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2009-04-05 Atmospheric Effects on Focus Collimation Check Flat Frames >
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Focus Profiles |
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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.
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Collimation Measurement - 2009-04-01 (post Re-Collimation) |
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CCD Inspector plot 15s sec exposure, 2x2 binning, C Filter (#360292) 12" LX200R (at f/5.7) + ST-10XME |
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Collimation Check - 2009-04-05 |
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CCD Inspector plot 20s sec exposure, 2x2 binning, C Filter (#361021) 12" LX200R (at f/5.7) + ST-10XME |
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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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Dawn Flats were taken using C filter (1x1, 2x2, 3x3),
BVR filters (3x3) and U filter (1x1, 3x3)
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Flat Analysis Map / CCD Inspector - 2009-04-05
(S361) Corner vignetting : 9%, 9%, 11%, 13% |
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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 |
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Previous Flat Analysis Map / CCD Inspector - 2009-03-26
(S358) Corner vignetting : 8%, 8%, 12%, 14% |
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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 : | 2009-05-07 |
| Site Owner : | David Richards |
| Home Page : | David's Astronomy Web Site |
