Contains:  Solar system body or event
Half a sun hydrogen alpha mosaic on July 8th 2022, 


            Tommi Ropponen

Half a sun hydrogen alpha mosaic on July 8th 2022

Acquisition type: Lucky imaging
Half a sun hydrogen alpha mosaic on July 8th 2022, 


            Tommi Ropponen

Half a sun hydrogen alpha mosaic on July 8th 2022

Acquisition type: Lucky imaging

Acquisition details

Date: July 8, 2022

Time: 10:37

Frames: 400

FPS: 162

Exposure per frame: 5.50 ms

Focal length: 3075

Seeing: 4

Transparency: 7

Resolution: 11708x5000

File size: 17.8 MB

Locations: Backyard, Espoo, Finland

Data source: Backyard


I took the data while suffering from a flu which is typical since this day was the first day of my summer vacation - of course it starts with a flu! So I crouched under a black tarp in order to see something on the laptop screen while in direct sunlight and heard my 3.5 year old son playing at the sand box with her mom and grandmother. I had hard time to decide which processing shows all features as typically one type of processing just don't cut it. So I ended up showing both black and white and and false colored images with normal and inverted processing. One can choose between those to see which phenomena one wants to look at.

This was imaged between 07:37 and 07:53 UTC on July 8th in Finland from our apartment building asphalt parking lot. Luckily the day was not very hot and the local time while starting the session was 10:37 so the asphalt was not yet too hot to cause severe image degradation. In the afternoon I usually do not image at all due to strong heat flux from the ground.

This is a mosaic combined from stacked images from 26 videos. For these half sun mosaics I collected 184 GB of SER video at 162 fps. Each video was recorded for 20 seconds resulting around 3200 frames with 5.5 ms exposure time and gain of 125 in Firecapture. Then I stacked best 400 frames for each video, processed images in ImPPG (deconvolution with normal and inverted processing) and combined the mosaic and adjusted the final touch (including false colorization) in Photoshop. Both inverted and normal image are shown as some features are more easily seen from another while others from the other type of processing. I also like to put all of the processings into one collage as one can easily compare views and see those solar features quickly between different processings without changing photos on the screen. Luckily I have dialed my post-processing flow to a pretty good level so I did not need to blow my mind in post-processing while suffering the flu. It has took some time for me to figure out my preferred workflow but luckily it still is not as heavy as DSO processing (which I know nothing about, I am just reflecting what I have heard).

The total imaging time (time elapsed between the first and last video) was about 16 minutes. So while not fully optimal (one can see movement in the solar hydrogen plasma easily within a few minutes with this image scale) I decided to try this mosaic. The scale in my imaging setup is around 0.39"/pix. I use a cheap alt-az mount (SkyWatcher SolarQuest) and adjust the view via the mount's manually controlled built-in joystick-based drive system. Not optimal, but it still seems to work while I am over the recommended weight limit for the mount. For Grab & go one really cannot get a lighter setup for hydrogen alpha showing details at this level so I am really happy about the setup.

The results look quite nice even as mosaics. One can see several active areas and sunspots, filaments on the solar disk reaching towards the solar limb and prominences on the solar limb. Image of the Earth is added to show the scale compared to the size of the sun. Next time, while understanding that it is not gonna be a snapshot of the solar structures as it is, I might try to get a full disk mosaic of our nearest star even if it takes 25 - 30 minutes to gather all the data (maybe a bit less if I take a risk and use less overlap between videos).

Now as the vacation has started I hope there will be clear skies to do some more solar imaging!