April Solar Challenge

[LeoD]

Great, very well balanced image!
I took the liberty... sorry, Mark, I have to geek out.
what do you think?

[Carbon60]

Light Bridges in CaK

20220423_CaK_Light Bridges by Stuart Green, on Flickr

Stu

[DeepSolar64]

Beautiful work Stu!!

[steveward53]

This month let's look closer at the penumbra and umbra of sunspots in white light (or Calcium II K).

We have to be really careful when imaging the umbra that you don't capture at too low a gamma, or do to much drastic contrast enhancements that you lose the detail in the what you think is black umbra. Remember that the umbra only looks black against the very bright surface of the Sun but it is in fact quite bright and holds a host of interesting features.

Alexandra

Hi Alexandra,

This is my biggest gripe with NASA/SDO.

I check the SDO/HMI Quick-Look Continuum page every morning (as do many others I suspect) just to see what's appeared
overnight and awaits capture.

The resolution is superb as you'd expect from a 4096x4096 sensor and the location , but the people/person processing the data always has the black-point shoved up way too close in my opinion and it destroys any hope of making out any detail in the umbra and exaggerates the limb darkening to such an extent that any brand new arrivals (or departing regions) get lost in the dark earlier than is necessary.

https://sdo.gsfc.nasa.gov/assets/img/la ... 6_HMII.jpg

I am as careful as I can be when playing with my meagre data to not kill of any umbral details my humble set-up may have captured .

I e-mailed them regarding this many moons ago but sadly got no response.

Regards ,

Steve.

[DeepSolar64]

This month let's look closer at the penumbra and umbra of sunspots in white light (or Calcium II K).

We have to be really careful when imaging the umbra that you don't capture at too low a gamma, or do to much drastic contrast enhancements that you lose the detail in the what you think is black umbra. Remember that the umbra only looks black against the very bright surface of the Sun but it is in fact quite bright and holds a host of interesting features.

Alexandra

Hi Alexandra,

This is my biggest gripe with NASA/SDO.

I check the SDO/HMI Quick-Look Continuum page every morning (as do many others I suspect) just to see what's appeared
overnight and awaits capture.

The resolution is superb as you'd expect from a 4096x4096 sensor and the location , but the people/person processing the data always has the black-point shoved up way too close in my opinion and it destroys any hope of making out any detail in the umbra and exaggerates the limb darkening to such an extent that any brand new arrivals (or departing regions) get lost in the dark earlier than is necessary.

https://sdo.gsfc.nasa.gov/assets/img/la ... 6_HMII.jpg

I am as careful as I can be when playing with my meagre data to not kill of any umbral details my humble set-up may have captured .

I e-mailed them regarding this many moons ago but sadly got no response.

Regards ,

Steve.

Steve,
Try this site. https://suntoday.lmsal.com/suntoday/?su ... 2022-09-03 These images show more balanced detail than many. I really like their 4K white light images. They look even better if you sharpen them just a little in GIMP, PhotoShop etc.

The images appear quite natural and there is no exaggerated limb darkening. Umbral and penumbral detail is decent too.

James

SDOHMIc_Greyscale4K_9-2-22.jpg (3.35 MiB) Viewed 970 times

I use this site a lot too.

https://www.thesuntoday.org/sun/current-observations/

[steveward53]

"Steve,

Try this site. https://suntoday.lmsal.com/suntoday/?su ... 2022-09-03 These images show more balanced detail than many. I really like their 4K white light images. They look even better if you sharpen them just a little in GIMP, PhotoShop etc.

The images appear quite natural and there is no exaggerated limb darkening. Umbral and penumbral detail is decent too.

James"



SDOHMIc_Greyscale4K_9-2-22.jpg


Thank you James ,

Seems silly that an outside party has to reprocess the data "properly" , but I suppose if I'm the only person who's complained then NASA has better things to worry about right now.

[DeepSolar64]

Steve,
I agree with you. They should be processed properly. I use these images as observational guides at the scope with a computer set up or on my smartphone. I look at what is there and try to see it in the scope. So the image needs to be accurate. I use the NSO GONG Ha images in the same way.

And you are welcome.

James

[steveward53]

Steve,
I agree with you. They should be processed properly. I use these images as observational guides at the scope with a computer set up or on my smartphone. I look at what is there and try to see it in the scope. So the image needs to be accurate. I use the NSO GONG Ha images in the same way.

And you are welcome.

James

I know only too well how tricky it can be to try and get some sort of consistency in images on a day to day basis .

But the folks at NASA/SDO don't have to contend with seeing issues , contrails , haze , clouds , smoke , Saharan dust .... etc etc ...

I assume it's just been set-up and runs automatically , I will try contacting them again though just to remind them ...


Anyway , must dash , time for a big mug of coffee and get set up , Sun will be appearing in 30 minutes and I've got a new camera to aim at it ...

[DeepSolar64]

Good luck Steve. I have been under mostly cloudy skies and have gotten only a quick 8x32 solar binocular view.