#1  
Old 28-09-2021, 09:45 AM
Merlin66's Avatar
Merlin66 (Ken)
Spectroscopy Wizard

Merlin66 is offline
 
Join Date: Oct 2005
Location: St Leonards, Vic
Posts: 8,512
MiniSHG and Ha 7nm filter

The attached screen shot shows a few things:
1. The Baader 7nm Ha filter actually has peak transmission at 6580A.
2. The movements in the solar surface are clearly seen as "wiggles" in all the absorption lines.


The measured resolution R=33529 and the dispersion 0.0635 A/pixel match up pretty well with the SimSpec for the MiniSHG.
Attached Thumbnails
Click for full-size image (MiniSHG_7nmHa filter.jpg)
165.9 KB26 views
Reply With Quote
  #2  
Old 28-09-2021, 10:27 AM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
 
Join Date: Oct 2007
Location: Sydney
Posts: 21,589
Pretty cool. Very interesting.
Reply With Quote
  #3  
Old 01-10-2021, 09:42 PM
Rob_K
Registered User

Rob_K is offline
 
Join Date: Oct 2006
Location: Bright, Vic, Australia
Posts: 2,135
Fascinating, thanks Ken!

Cheers -
Reply With Quote
  #4  
Old 02-10-2021, 06:29 AM
Merlin66's Avatar
Merlin66 (Ken)
Spectroscopy Wizard

Merlin66 is offline
 
Join Date: Oct 2005
Location: St Leonards, Vic
Posts: 8,512
OK,
I think what has happened is the "light sharpening" has caused some artefacts which exaggerate the wiggles.
In an un-sharpened version the wiggles are obvious in the Ha etc. and not in the tellurics.
Reply With Quote
  #5  
Old 02-10-2021, 06:55 AM
JA
.....

JA is offline
 
Join Date: Oct 2016
Location: Melbourne, Australia
Posts: 2,348
Quote:
Originally Posted by Merlin66 View Post
The attached screen shot shows a few things:
1. The Baader 7nm Ha filter actually has peak transmission at 6580A.
2. The movements in the solar surface are clearly seen as "wiggles" in all the absorption lines.


The measured resolution R=33529 and the dispersion 0.0635 A/pixel match up pretty well with the SimSpec for the MiniSHG.
Hi Ken,

The peak transmission is an interesting result. I wonder if the bandwidth is to spec. In trying to deduce this from the graph, I'd be curious to know the vertical scale and starting point/zero. Thanks for sharing your work - very interesting Ken

Best
JA
Reply With Quote
  #6  
Old 02-10-2021, 07:04 AM
Merlin66's Avatar
Merlin66 (Ken)
Spectroscopy Wizard

Merlin66 is offline
 
Join Date: Oct 2005
Location: St Leonards, Vic
Posts: 8,512
JA,
Looking at the peak @ 6580A and assessing the FWHM (based on the visible curve in the blue wing) the 50% line seems to be at 6545A.
This would give a FWHM of 2 x 35A = 70A which is the Baader spec.
Reply With Quote
  #7  
Old 02-10-2021, 07:31 AM
JA
.....

JA is offline
 
Join Date: Oct 2016
Location: Melbourne, Australia
Posts: 2,348
Quote:
Originally Posted by Merlin66 View Post
JA,
Looking at the peak @ 6580A and assessing the FWHM (based on the visible curve in the blue wing) the 50% line seems to be at 6545A.
This would give a FWHM of 2 x 35A = 70A which is the Baader spec.
Thx Ken. So if the 50% transmission line passes through 6545A and knowing that the max transmission for this filter is probably around ~88-90% (from Baader literature for the 7nm CCD) that makes the Ha transmission not that great, around 65-70% very roughly.... Yes? If so, as an aside, that's quite a revelation, since when you look at the data when comparing filters, the graphs do not have such fine resolution and clearly could lead to the wrong impression of what represents a good filter for a particular application/ budget.

Best
JA

Last edited by JA; 02-10-2021 at 07:44 AM.
Reply With Quote
  #8  
Old 02-10-2021, 09:53 AM
Merlin66's Avatar
Merlin66 (Ken)
Spectroscopy Wizard

Merlin66 is offline
 
Join Date: Oct 2005
Location: St Leonards, Vic
Posts: 8,512
JA,
Yes, that sounds about right.
You could probably tilt the filter to get better transmission.....
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 07:27 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Advertisement
Limpet Controller
Advertisement
NexDome Observatories
Advertisement
Testar
Advertisement
Bintel
Advertisement
Astronomy and Electronics Centre
Advertisement