Analemma Solar

[Aripaule]

Hello!
I was thinking that it might be cool to have a function or module that would be able to record a solar analemma.

I believe that allky ​​already meets several requirements, such as:

1. remaining static in place 365 days a year.

2. being available every day, during the same time;

3. having the ability to save these images, organized by date for later stacking.

Would that be possible

?

Thanks and see you later!

[EricClaeys]

It would be possible - it just needs someone to write the code.
Someone also asked for the ability to have a keogram based on a single picture every day. Both these requests would require images from every day of the year - one from daytime and one from nighttime.
We currently have a very long backlog of features we'd like to implement. If you, or someone you know could help develop the feature that would be great.

[c40415]

Hello.
I just installed my allsky camera. So far it's been working great, the documentation is clear and helped me to do many thing (remote website, gathering data from DHT11 and from an ADC to print it on the live view...) So first thing first: thanks to all the team for that!

Next, the idea of doing an analemma crossed my mind. I'm using a ASI120MC camera with its original lens. With the automatic setup in daylight, the Sun makes a whole area saturated, pretty useless for tracing analemma.

I'd like to try to write a module for this purpose. It would need to trigger a super short exposure at a definite time of the day, to see the exact position of the Sun.
The old documentation seems to have a ./capture.sh program with arguments.
https://www.instructables.com/Wireless-All-Sky-Camera/

tl;dr: how can I trigger capture from custom script?

[c40415]

Self answering my question: the program is called capture_ZWO and is located in ~/allsky/bin
I'm back in business, will post future progress.

[EricClaeys]

Note that only 1 program can have the ZWO camera open at a time, so if you're running Allsky 24 x 7, no other program can use the camera.
You could have a program to do what you want, but it'll be a lot of work.

capture_ZWO currently has no way to stop after one image. The program could look for a new image, and once found, stop capture_ZWO.

The program would need to stop Allsky at a certain time, run capture_ZWO with a short manual exposure, then save the image to some directory.
You'd probably want to temporarily turn off "save image" so you don't end up with a single dark image in a timelapse.

There are a lot of details that would need to be worked out.

[c40415]

Thanks for your insight.

I played a little bit with capture_ZWO yesterday and as you said, there's many things to be worked out.
For instance I run ./capture_ZWO -cameramodel ASI120MC-S -latitude 48.58 -longitude 7.71 -type 1 -dayexposure 64 -daygain 0 -filename analemma.png and ended up with

which is quite deceiving from a saturation standpoint. I'll try with the camera plugged to my computer with ASI capture, to confirm this is lowest brightness I can get with my setup. The minimum exposure time supported by this camera is 64µs.

I noticed capture_ZWO doesn't stop taking picture, it stopped the regular allsky session, but after I ctrl-C the program in my bash, the regular allsky session restarted with very few messed up parameters, which is fine.

About the general architecture of the project, I rely on your expertise. As I understand, a python module would be impossible. One would need to rewrite allsky to integrate this feature?

[EricClaeys]

All exposure times are stored as milliseconds, not microseconds, so your "64" is 64 milliseconds. Try lowering the number.

FYI, when Allsky starts it puts most of the settings in ~/allsky/tmp/capture_args.txt. It then calls

capture_ZWO -debuglevel ABC -cameramodel ASI120MC-S -cameranumber 0 -locale DEF -config ~/allsky/tmp/capture_args.txt

(replace ABC with your debug level, and DEF with your locale).
Try running ALlsky, then run ps -ef | grep capture_ZWO to see what the exact command line is. You can create your own "capture_args.txt", modify as desired, and pass it to capture_ZWO.

Re: I noticed capture_ZWO doesn't stop taking picture
Right, I mentioned earlier that capture_ZWO can't only take 1 image. I can add an option you could pass to it to limit the number of images to 1 (or any number you want).

What would the Python module do?

Before you go further, I suggest you upgraded to the newest version (which is in test mode); any changes I might make to help would be done in that version.
To do so, do a "normal" upgrade, but use the following for the "git clone ..." command:

git clone --depth=1 --recursive --branch v2025.xx.xx https://github.com/AllskyTeam/allsky.git

[c40415]

Great! I'll try your suggestions during the following day, fingers crossed it won't be too cloudy.

exposure times are stored as milliseconds, not microseconds

My mistake came from: capture_ZWO --help it says : -dayexposure n - Daytime exposure in us [300000].
Didn't update yet (see below).

I can add an option you could pass to it to limit the number of images to 1 (or any number you want).

That would be great!

What would the Python module do?

I may be thinking way ahead here: it would be nice for other users to simply have this feature as a module. First parameter that would come to mind is the UTC time to run capture. Maybe a JPG/PNG option.

As you recommended I run the upgrade command but ended up with

fatal: destination path 'allsky' already exists and is not an empty directory.

[EricClaeys]

For the upgrade, run:

cd
sudo systemctl stop allsky 
mv allsky allsky-OLD 
# run the "git clone" command from above
cd allsky 
./install.sh   #  make sure you tell it to use the prior Allsky 

I will look into the other items.

[EricClaeys]

I added a "maximages" argument to the capture program. To get it, once you upgrade to v2025.xx.xx and it's working, run:

cd ~/allsky
./upgrade.sh --skip      # Pick the "Replace All" method

It will rename your prior allsky (which was in "allsky-OLD") to "allsky-OLDEST". You may want to rename allsky-OLDEST to something like "allsky-v2024" in case you ever need to go back to it.

To use the new argument, add -maximages 1 to the capture_ZWO command line.
Let me know how it goes.

[EricClaeys]

Forgot to mention, the "us" versus "ms" is also fixed. Internally, the capture programs use "us" but the user enters in "ms".

[EricClaeys]

@Aripaule,
Do you want the single image you're creating manually to have the overlay put on?

[EricClaeys]

@Aripaule,
I just made a change.

capture_ZWO saves an image in allsky/tmp/current_images/image-YYYYMMDDHHMMSS.jpg.
It then normally calls saveImage.sh to process that image (including adding an overlay), copy it to allsky/images/YYYYMMDD, then rename it in the tmp directory to image.jpg.
If you set the "maximages" to a NEGATIVE number, like -1, capture_ZWO won't call saveImage.sh so the image won't be permanently saved or uploaded, nor will it have an overlay added.

Further, if you change the save_dir argument in the "capture_args.txt" file you call tell capture_ZWO where to put the file. Assuming you have a directory per year, you'd save it there.

Your script would need to:

• stop Allsky
• modify "capture_args.txt" (or whatever config file you use):
  • set "dayexposure" to a small number
  • set "dayautoexposure=false"
  • set "save_dir" to your directory
  • If you want a .png file, set "filename=image.png"
  • set "maximages=-1" # or "1"
• run capture_ZWO pointing to your configuration file
• As needed, move the image-YYYYMMDDHHMMSS.jpg file
• restart Allsky

I'm sure I missed some things.
"sed -i" would be good for modifying the capture_args.txt file.

[c40415]

I tried a few things. I made a analemma_args file (attached) to makes the whole process easier.
analemma_args.txt
with this command ./allsky/bin/capture_ZWO -debuglevel 1 -cameramodel ASI120MC-S -cameranumber 0 -locale en_GB.UTF-8 -config ~/allsky/analemma_args.txt I get the image bellow.

As you can see in the arguments, I'd like to have a PNG file for later stacking all these shots, but I end up with a jpg (my guess would be it is caused by the overlay process?)

Note: I tried the first test with allsky running, some shot were fine, but I ended up with errors like

capture_ZWO: ERROR: mismatch with number of ZWO cameras connected: per ZWO SDK: 0, per /home/clovis/allsky/config/connected_cameras.txt: 1
Attached Cameras:
***** Stopping Allsky (code 100) *****
And the only way to fix this would be to reboot the pi.
Therefore I took as a habit to do sudo systemctl stop allsky / analemma capture / sudo systemctl start allsky

It's looking great so far, the maximage argument is quite handy, thank you.
I didn't find how to impeach capture_ZWO to apply the overlay.
EDIT: I read the reply to Aripaule, I'm back on track.
My intention is to make a python script to manage all these steps. How would you recommend to trigger this script at a definite time, let's say 13h00 UTC?

[EricClaeys]

As I mentioned earlier, you can't run capture_ZWO when Allsky is running.

If you set maximages to -1 it won't add an overlay, which I'd assume is what you want. It might also create a .png file; you would have to check.

Look at adding a periodic module in the Module Manager.

[Alex-developer]

My intention is to make a python script to manage all these steps. How would you recommend to trigger this script at a definite time, let's say 13h00 UTC?

The best way to handle this would be a standalone script that run on crond

You cannot do this in a module in Allsky since stopping Allsky would stop all of the flows and kill the process.

if you get your script running we can help get it running thru crond but its something along the lines of

crontab -e

At the bottom add

0 13 * * * /home/pi/thescript.sh

That will run it at 13:00 every day

Alex

[c40415]

Thanks for your help! I'm learning so much from this project.

I made this script
analemma.sh
and this config file
analemma_args.txt
which are running fine from bash.

I end up with this raw picture, which need a little boost from siril.

As you can see, weather is not on my side.

Then I struggled to make it work from the module manager. The test button returned an error.

I tried running the script from /allsky/config/myFiles/modules/ but it didn't help.
Plus this dialog doesn't let you define a time of the day, so your solution comes at the right time (no pun intended).

[EricClaeys]

Per Alex's reply, the Module Manager won't work and you'll need to use a "cron" job.