Sunspots, in "white...
 
Notifications
Clear all

Sunspots, in "white light"

6 Posts
3 Users
4 Likes
131 Views
Paul Walker
(@pwalker)
Trusted Member Admin
Joined: 10 years ago
Posts: 59
Topic starter  

I received a text and email at 6:08 PM EDT alerting me to a solar flare that had been detect at 5:48 PM (M2.8 class solar flare at 14-Jul-2022 at 21:48:00 UTC).

10 minutes after the notice (30 minutes after the detection) I took the image below. I may or may not have gotten a picture of the flare. The 2 largest sunspots have light colored areas in the dark umbra region. I don't know whether it was one of those 2 or one of the smaller sunspot groups that produced the flare. I'm guessing it was the large spot to the lower right. I also don't know whether it was bright enough to see in white light (as opposed to Terri's H-alpha images) nor whether if it was visible whether it was still visible when I took the image.

2022-07-14  6:18 PM EDT
10in F/4 (1000mm fl) stopped down to 8" f/5 (due to using an 8" full aperture filter @ prime focus, 1/1250s @ iso200, Canon Rebel T7i camera with Baader coma corrector. Processing notes: crv-unshpR2,R2,R4-cb-cropped67%

Full resolution, cropped by 67%

 


   
Quote
Terri Zittritsch
(@terri)
Member - Treasurer
Joined: 3 years ago
Posts: 165
 

Nice image Paul!   I like the 'clean-ness' of white light solar images.       I missed yesterdays imaging and could kick myself.  I was thinking of setting up right after work, and thought i'd go for a bike ride instead, and ended up doing neither. 🙁     What app do you use for solar flare alerts?

 

Terri


   
ReplyQuote
Paul Walker
(@pwalker)
Trusted Member Admin
Joined: 10 years ago
Posts: 59
Topic starter  

Thanks Terri.

I signed up for alerts on https://www.spaceweatheralerts.com/.   It costs $50/yr but you can suspend or cancel any time.  They send both email and text notices.


   
ReplyQuote
Paul Walker
(@pwalker)
Trusted Member Admin
Joined: 10 years ago
Posts: 59
Topic starter  

Here's a picture of the Sun with sunspots taken yesterday, Saturday, Sept. 2, 2022 from my backyard.
I continue to be surprised and pleased with the amount of detail I can see visually and image on the better days. The day before, Friday, was a day with poor seeing. Visually I have been using an 8" f/6 Orion SkyQuest Dobsonian telescope with a full aperture Orion glass solar filter. For imaging I have been using my 10" f/5.6 Newtonian with an 8" Baader ASTF 200 solar film filter which stops it down to f/7.
The images below are contrast enhanced using a histogram stretch (curves tool) and sharpened (using an unsharp mask tool).

10inF5.6, Canon T7i camera @ prime focus.
With Baader ASTF 200 (8") solar film filter.
1/800 sec @ iso 100

 
Here's a crop from the above full disk image.
On this image the smallest, medium to high contrast features, appear 2-3 pixels across.
At the camera's resolution of 0.52" (arc sec) per pixel this is 1" to 1.5" across for these features.
 
 
I also took images using a Barlow lens which gives me 2X the magnification of the prime focus shot. Here's a crop from that image.
This and the prime focus image were picked as being the best of 51 and 42 images taken respectively.
On this image the smallest, medium to high contrast features, that are visible on both images appear 3-4 pixels across.
At the camera's resolution of 0.26" (arc sec) per pixel with this setup this is 0.75" to 1.0" across for these features. This is closer to the actual resolution. This shows that the prime focus image in this case actually blurs and broadens the features slightly.
The images were taken 10 minutes apart so most the the visual differences are do to atmospheric distortion.
To give an idea of size:
Sun's mean diameter is 865,370 mi = ~30' (1800") of arc. So 1 arc sec (1") on the Sun = 480 miles.
This sunspot group spans about 470" which is ~225,000 miles, the distance from here to the Moon (ranges from 221,000 to 253,00 miles).
 
This post was modified 3 months ago 2 times by Paul Walker

   
ReplyQuote
Terri Zittritsch
(@terri)
Member - Treasurer
Joined: 3 years ago
Posts: 165
 

Nice additions Paul.   Great detail.. some nice deep shots.

 

 

Terri


   
ReplyQuote
Greg Erianne
(@greg-erianne)
Estimable Member
Joined: 1 year ago
Posts: 94
 

Great images, Paul!  Geez, the size of those sunspots is absolutely amazing.  

I was waiting for the USPS to deliver a solar filter today, but was absolutely shocked when it didn't arrive -- NOT!  Would have liked to take a few shots myself.

Beautiful images...

Greg  


   
ReplyQuote
Share:
Share on...