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FDs & G-Band images (New G-Band Animation added)

Posted: Sat Dec 16, 2017 7:36 am
by yltansg
Hi everyone,

Greetings from Singapore. It has been raining and cloudy for quite a while. I am glad to have 30 minutes this morning with thin layer of clouds over the Sun to get this 3 full disks. Generally a blank disk on WL and some filaments and prominences on HA and interesting areas of magnetic field concentration in the CAK image.

Image

Alfred

Re: Full disks in 3 wavelengths and scopes used

Posted: Sat Dec 16, 2017 2:49 pm
by ffellah
A beautiful set, Alfred. I am glad you had some sun after a long time.

Franco

Re: Full disks in 3 wavelengths and scopes used

Posted: Sat Dec 16, 2017 2:57 pm
by eroel
Alfred:
Beautiful 3 flavor session.
Best regards,
Eric.

Re: Full disks in 3 wavelengths and scopes used

Posted: Sat Dec 16, 2017 11:11 pm
by MapleRidge
Those are very sharp Alfred...well done :bow

Brian

Re: Full disks in 3 wavelengths and scopes used

Posted: Sun Dec 17, 2017 7:11 am
by Carbon60
A very fine tryptic, Alfred.

Stu.

Re: Full disks in 3 wavelengths and scopes used

Posted: Sun Dec 17, 2017 8:40 am
by marktownley
Three very nice disks Alfred!

Re: Full disks in 3 wavelengths and scopes used

Posted: Sun Dec 17, 2017 1:39 pm
by yltansg
Thanks Mark, Stu, Brian, Eric and Franco. Seeing condition continue to be poor today. I took 2 more scopes out of cold storage. These were the images from today's session.

For H-Alpha imaging, a150mm refractor with ARIES D-ERF and Lunt 50.
Image

This was the best of 3 H-Alpha images taken this morning (17 Dec 17)
Image

For G-Band imaging, I used an ARIES C8 ERF with a 430nm filter
Image

It was a struggle to get a decent G-Band image this morning.
Image

This was taken on 1 Nov 17 with the same setup when the seeing was better.
Image

Re: FDs, G-Band images and Scopes (New images added)

Posted: Sun Dec 17, 2017 7:44 pm
by marktownley
Good additions! Seeing makes all the difference!

Re: FDs, G-Band images and Scopes (New images added)

Posted: Mon Dec 18, 2017 6:42 am
by Derek Klepp
Thanks Alfred and good to see the comparison in seeing conditions.

Re: FDs, G-Band images and Scopes (New images added)

Posted: Mon Dec 18, 2017 12:35 pm
by Montana
A lovely traffic light! and the close ups are fab but the 1st Nov is the business :bow :hamster:
Alexandra

Re: FDs, G-Band images and Scopes (New images added)

Posted: Mon Dec 18, 2017 12:46 pm
by ffellah
That granulation is amazing, Alfred. Well done !

Franco

Re: FDs & G-Band images (New G-Band animation added)

Posted: Mon Dec 18, 2017 2:08 pm
by yltansg
Thanks Mark, Derek, Alexandra and Franco for your kind comments. Here is a time-lapse gif made from 12 stills taken on 6 Oct 17 from 7:58am to 8:06 am local time.

Image

Enjoy it.

Alfred

Re: FDs & G-Band images (New G-Band Animation added)

Posted: Tue Dec 19, 2017 2:45 pm
by pedro
Great HR (granulation) images there Alfred, well done

Re: FDs & G-Band images (New G-Band Animation added)

Posted: Wed Dec 20, 2017 7:29 am
by yltansg
pedro wrote: Tue Dec 19, 2017 2:45 pm Great HR (granulation) images there Alfred, well done
Thanks Pedro. I am able to get reasonable G-Band images with the Edmund Optics 25mm 430/10nm filter when the seeing is average and better. However I have not been able to get a decent image with the Baader Calcium K-Line Filter. I have been trying for some months now :( Most of the time I used the 430/10nm first and the seeing became poor by the timing I changed over to the K-line filter. Will share findings.

Alfred

Re: FDs & G-Band images (New G-Band Animation added)

Posted: Mon Dec 25, 2017 4:15 pm
by christian viladrich
Hello,

The G-band image taken on Nov 1st is pretty good. Well done !

There is no wonder that you get unsatisfactory K line images with the C8. The spherical aberration is so large in near UV that the instrument is no longer diffraction limited.
Image
In the whole, and for diameters larger than around 150 mm, a G-band filter gives images more satisfactory images than a K-line filter:
- the contrast is about the same,
- the sensitivity to turbulence is lower,
- most optics are much better at 430 nm than at 396 nm.
BTW, what is you exposure time with your 430nm FWHM 10 nm filter and the C8 ?
Best regards
Christian

Re: FDs & G-Band images (New G-Band Animation added)

Posted: Thu Dec 28, 2017 2:24 pm
by yltansg
christian viladrich wrote: Mon Dec 25, 2017 4:15 pm
In the whole, and for diameters larger than around 150 mm, a G-band filter gives images more satisfactory images than a K-line filter:
- the contrast is about the same,
- the sensitivity to turbulence is lower,
- most optics are much better at 430 nm than at 396 nm.
BTW, what is you exposure time with your 430nm FWHM 10 nm filter and the C8 ?
Best regards
Christian
Hi Christian,

Thanks for the valuable information. I am still hoping to catch a nice K-Line image when there is very good seeing :)

The following are the setting for the 1 Nov G-Band image:
FPS (avg.)=151 Shutter=0.082ms Gain=92 (23%)
Histogramm(min)=84 Histogramm(max)=148 Histogramm=58%

Alfred