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

Notes (S429)

Notes Main

Home Page

Notes (S449)

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

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)

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

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

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 .

Back to Top

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

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

Back to Top

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 .

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)

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

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

Back to Top