Doppler Image Jan 30

I LOVE finding out about different ways to appreciate the Sun and light in general. Use this forum to post your info or questions about various outside the mainstream ways to appreciate our life giving star!
Post Reply
User avatar
PDB
Almost There...
Almost There...
Posts: 702
Joined: Mon Aug 15, 2016 4:23 pm
Location: Belgium
Has thanked: 2 times
Been thanked: 149 times

Doppler Image Jan 30

Post by PDB »

Hi,

spent some time on making a doppler image of an H-Alfa capture this morning with the Sol'Ex SHG. (before clouds spoiled the session)
Images generated with +3 /-3 pixel shift (0.59A) and then combined in a color image.
Maybe still need to work a bit on the technique, but not too bad ...
fizeau.jpg
fizeau.jpg (749.97 KiB) Viewed 899 times
Regards,

Paul
Last edited by PDB on Sun Jan 30, 2022 3:22 pm, edited 1 time in total.


None of my posts or images may be shared on Facebook, Twitter or any other social media other than SolarChat without permission.
User avatar
Montana
Librarian
Librarian
Posts: 34527
Joined: Mon Oct 17, 2011 5:25 pm
Location: Cheshire, UK
Has thanked: 17523 times
Been thanked: 8763 times

Re: Doppler Ilage Jan 30

Post by Montana »

Wow!! I like it :bow :bow :bow I take it that red is red shift and blue is blue shift?

Alexandra


User avatar
PDB
Almost There...
Almost There...
Posts: 702
Joined: Mon Aug 15, 2016 4:23 pm
Location: Belgium
Has thanked: 2 times
Been thanked: 149 times

Re: Doppler Image Jan 30

Post by PDB »

Hi Alexandra;

yes it is supposed to be like that, unless I accidentally switched colors. I took +3 px for red and -3px for blue.
The green channel is created by averiging the blue and red one.

Rgrds,

Paul


None of my posts or images may be shared on Facebook, Twitter or any other social media other than SolarChat without permission.
User avatar
marktownley
Librarian
Librarian
Posts: 42131
Joined: Tue Oct 18, 2011 5:27 pm
Location: Brierley Hills, UK
Has thanked: 20240 times
Been thanked: 10113 times
Contact:

Re: Doppler Image Jan 30

Post by marktownley »

Looks great Paul!


Image
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
User avatar
rsfoto
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 6124
Joined: Mon Jun 18, 2012 8:30 pm
Location: San Luis Potosi, México
Has thanked: 9243 times
Been thanked: 5503 times

Re: Doppler Image Jan 30

Post by rsfoto »

Hi Paul,

Interesting but I have to ask. What does this show ? I have seen the Dopplergramm posted in the SDO website but it looks completely different.

Thanks Rainer


regards Rainer

Observatorio Real de 14
San Luis Potosi Mexico

North 22° West 101°
User avatar
p_zetner
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 1644
Joined: Sun Mar 18, 2012 4:59 pm
Location: Winnipeg, Manitoba, Canada
Has thanked: 166 times
Been thanked: 719 times

Re: Doppler Image Jan 30

Post by p_zetner »

Hi Paul.

Nice dopplergram but I agree with Rainer that your version is different from the standard type of dopplergram from SDO. There are probably two reasons for this. One reason for the difference lies in your use of the green channel which contains the velocity averaged information whereas a true dopplergram simply uses the difference (red minus blue or vice versa). You are actually presenting a true dopplergram superimposed on a conventional image - which can be useful for correlating velocity fields with actual feature locations. The other reason is that your dopplergram is created in H alpha (chromospheric) while the SDO image (on the NASA site) is likely using a photospheric line (although I can’t find the information on the site).

Cheers.
Peter


User avatar
PDB
Almost There...
Almost There...
Posts: 702
Joined: Mon Aug 15, 2016 4:23 pm
Location: Belgium
Has thanked: 2 times
Been thanked: 149 times

Re: Doppler Image Jan 30

Post by PDB »

Thank you for the comments Peter. I did several tries (also with 2 channels) but could not get good results (probably combining the wrong way) So I switched to what is descrived on the Sol'Ex page from Christian Buil) using an average of the 2 channels as green channel.

Regards,

Paul


None of my posts or images may be shared on Facebook, Twitter or any other social media other than SolarChat without permission.
User avatar
p_zetner
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 1644
Joined: Sun Mar 18, 2012 4:59 pm
Location: Winnipeg, Manitoba, Canada
Has thanked: 166 times
Been thanked: 719 times

Re: Doppler Image Jan 30

Post by p_zetner »

Hi Paul.

You’ve probably done this already, but why not try different pixel shifts and see if you can intensify the structure in the dopplergram? As you progress outwards from line centre you are “tuning” to faster velocities and these higher velocities might prevail near the active region.

Cheers.
Peter


User avatar
p_zetner
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 1644
Joined: Sun Mar 18, 2012 4:59 pm
Location: Winnipeg, Manitoba, Canada
Has thanked: 166 times
Been thanked: 719 times

Re: Doppler Image Jan 30

Post by p_zetner »

I’d recommend this paper, described by many as groundbreaking. It’s old and deals with film capture but it is relatively straightforward to “translate” into digital spectroheliography.

Velocity Fields in the Solar Atmosphere. I.
Preliminary Report.
Leighton, Robert B. ; Noyes, Robert W. ; Simon, George W.
1962ApJ...135..474L

https://ui.adsabs.harvard.edu/abs/1962A ... L/abstract

Regards.
Peter


Post Reply