David's Astronomy Pages
Notes - Session 435 (2010-11-10)

2010-11-10
Bullet Spectral Image Focusing
Bullet Spectra Filter Test for Zero Order Shift
   
Bullet Images from 2010-11-10 >>
   
2010-11-15
Bullet Spectral Image Focusing Update

Spectral Image Focusing

Spectral Focus Profile, measured over a 20 pixel wide window 
covering part of the first order spectrum
(Star Analyser 100)
Image
Realtime observatory graph
Filter : Star Analyser 100 filter / Star : a star in Vulpecula
2010-11-10 18:04 to 18:08h (profile S435-3)
12" LX200R  (at f/9.7) + ST-10XME + Optec TCF-S
 
Comparison between first order and zero order focus 
A difference of 215 steps is noted between the best focus positions
(note : first and zero order measurements made on same image)
Image
Excel Graph
Filter : Star Analyser 100 filter / Star : a star in Vulpecula
2010-11-10 18:04 to 18:08h (profile S435-3)
12" LX200R  (at f/9.7) + ST-10XME + Optec TCF-S
 
Representative Image at best first order focus
Image
Annotated CCD Spectral Image
Star : HIP 98375 (F0)  in Vulpecula
5s exposure (single frame), 1x1 binning, S Filter 
2010-11-10 18:06h (Snap.1805.49.focus_2883)
12" LX200R  (at f/9.7) + ST-10XME
 
Representative Image at best zero order focus
Image
Annotated CCD Spectral Image
5s exposure (single frame), 1x1 binning, S Filter 
2010-11-10 18:07h (Snap.1806.55.focus_3093)
12" LX200R  (at f/9.7) + ST-10XME
 
Update - 2010-11-15
Instead of focusing over a vertical column centred around the middle width position (as shown above)
a new facility has been added on 2010-11-15 whereby a rectangular area is draw 
over the first order spectrum in order to set up a precise focus window .

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Spectra Filter Test for Zero Order Shift

Spectra Filter Test for Zero Order Shift

Back to back images of HIP 98375 taken through C Filter and Star Analyser 100
were taken and a blink comparison made (animation captured below).

The test confirms that the zero order images taken through Star Analyser 100 
is for practical purposes exactly coincident with star position taken 
through normal filter, showing that there is no image shifting.
This is important confirmation as it makes it easier to design automated autoguiding routines
Image
Animated CCD Images (cropped / no alignment of images)
a) 3s exposure (single frame), 3x3 binning, C Filter 
b) 3s exposure (single frame), 3x3 binning, S Filter 
2010-11-10 17:46h (429179)
12" LX200R  (at f/9.7) + ST-10XME

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Spectral Image Focusing Update

Focusing Update - 2010-11-15
Instead of focusing over a vertical column centred around the middle width position (as shown above)
a new facility has been added on 2010-11-15 whereby user can draw a rectangular area 
over the required section of first order spectrum in order to set up a more precise focus window .
Image
Screen Capture of a realtime observatory image
1s exposure, 1x1 binning, S Filter,  2010-11-15
 
Spectral Focus Profile, measured over rectangular focus window 
covering first order spectrum
(Star Analyser 100)
Image
Realtime observatory graph
Filter : Star Analyser 100 filter / Star : HIP 117718 in Pegasus
2010-11-15 20:06 to 20:09 (profile S437-3)
12" LX200R  (at f/9.7) + ST-10XME + Optec TCF-S
 
Representative Image at best first order focus
Image
CCD Spectral Image
Star : HIP 117718 (M2iii)  in Pegasus
1s exposure (single frame), 1x1 binning, S Filter 
2010-11-15 20:08h (Snap.2008.05.focus_2594)
12" LX200R  (at f/9.7) + ST-10XME

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