H-alpha SHG from Oct 8 -- really quite good

[thesmiths]

Family commitments and the weather both allowed a nice spectroheliograph imaging session on Saturday morning. I am really liking the cool fall weather (not only for the less turbulent air, but I used to get sunburned in the summer). I have strategically positioned my mount to catch the sun as it passes between two roofs in between around 10:20am and 11:20am. I can set up up everything before that and then get three good data sets during that one hour viewing window. The three sets were a total of 270 GB. Today, the first one seems to have been the best (usually it's the last).

I was able this time to use the ZWO electronic focuser remotely and do all the image capture from indoors. This is quite a bit more comfortable, particularly as my desktop has a nice 1440p 27-inch monitor (and a mouse!).

Below is a stack of the best 17 frames from 26 SER files. The exposure was 2.0ms, gain zero, fps 290, scan rate 13x sidereal. I present here both the non-inverted and inverted versions of the same stacked image (using AS!3), and processing with ImPPG and Photoshop Elements. I quite like the inverted images for dramatic effect, and the prominences do seem to show up better.

Please click on the image to see at higher resolution. For full resolution, open in a new tab and click on various parts of the image with the magnifying icon.

H-alpha SHG: 106mm / 720mm APO refractor. 2400 l/mm grating. 9 micron wide chrome on fused quartz slit. ZWO 183MM camera. October 8, 09:25 UTC to 09:33 UTC.

081022-Ha-3-720mm-13x-stack-17-both.jpg (3.6 MiB) Viewed 1169 times

Despite having only a short window of opportunity to capture data, the overall result was very good. The atmospheric conditions were favourable and having done a similar imaging session of October 6, I knew how to organise my time. There was no time to do other wavelengths, as is possible during the summer months, but the Sun currently seems to have the most interesting features in H-alpha.

[Montana]

Stunning Douglas, absolutely stunning

Alexandra

[marktownley]

Couldn't agree more! Stunning work!

[GreatAttractor]

Stunning indeed. I thought it was a regular single-shot image through an etalon, had to double check the description.

[thesmiths]

I uploaded a video of one of the actual files that went into creating the H-alpha image from Oct 8. This is one of 26 scans acquired, of which 17 were processed in AS!3 to create a stacked image.

The original SER file was 3304 x 150 pixels and was acquired at 290 fps. The uploaded video is shown at 50 fps, so in effect is slowed down by about a factor of 6; this allows some of the fine details to be more easily discerned. The scan was done at 13x sidereal rate so it would take 120/13 = 9.2 sec to cross the solar disc (the video is about 1 min long).

If you look carefully, you can see prominences, particularly at the end of the video. The scan was done in DEC and the end of the video corresponds to south.

[Montana]

I loved that!!

Alexandra