide you want to try comet stacking I would recommmend around 30mins if possible.
Can I use plan mode?
Yes however whenever you set up the plan in the app it is set in real time and the plan will not account for the comet movement so I do not recommend it for best results.
Now get out there and catch that comet!
All texts and images are credited to Jason Marriott. Special thanks to him for sharing.