A large dark filament 2018 08 27 280mm scope

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Valery
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A large dark filament 2018 08 27 280mm scope

Post by Valery » Tue Aug 28, 2018 1:55 am

Hi all,

Here is the image of a large dark filament I have captured early morning yesterday, August 27 2018.

Seeing was good for H-a and 280mm aperture. You can see all the finest details at the limit of 280mm aperture resolution and 0,2A single cavity etalon. Full size ARIES DERF was used in a front of th etelescope.

There were 4000frames stacked out of 4000frames recorded. ;)


Thanks for looking.


Valery
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2018-Auguest-27-05h-48m-280mm-ARIES-DERF-0,2A-Basler-1920-155.jpg
2018-Auguest-27-05h-48m-280mm-ARIES-DERF-0,2A-Basler-1920-155.jpg (495.87 KiB) Viewed 516 times
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.

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Re: A large dark filament 2018 08 27 280mm scope

Post by Carbon60 » Tue Aug 28, 2018 5:58 am

A very nice filament image, Valery.

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Re: A large dark filament 2018 08 27 280mm scope

Post by Valery » Tue Aug 28, 2018 9:43 am

TheSkyBurner wrote:
Tue Aug 28, 2018 2:05 am
How can you conclude that the pst etalon is .2@ without an ultrahigh resolution carey spectrometer?
1. It is not a PST etalon.

2. I have a solid etalon measured by the manufacturer at 0,25A. This one is condiderably more contrast and shows less double limb.
It also shows less double limb and a bit more cover the pebumbra than a 0,2A etalon in hands of another observer.
So, with a good portion of confidence I have concluded that this etalon is at least 0,2A. I personally believe that it is even a bit narrower.
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Re: A large dark filament 2018 08 27 280mm scope

Post by Montana » Tue Aug 28, 2018 11:15 am

A lovely shot Valery :bow
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Re: A large dark filament 2018 08 27 280mm scope

Post by Valery » Tue Aug 28, 2018 7:38 pm

TheSkyBurner wrote:
Tue Aug 28, 2018 5:33 pm
A: Oh i see! Well if you have a .025nm filter that you know was manufactured just for you, and running at that high of magnification it is way less than .2a

:)

B: I only ask because certain details seem to be missing for that narrow of bandwidth. You should inquire what F/ratio the filter was measured at by the manufacture. If the filter operates f/8 to be .025nm for example.

viewtopic.php?t=22979
The manufacturer of a 0,25A filter measured the bandwidth with their spectrometer and in the parallel beam.
In my scope it works at about F/45. My best filter outperforms this 0,25A without a doubts, while not much.

I also compared this 0,2A etalon against two air-spaced 0,7A double stacked. Close enough.

Valery
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Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.

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Re: A large dark filament 2018 08 27 280mm scope

Post by marktownley » Tue Aug 28, 2018 10:59 pm

TheSkyBurner wrote:
Tue Aug 28, 2018 10:19 pm
we are all curious what you are up to.
Yes we are!

Super shot Valery!
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Re: A large dark filament 2018 08 27 280mm scope

Post by Valery » Wed Aug 29, 2018 1:20 am

TheSkyBurner wrote:
Tue Aug 28, 2018 10:19 pm
is it a single filter or is it an fabyperot etalon? can you share a photo of it?

we are all curious what you are up to.
This is a mica based etalon.
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Re: A large dark filament 2018 08 27 280mm scope

Post by marktownley » Wed Aug 29, 2018 8:12 am

Solar spectrum?
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Re: A large dark filament 2018 08 27 280mm scope

Post by Valery » Wed Aug 29, 2018 9:08 am

marktownley wrote:
Wed Aug 29, 2018 8:12 am
Solar spectrum?
This is a DayStar Quark very carefully selected among too many samples to count. During two years. CWL uniformity just is not within +/- 0.05A. With a neutral gamma setting the unifomity of 90%+ of filter aperture is very good flat. Only with contrast rised to a high enough gamma, I can see some smooth brightness variations. Visually this sample beats (hands down) any single stack etalon include carefully selected PST etalon (which shows equal pictures with 0.3A mica based etalons from both main manufacturers). For visual observations I really do not need a DS. No need a DS when image the Sun on 80% of the disk and promineces. Only near the limb I feel I need a DS.
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.

Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.

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Re: A large dark filament 2018 08 27 280mm scope

Post by krakatoa1883 » Thu Aug 30, 2018 4:58 pm

Looks impressive.... how did you calculate resolution ?
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Re: A large dark filament 2018 08 27 280mm scope

Post by Valery » Mon Sep 03, 2018 12:24 pm

krakatoa1883 wrote:
Thu Aug 30, 2018 4:58 pm
Looks impressive.... how did you calculate resolution ?
It is easy. I know the FL, I know the scale arc sec per pixel, I know the smallest details resolved. Compare it with theoretical resolution.
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.

Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.

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