Initial attempts at Jupiter

[John_D]

This is an attempt at Jupiter ( and Io ) with my TAL 6" reflector taken on 14/11. The initial plan was to use my Nikon D3100 DSLR to take the video but the D3100 has very little manual control over exposure in video mode and, in earlier tests, the planet was just too over-exposed whatever I did. There is an exposure compensation control but this achieves the result by modifying the lens aperture which of course isn't going to work when the camera is attached to a telescope!  So I splashed out on a ZWO ASI 120MC camera which is what was used here.

Ideally I'd like some more magnification and I think that a 2.5x Barlow would be the optimum size for this setup. However when I bought the telescope I got a TAL 4x Barlow with it so I'll experiment with that first.

One problem that I had was that I captured the video using AstroDMx on an old laptop ( running Lubuntu 22.04 ) with only 4Gbyte of RAM and no USB 3 port. I was generally getting about 30 fps but, on occasion, it would drop down to about 8 fps for no apparent reason. I suspect that things like auto-update checks were getting in the way. I need to see what services I can turn off and maybe increase the priority of AstroDMx as well. Failing that I'll have to lever open the wallet again and get more RAM and an SSD.

The processing used PIPP / Autostakkert / Registax all running under Wine on my desktop Ubuntu 22.04 PC. It was a 3 min video of ~5000 frames, the best 1500 selected by PIPP and the best 25% stacked in Autostakkert. I have no idea whether those numbers are sensible or not! I also did some final cropping and tweaks using GIMP.

Now waiting for the clouds to clear so that I can try the Barlow ...

[geoflewis]

That's a nice first image of Jupiter, well done. The main features are well seen and despite the small image size, it looks like you've got some detail coming through too. I'm not familiar with AstroDMx, so does it allow you to set an ROI around the planet, to increase capture frame rates? 30fps should give you good results, but 8fps is definitely going to be more challenging.

[John_D]

5 hours ago, geoflewis said:

That's a nice first image of Jupiter, well done. The main features are well seen and despite the small image size, it looks like you've got some detail coming through too. I'm not familiar with AstroDMx, so does it allow you to set an ROI around the planet, to increase capture frame rates? 30fps should give you good results, but 8fps is definitely going to be more challenging.

Thanks.  

Yes AstroDMx allows you to set an ROI. At the moment, mainly I think because I'm using USB2, I'm getting roughly half the maximum specified frame rate from the camera:

1280 x 960 - 30 fps vs 60 fps max
800 x 600 - 48 fps vs 85 fps max

This will be fine as long as I can work out what's causing the occasional drop in frame rates. At the moment it could be anything from extraneous processes to bottlenecks writing to disk. Things like turning off the real time Debayering doesn't seem to make any difference.

[John_D]

A quick follow up to my original post. After some technical issues ( see below for details ), the inevitable cloudy skies and the purchase of a budget 2x Barlow during the FLO Black Friday sale I came up with a short animation Ganymede disappearing behind Jupiter the other night:

I was actually testing varying exposure times to see what difference it made - answer, not much when you're capturing raw. Then I realised that I could string them together into a basic animated GIF. I think that the seeing was quite poor, certainly the video that I took of the moon looked as if it was from the bottom of a swimming pool. Hopefully future images will be a little sharper.

A couple of questions:

1. I don't think that the red splodge at the bottom is the great red spot because the first image was taken at 23:20 on 19/12/23 which doesn't line up with any online transit predictions or the image on Stellarium. Any suggestions on what it might be are gratefully received.
2. Is there a convention as to how these images should be presented, e.g. north pole at the top?

Technical comments:

• I failed to work out what was causing the problem with the frame rate drops. Both AstroDMx and FireCapture exhibited this problem on the laptop but not on my desktop machine. However ZWO supply an app called ASIStudio which is a much simpler tool than the other two but, other than not having an ROI feature, it does all I want. More importantly the frame rate stays constant. The 8 frames in the GIF were all 120s long and captured at ~28 FPS which is fine for an ancient laptop and USB2.
• PIPP absolutely refused to debayer the raw video correctly. Whatever setting I used just resulted in a strange purple hue to the output. I "fixed" the problem by getting AutoStakkert! to do the debayering instead which worked fine. The only wrinkle was to tick the "Protect Bayer Pattern When Centering/Cropping" box on the "Input Options" tab in PIPP.

[Astronomist]

My frame rate sometimes drops from an already pathetic 18fps down to 3 or 4, I figured out recently that this was caused by the laptop getting too cold. No idea if this is what is causing your issues, just a possibility.

Nice animation!

Edited December 21, 2023 by Astronomist

[geoflewis]

John, that's a good animation, well done. Regarding you above 2 questions:-

1. That is the GRS. Be aware that many apps and planetarium software are not updated with accurate display of features on Jupiter's surface. IMO the best resource to look at is WinJupos, which has a graphic display and in my experience is far more accurate.
2. The old convention was South Up as that reflects how images were usually seen in old telescopes, but really there is no longer a 'correct' way. I used to display all mine South Up, but now usually go for North Up.

Edited December 21, 2023 by geoflewis

[Kon]

3 hours ago, John_D said:

called ASIStudio which is a much simpler tool than the other two but, other than not having an ROI featur

There is a ROI option under resolution.

In preferences have you checked the high speed usb traffic? It might not help with the usb 2 but worth trying.

[John_D]

1 hour ago, Astronomist said:

My frame rate sometimes drops from an already pathetic 18fps down to 3 or 4, I figured out recently that this was caused by the latop getting too cold. No idea if this is what is causing your issues, just a possibility.

Nice animation!

Thanks  Oddly enough I'd wondered if it was the temperature as well but I have managed to replicate some of the frame rate drops while testing indoors. However that doesn't preclude there being multiple problems! The author of AstroDMx ( Nicola ) has kindly investigated some of the issues that I was seeing but as they're intermittent and only seem to happen on my laptop then that's a software developer's worst nightmare. For now I'm chalking it up to an incompatibility somewhere in the myriad software libraries / hardware components in the laptop but I will keep testing to see if I can find a cause.

One further thought is that an SSD may help with the lower temperatures if you haven't already got one. It would certainly help with the speed of my laptop, along with upgrading the RAM!

[John_D]

2 hours ago, geoflewis said:

John, that's a good animation, well done. Regarding you above 2 questions:-

1. That is the GRS. Be aware that many apps and planetarium software are not updated with accurate display of features on Jupiter's surface. IMO the best resource to look at is WinJupos, which has a graphic display and in my experience is far more accurate.
2. The old convention was South Up as that reflects how images were usually seen in old telescopes, but really there is no longer a 'correct' way. I used to display all mine South Up, but now usually go for North Up.

Thanks  WinJupos was next on my list of things to investigate. It loads and seems to run OK under Wine on Linux.

[John_D]

19 minutes ago, Kon said:

There is a ROI option under resolution.

In preferences have you checked the high speed usb traffic? It might not help with the usb 2 but worth trying.

Ah, thank you. I'd seen the resolution drop down but not linked it with the "Move the position of ROI" symbol on the viewing area. I should have RTFM a little more carefully

I've fiddled with various USB settings but unfortunately it's not managed to fix the frame rate problem