David's Astronomy Pages
 Notes - Session 361 (2009-04-05)

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2009-04-05
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Goto Images from 2009-04-05

Atmospheric Effects on Focus

Focus Profiles

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Collimation Checks

Collimation tuning was performed at the end of the last session (S360). Final estimated collimation error was around 3 - 4 arc secs, compared to a immediately prior collimation error of 14 arc secs (and compared against original first light collimation error of around 35-42 arc secs). It was unclear why the collimation error immediately prior to re-collimation attempt (14 arc secs) was rather less than the measurements made during session S358 (31-37 arc secs)  (Mirror slop ?, seeing).

To investigate the collimation behavior of the scope, a collimation check was made on a star field lying at around 52 deg altitude.  Collimation error (20-25 arc sec) appears to have increased from that shown in the last session, but is still lower then measurements made during S358.   It would seem that whilst sub-5 arc sec collimation was not reliable, a 10 arc secs improvement was nevertheless made. 

Collimation Measurement  - 2009-04-01 (post Re-Collimation)

Image
CCD Inspector plot 
15s sec exposure, 2x2 binning, C Filter (#360292)
12" LX200R  (at f/5.7) + ST-10XME

  

Collimation Check  - 2009-04-05
(collimation has appeared to have degraded)

Image
CCD Inspector plot 
20s sec exposure, 2x2 binning, C Filter (#361021)
12" LX200R  (at f/5.7) + ST-10XME

  

Table of Collimation / Curvature Measurements  - 12" LX200R  (at f/5.7) + ST-10XME

Session  Images Stars
 Aspect
Ratio
 Curvature
    Collimation 
(arc secs)		    Average FWHM
(arc secs) 		   Tilt X    Tilt Y    Total Tilt
S356 (First Light Session)  30 x 30s 148 +/- 13 38 % +/- 20% 16 % +/- 1% 41.6" +/- 6.3" 5.4" +/- 0.7"   -0.9" +/- 0.1"   -0.3" +/- 0.1"   16% @ -157 deg
S356 (First Light Session)  6 x 60s 410 +/- 22 38 % +/- 10% 27 % +/- 1% 35.0" +/- 6.5" 5.3" +/- 0.3"   -1.1" +/- 0.2"   +0.5" +/- 0.1"   20% @ -149 deg
S357 collimination attempt
S358  7 x 90s 575 +/- 40 19% +/- 8% 24 % +/- 2% 36.3" +/- 6.3" 5.5" +/- 0.4"   +0.9" +/- 0.2"   +0.1" +/- 0.1"   15% @ - 5 deg
S358  6 x 45s 633 +/- 73 14% +/- 3% 21 % +/- 2% 31.7" +/- 7.6" 4.9" +/- 0.4"   +0.7" +/- 0.2"   +0.3" +/- 0.1"   10% @ - 22 deg
S358  3 x 60s 695 +/- 80 16% +/- 6% 24 % +/- 1% 36.1 +/- 4.0" 5.9" +/- 0.6"   +0.9" +/- 0.1"   +0.1" +/- 0.0"   14% @ - 9 deg
S360  2 x 20s 199 +/- 1 16% +/- 4% 22 % +/- 3% 13.9 +/- 1.3" 4.0" +/- 0.2"   +0.6" +/- 0.1"   +0.0" +/- 1.0"   12% @ - 9 deg
S360  3 x 20s 184 +/- 27 27% +/- 5% 24 % +/- 6% 14.7 +/- 1.5" 4.2" +/- 0.3"   +0.5" +/- 0.1"   -0.1" +/- 0.1"   12% @ 19 deg
S360 - Collimation attempt
S360 - Post Collimation 4 x 20s 223 +/- 13 17% +/- 1% 17 % +/- 3% 3.7 +/- 1.0" 4.0" +/- 0.1"   +0.2" +/- 0.1"   -0.1" +/- 0.1"   4% @ 20 deg
S361  2 x 20s 412 +/- 65 14% +/- 1% 22 % +/- 1% 25.1 +/- 5.7" 4.5" +/- 0.1"   +0.8" +/- 0.1"   -0.4" +/- 0.1"   15% @ -33 deg

 

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Flat Frames  

Dawn Flats were taken using C filter (1x1, 2x2, 3x3),  BVR filters (3x3) and U filter (1x1, 3x3)

Flat Analysis Map / CCD Inspector - 2009-04-05 (S361) 
Corner vignetting : 9%, 9%, 11%, 13%
Image
Master Flat Frame / Dawn Flat
15 x 1s exposure (average combine), 3x3 binning, C Filter, 
2009-04-05, 12" LX200R  (at f/5.7) + ST-10XME
  
Previous Flat Analysis Map / CCD Inspector - 2009-03-26 (S358) 
Corner vignetting : 8%, 8%, 12%, 14%
 Image
Master Flat Frame
15 x 1s exposure (average median combine), 1x1 binning, C Filter
2009-03-26, 12" LX200R  (at f/5.7) + ST-10XME

 

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This Web Page: Notes - Session 361 (2009-04-05)
Last Updated : 2015-05-16
Site Owner : David Richards
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