Contains:  Solar system body or event
Full disk mosaic in hydrogen alpha on Sep 11th 2022, 



    
        

            Tommi Ropponen

Full disk mosaic in hydrogen alpha on Sep 11th 2022

Acquisition type: Lucky imaging
Full disk mosaic in hydrogen alpha on Sep 11th 2022, 



    
        

            Tommi Ropponen

Full disk mosaic in hydrogen alpha on Sep 11th 2022

Acquisition type: Lucky imaging

Acquisition details

Date: Sept. 11, 2022

Time: 10:01

Frames: 400

FPS: 160

Exposure per frame: 6 ms

Focal length: 3000

Seeing: 3

Transparency: 5

Resolution: 10949x5504

File size: 21.5 MB

Locations: Backyard, Espoo, Finland

Data source: Backyard

Description

This was slightly difficult set for post-processing to say the least. The final result is pretty OK considering that something happened to some of the original flats and I tracked the issue for days before I finally understood where the problem was. Luckily I have a new 12 core / 24 thread PC with 64 GB of ram and a decent GPU - it was really handy as I needed to stack the images several times with different flats and I built the mosaic too many times to remember. But yes, here is something that I hoped to achieve during this fall before the solar imaging season is over here in Finland. I was cutting it close as now, about a week later, temps are already low and its raining from day to day. 

In this particular image I put two different mosaic processing into one image as different aspect pop up a bit differently when the processing is changed. The end result is more than 10 000 pixels wide and between the "normal" (left) and "inverted" (right) image lies Earth showing the scale and it really is quite small in this context. All image processing was done with the help of Autostakkert3, ImPPG and Photoshop. These days the mosaic stiching in Photoshop works quite nicely although there is a multitude of different settings to explore in order to find the best for the case one is working with. I also tried to built the mosaic with PTGui, but at the end the Photoshop version looked better to my eyes. This is the colored version but I will also publish a black and white version as from that one sees some things again bit more differently than from these colored versions.

This season (from May to Sep) I did not get to image that much but I got some nice stills and animations and finally this mosaic with my portable grab & go, yet relatively high resolution setup. All in all the quality surpasses the quantity in my books and I think it might be time to take out fresh silica gel and pack my solar equipment until the spring of 2023.

Some details from the session: 
Each full disk mosaic consists of 53 separate frames (I took too many as I realized about half way in the session that I was looking the screen at 100 % zoom instead of just fitting the FOV to the laptop screen - thus the overlap of videos was much more than is actually needed). Each frame is a stack of 400 best images from a 20 sec video capture (a bit over 3200 frames per video). Total amount of data collected was 374 GB and total frame number somewhere south of 170 000. In each of these full disks there is thus 53 * 400 = 21 200 frames taken into account. Data was recorded with 6 ms exposure time and gain 125 in Firecapture (resulting in about 160 fps). Videos were taken within 35 minutes so this is not a "real" snapshot of the chromosphere as I would not record it for more than about 3 minutes in order to consider all movement frozen. The scale is around 0.39"/pixel with my setup (full size D-ERF + 102 mm FPL-51 doublet + Quark + ASI174mm on SolarQuest Alt-Az). In the beginning of the imaging session at 10:01 AM Finnish time the sun was about 23 degrees above horizon and at the end about 27 degrees above horizon. This caused also issues as the sun was getting brighter in a way that the histogram was shifted during the acquisition. I admit that while the result is not perfect it was most likely the most demanding h-alpha image processing quest for a while.

Comments

Revisions

  • Full disk mosaic in hydrogen alpha on Sep 11th 2022, 



    
        

            Tommi Ropponen
    Original
  • Final
    Full disk mosaic in hydrogen alpha on Sep 11th 2022, 



    
        

            Tommi Ropponen
    B

B

Title: Slightly better flatness

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Histogram

Full disk mosaic in hydrogen alpha on Sep 11th 2022, 



    
        

            Tommi Ropponen