The Official Imaging the Sun Thread

Wow! Amazing pics from both of you!

MalVeauX wrote in post #18857989
May 7th 2019,

Looking deep into AR2740 in red wavelength. Red allows you to see deeper into the spot and find structures, as there's generally shallow structures and the deeper black core where temperatures are much cooler than the surrounding structure as magnetic fields whirl around it with material flinging all around the lines. Presented in white light for the photosphere, hydrogen alpha & calcium K for the chromosphere from an 8" F21 solar scope. Small scales provided of both AR2740 & AR2741 from an 80mm F21 solar scope.

IMAGE LINK: https://flic.kr/p/2eqT​7Ya

IMAGE LINK: https://flic.kr/p/S4m3​WR

IMAGE LINK: https://flic.kr/p/2fPQ​Yuv

IMAGE LINK: https://flic.kr/p/TFA7​hN

https://flic.kr/p/S4kZ​LT

https://flic.kr/p/S4kY​Pn

https://flic.kr/p/S4m1​JV

https://flic.kr/p/2eC6​UWw

Very best,

Excellent series Martin and thanks for the write up on the various filters used and wavelengths observed.

Have you had any experience with the Baader Solar Continuum Filters? It looks like they operate at 540nm.

Cheers

Dennis

nardes wrote in post #18858034
Have you had any experience with the Baader Solar Continuum Filters? It looks like they operate at 540nm.

Dennis

Hi Dennis,

Yessir, the solar continuum filter is around sodium line which is 588~589nm, and the continuum is 540nm (+/- 10nm bandpass). This is a great wavelength for general continuum (photosphere) imaging because almost every optic is designed around correction in the green wavelengths as that's the most sensitive to human eyes, so naturally, we make optics that correct and transmit these wavelengths best (and by comparison, we don't put much into visual instruments for correction in invisible to us wavelengths, like near UV and longer IR). 540nm wavelength is a shorter wavelength than 656nm (Ha) and has a higher angular resolution, so you can resolve detail in the photosphere a bit better at this wavelength. That said, the shorter the wavelength, the more challenging the seeing becomes. But 540nm isn't that bad, it's pretty nominal. Under really poor seeing, going long wavelength and narrowband is ideal (such as 656nm but loose bandwidth, such as 656 +/-12nm HA filter that will show the photosphere but not be sub-angstrom, eliminating all other wavelengths and steadying the seeing). Even higher resolution would be 430nm, or G-band, there are unique features at this wavelength in the photoshpere, specifically between the convection cells, you'll see tiny bits of bright spots that are Iron, but they're visible at this wavelength unlike others. And to go even higher angular resolution is to go to 393nm, which is the calcium line. Loose enough bandwidth (such as the baader k-line filter) is basically a UV filter and will have high contrast and very high angular resolution, but it is very difficult to image with, and most instruments are not well corrected at this wavelength so some are not diffraction limited and will not have sharp focus, etc. If the bandwidth at 393nm is sufficiently narrow, around 5A (angstrom) you begin to see the chromosphere as the photosphere is largely blocked out, and you start to see the ionized calcium around the faculae and magnetic activity regions.

So basically:

540nm - Great all around wavelength when seeing is good for photosphere imaging. Baader Solar continuum filter (540nm +/- 10nm).
656nm - Great long wavelength for when seeing is poor and if you want to see more detail inside of a large sunspot. Astronomik 12nm Ha filter (656nm +/- 12nm).
430nm - Excellent for photosphere imaging with very high contrast and higher angular resolution. Andover surpluss G-band filter (430nm +/- 2nm).
393nm - Excellent for photosphere imaging, also with high contrast and even higher angular resolution, but darker inside of sunspots. Baader K-line filter (395nm +/- 8nm).

Alternatives to Gband & Calcium, you can go around 500nm where OIII narrowband filters are for a similar look (501nm, +/- 10nm) on instruments such as SCT or other mirrors that are poorly corrected for near UV wavelengths. They tend to bottom out around 500nm or so. Good newtonian mirrors, F5 and longer, are fine. And most refractors are of course fine for this (no APO needed when you're focusing a single wavelength of light).

Very best,

MalVeauX wrote in post #18858051
Hi Dennis,

Yessir, the solar continuum filter is around sodium line which is 588~589nm, and the continuum is 540nm (+/- 10nm bandpass). This is a great wavelength for general continuum (photosphere) imaging because almost every optic is designed around correction in the green wavelengths as that's the most sensitive to human eyes, so naturally, we make optics that correct and transmit these wavelengths best (and by comparison, we don't put much into visual instruments for correction in invisible to us wavelengths, like near UV and longer IR). 540nm wavelength is a shorter wavelength than 656nm (Ha) and has a higher angular resolution, so you can resolve detail in the photosphere a bit better at this wavelength. That said, the shorter the wavelength, the more challenging the seeing becomes. But 540nm isn't that bad, it's pretty nominal. Under really poor seeing, going long wavelength and narrowband is ideal (such as 656nm but loose bandwidth, such as 656 +/-12nm HA filter that will show the photosphere but not be sub-angstrom, eliminating all other wavelengths and steadying the seeing). Even higher resolution would be 430nm, or G-band, there are unique features at this wavelength in the photoshpere, specifically between the convection cells, you'll see tiny bits of bright spots that are Iron, but they're visible at this wavelength unlike others. And to go even higher angular resolution is to go to 393nm, which is the calcium line. Loose enough bandwidth (such as the baader k-line filter) is basically a UV filter and will have high contrast and very high angular resolution, but it is very difficult to image with, and most instruments are not well corrected at this wavelength so some are not diffraction limited and will not have sharp focus, etc. If the bandwidth at 393nm is sufficiently narrow, around 5A (angstrom) you begin to see the chromosphere as the photosphere is largely blocked out, and you start to see the ionized calcium around the faculae and magnetic activity regions.

So basically:

540nm - Great all around wavelength when seeing is good for photosphere imaging. Baader Solar continuum filter (540nm +/- 10nm).
656nm - Great long wavelength for when seeing is poor and if you want to see more detail inside of a large sunspot. Astronomik 12nm Ha filter (656nm +/- 12nm).
430nm - Excellent for photosphere imaging with very high contrast and higher angular resolution. Andover surpluss G-band filter (430nm +/- 2nm).
393nm - Excellent for photosphere imaging, also with high contrast and even higher angular resolution, but darker inside of sunspots. Baader K-line filter (395nm +/- 8nm).

Alternatives to Gband & Calcium, you can go around 500nm where OIII narrowband filters are for a similar look (501nm, +/- 10nm) on instruments such as SCT or other mirrors that are poorly corrected for near UV wavelengths. They tend to bottom out around 500nm or so. Good newtonian mirrors, F5 and longer, are fine. And most refractors are of course fine for this (no APO needed when you're focusing a single wavelength of light).

Very best,

Many thanks for this comprehensive reply Martin, it is good to read it from a user perspective rather than just through reading dry data sheets.

Cheers

Dennis

MalVeauX wrote in post #18857989
May 7th 2019,

Looking deep into AR2740 in red wavelength. Red allows you to see deeper into the spot and find structures, as there's generally shallow structures and the deeper black core where temperatures are much cooler than the surrounding structure as magnetic fields whirl around it with material flinging all around the lines. Presented in white light for the photosphere, hydrogen alpha & calcium K for the chromosphere from an 8" F21 solar scope. Small scales provided of both AR2740 & AR2741 from an 80mm F21 solar scope.

IMAGE LINK: https://flic.kr/p/2eC6​UWw

Very best,

Martin,

Without going into depth do you mind telling why some of your photos are in this purplish color?

Thank you

Today (8th May 2019) delivered a pleasant surprise with some improved seeing conditions over Brisbane.

Occasionally, the turbulent atmosphere settled down and produced some moments of steadier seeing as the swirling cells of air that damage image quality passed by. This allowed me to stop and start the imaging run during the steadier periods, in the hope of collecting images when the seeing was at its calmest.

Tak Mewlon 210
TeleVue x2 PowerMate
Baader 3.8 Film and Solar Continuum Filter.
ASI 174 MM camera.

Cheers

Dennis

Inspeqtor wrote in post #18858114
Martin,

Without going into depth do you mind telling why some of your photos are in this purplish color?

Thank you

Hi Charles

Martin is using a specialised Filter Module on his telescope (CaK) which passes the wavelength of 393.4 nm. This wavelength is considered to be slightly outside the visible spectrum on the UV side, hence the colour.

Here is a link to a supplier of CaK Filters for solar imaging.

https://luntsolarsyste​ms.com …k/lunt-calcium-k-modules/

Cheers

Dennis

nardes wrote in post #18858239
Hi Charles

Martin is using a specialised Filter Module on his telescope (CaK) which passes the wavelength of 393.4 nm. This wavelength is considered to be slightly outside the visible spectrum on the UV side, hence the colour.

Here is a link to a supplier of CaK Filters for solar imaging.

https://luntsolarsyste​ms.com …k/lunt-calcium-k-modules/

Cheers

Dennis

Thank you Dennis!

nardes wrote in post #18858139
Today (8th May 2019) delivered a pleasant surprise with some improved seeing conditions over Brisbane.
Dennis

Many thanks for this comprehensive reply Martin, it is good to read it from a user perspective rather than just through reading dry data sheets.

Cheers

Dennis

Lovely captures, I hope these spots stick around for the full transit on the face of the disc!

Inspeqtor wrote in post #18858114
Martin,

Without going into depth do you mind telling why some of your photos are in this purplish color?

Thank you

Simple answer: I colored it that way

I use monochrome sensors, not color. So, all my images are black & white in acquisition, no color, single wavelength. I color them in post processing with what I want. I can make it green or something or whatever I please. Our star is not a yellow or orange star, it's white actually. But we're used to seeing it in deeper orange and red tones from Earth, so I like to use that to color it. In specific astronomy circles we present only in b&w as it's the more accurate representation. I like color though, it's just pleasing. As for purple, I like to use that color because when I image at 393nm, it represents ionized calcium in the cooler, lower chromosphere. This is near UV wavelength, which in general to us would seem purple. So I use that color because its more like what you'd expect to see, if you could see this range of color (we cannot, it's near UV).

Here's the original before I colored it: https://flic.kr/p/2fKe​it9

Very best,

MalVeauX wrote in post #18858403

Inspeqtor wrote in post #18858114
Martin,

Without going into depth do you mind telling why some of your photos are in this purplish color?

Thank you

Simple answer: I colored it that way

Very best,

Thank you for not going into any depth!

Love your answer!!

May 11th 2019,

So, the big spot that was in AR2740 is finally decaying to a mere dipole pore and is losing activity fast, however, the big spot in AR2741 persists and has a lovely bright plage around it with a swirling filament attached, making a whirlwind looking structure around the spot.

White light (656nm loose bandwidth) @ 200mm F18
HA (656.28nm +/- 0.5A) @ 200mm F16
HA (656.28nm +/- 0.5A) @ 80mm F21
CaK (393.37nm +/- 1A) @ 40mm F10

IMAGE LINK: https://flic.kr/p/2eEu​jWu

IMAGE LINK: https://flic.kr/p/THYM​8N

IMAGE LINK: https://flic.kr/p/2fSg​8Bi

IMAGE LINK: https://flic.kr/p/THXZ​dw

IMAGE LINK: https://flic.kr/p/S6J3​cP

IMAGE LINK: https://flic.kr/p/2fMD​JAU

May 14th 2019,

Sunspots in AR2741 is still present, with beautiful light bridges and the spot in AR2740 is a mere pore at this stage. There's a huge bright hedge prominence on the limb too. Presented in hydrogen alpha & calcium k lines representing the chromosphere. Scales are with a 120mm F8 achromat and 80mm F5 achromat.

IMAGE LINK: https://flic.kr/p/S8Up​LP

IMAGE LINK: https://flic.kr/p/25hQ​9gK

IMAGE LINK: https://flic.kr/p/25hQ​6Vc

IMAGE LINK: https://flic.kr/p/25hQ​7Vt

IMAGE LINK: https://flic.kr/p/2fUs​xyx

IMAGE LINK: https://flic.kr/p/2fUs​xS8

IMAGE LINK: https://flic.kr/p/25hQ​8oT

IMAGE LINK: https://flic.kr/p/25hQ​7nz

MalVeauX wrote in post #18861444
May 14th 2019,

Sunspots in AR2741 is still present, with beautiful light bridges and the spot in AR2740 is a mere pore at this stage. There's a huge bright hedge prominence on the limb too. Presented in hydrogen alpha & calcium k lines representing the chromosphere. Scales are with a 120mm F8 achromat and 80mm F5 achromat.

IMAGE LINK: https://flic.kr/p/S8Up​LP AR2741_120mmF17_HA_241​frames_Colored_0514201​9 by Martin Wise, on Flickr

IMAGE LINK: https://flic.kr/p/25hQ​9gK AR2741_AR2740_HA_120mm​F17_241frames_BW_05142​019 by Martin Wise, on Flickr

IMAGE LINK: https://flic.kr/p/25hQ​6Vc Proms_HA_120mmF17_101f​rames_Colored_05142019 by Martin Wise, on Flickr

IMAGE LINK: https://flic.kr/p/25hQ​7Vt AR2741_AR2740_Limb_HA_​DS_R6_181frames_Colore​d_05142019 by Martin Wise, on Flickr

https://flic.kr/p/2fUs​xyxAR2741_AR2740_80mmF15_​CaK_241frames_Colored_​05142019 by Martin Wise, on Flickr

Alternatives:

https://flic.kr/p/2fUs​xS8AR2741_120mmF17_HA_241​frames_Inverted_Colore​d_05142019 by Martin Wise, on Flickr

https://flic.kr/p/25hQ​8oTAR2741_AR2740_HA_120mm​F17_241frames_Inverted​_Colored_05142019 by Martin Wise, on Flickr

https://flic.kr/p/25hQ​7nzAR2741_AR2740_Limb_HA_​DS_R6_181frames_Invert​ed_Colored_05142019 by Martin Wise, on Flickr

Very best,

Wow, that third one looks a bit salacious. (I was just in G&N.)

More seriously - amazing shots.

May 15th 2019,

A final look at the sunspot in AR2741 as I will not be able to see it round the limb due to work. Still active, with a lovely light bridge (which signifies its decay) and a large bright prominence still on the limb. Presented in large scale and medium scales in hydrogen alpha, calcium k and white light to show the chromosphere and photosphere.

IMAGE LINK: https://flic.kr/p/2eHf​JBL

IMAGE LINK: https://flic.kr/p/2eHf​JeG

IMAGE LINK: https://flic.kr/p/2eHf​HVA

IMAGE LINK: https://flic.kr/p/2eHf​JNC

IMAGE LINK: https://flic.kr/p/2eHf​K5Q

IMAGE LINK: https://flic.kr/p/TLJa​om

IMAGE LINK: https://flic.kr/p/25ip​yMn

IMAGE LINK: https://flic.kr/p/TLJ7​vs

May 25th 2019,

Low activity, but a little more than the past few days at least. There's a little plage that formed the other day and is still persistent with some tiny filaments around it and spicule bundles here and there. Some fair prominences are near by on the limb that have lasted the night so far. Seeing was poor today, I couldn't do much beyond HA and getting anything other than small scale was a struggle, go figure, days of clear skies and the seeing is really poor.

B&W: