5 replies to this topic

[pschmurr]

Observing in a Bortle 8 driveway with blinding neighbor security lights.  But still want to have some fun.  So I would like to take pictures with my smartphone of Mars and Jupiter against their closest visible background stars and somehow combine the images to record their change in position over time.  Can  anyone point me to some freeware suitable for this task and provide a procedural nudge or two?

[david_od]

I'd suggest putting your phone on some tripod or firm surface so your placement can be repeatable and reduce complications when producing the result. I'd also check on Stellarium the range of current and future visibility according to date, so you choose a framing that allows you both capturing the whole range of movement you intend to capture, while avoiding local obstacles and light sources (the latter in case you can only choose a few specific places).

You can use the stars visible at a given night as a reference for azimuth and altitude so you can choose the framing. Of course you could easily do this while moving relatively large distances between captures without much issue, but I just mention this in case you have some feasible placement constraints.

Ideally I'd suggest you to capture in raw format if possible, so denoising algorithms don't eat your stars. I'd take a few frames each night to you get a better quality image by stacking. A few dark frames, even if you don't use them at first, won't hurt and will allow you to control hot pixels.

The (optional) stacking and alignment can be done in Siril, but at least considering the current stable version you'll have to convert your raw images to a legible and appropriate format, like tiff. This can be done in DarkTable (free). If you didn't take dark frames, it has an option for removing hot pixels. Then if you want to stack per night, in Siril you can add a pile of images, star-align them, and then stack. You will probably need to choose a specific central region from the image so the alignment algorithm can work at al (this is why the framing is important as well, try to keep the range of motion of the planet as close to the center as possible). Once/when you have your sequence of single final images per night ready for alignment to visualize the motion, you add them to a sequence, star-align them, and here you can either stack them in "pixel maximum" mode (you'd have the planet in its multiple locations among fixed stars), or export the built sequence to inidivual frames in the "Sequence" tab, so you can add them on a different program, or create an animation. You hve here the possibility of cropping your area for exporting.

[pschmurr]

Thank you very much David!  I look forward to implementing your suggestions and sharing the results.

[Urban Uraniborg]

I made a GIF for my Saturn in Retrograde observations a couple years ago. I used Canon pocket point and shoot cameras IXUS & ELPH. NightCap is a decent app for apple devices. A high ISO setting and 10” to 15” seconds of exposure on a tripod while minimizing moon or neighborhood lights(I use a large piece of cardboard) should do it. No post processing for me just framing the two images and throwing them into a GIF maker. 

Edited by Urban Uraniborg, 05 February 2025 - 10:26 PM.

[pschmurr]

This is closer to what I was hoping to do.  I think I will begin with your approach and then learn more about post processing later. Did you use any tool to help you frame the images?

[Urban Uraniborg]

No tools except for the ones in the photo gallery. I crop each frame and ‘blink’ between frames. Adjusting the crop tool on the following frame(as many times as it takes) until it fits with previous one. Below is attached the original photo (2nd frame) of the Saturn month GIF so you can see how far I zoomed into each frame. 

 

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