One of the things that I’ve been wanting to do is to create an animation of Jupiter’s great red spot traveling across the face over the course of a few hours. I had some ideas as to how to accomplish that, but wasn’t sure exactly how to work it out. I settled on a method. Time will tell if there is an easier way.
The first thing to determine is when the GRS will transit the planet. Jupiter rotates in roughly 10 hours at that latitude, so there are plenty of chances to catch it. It isn’t too hard to wait a day or two until the transit occurs at a reasonable time during the night. One thing to keep in mind; there are a number of web pages that tell you when the transit will occur. In many cases, the time that it quotes will be the moment when the GRS is half-way thru its journey. So, if you want to capture a complete trip across, you will need to start taking photos a while earlier. Probably around an hour earlier.
I prefer to use an app on my phone from Sky and Telescope called “Jupiter’s Moons”. It will show not only the moons, but their shadows, along with the GRS. It’s handy.
Once you know the right time, get yourself set up as far in advance as you can. It’s nice if you can fine tune your tracking to get it as smooth as possible.
Here is the setup I use:
- Celestron 9.25
- CGEM Mount
- ZWO ASI120MC-S
I also use a Canon T6i, but I decided not to use it in this instance. Using the 120MC I can both guide and photograph with the same camera. This makes the process much easier. Also, FireCapture is very well suited to this task. It allows capture, wait, capture, etc.
Here is an overview of the steps I take to arrive at this goal.
- Get Jupiter in view and focused in the camera.
- Decide on the appropriate exposure time and other image settings. I used 1000 frames at iso 400 and 1/20th of a second.
- Set up the autorun feature on FireCapture, so that you can take a video, wait some period of time, and then take another video.
- I captured the 1000 frames, waited 5 minutes, and then repeated. I did this for about 3.5 hours. This was not long enough to capture a full trip across, but it did around 2/3rds.
- Once the capturing was done. I started stacking. I did this in Registax. It has the ability to create groups of files to stack, so you can set that up and walk away. You can also do some post processing automatically in Registax. I’ll explore that in a later blog entry.
- Once I was satisfied with all of the stacked images, it was time to organze them into an animated gif. I did this with Gimp. You can import a group of images into layers in Gimp. I did this, and then aligned all of the layers so that the image of Jupiter was in exactly the same place in each layer. Then Gimp will export the layers as an animated gif.
The result is below. It’s not at all perfect, but I’m pleased with this initial result. I should probably try this again before Jupiter is too far along in the season to watch for 4 hours.