2009-04-01
	Reduced Star Drift
	Tracking Rate Adjustment Trials
	Seeing / Atmospheric Refraction Effect
	Collimation and Image Curvatures Measurements
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Results of recent PEC Training and Tracking Rate Adjustment,  2009-04-01 Non-aligned Stacked frames from a 16 minute period (smeared star frames not used) /  IC 531 starfield No Guiding, PEC On, Tracking Rate Adjustment +1 (+0.1%) Star drift (RA) : 0.9 arc secs/min westwards: Star drift (Dec): 0.6 arc secs/min northwards Periodic error :  5 arc secs (estimate)  + larger 10 arc sec error

Annotated CCD Image  32 x 15s sec exposure (average combined / no alignment on stars)  3x3 binning, C Filter, Cropped 2009-04-01 20:00 - 21:16h UT (#360001-46) 12" LX200R  (at f/5.7) + ST-10XME

Earlier Star drift and periodic error effects  - 2009-03-09 Stacked Images from a 16 minute period,  C/2007 N3 (Lulin) starfield No Alignment, No PEC, No Adjustment to Tracking Rate. Star drift (RA) : 2 arc secs/min westwards: Star drift (Dec) : 0.25 arc sec/min northwards Periodic Error : 30 arc secs Note: Comet C/2007 N3 (Lulin) records a higher drift rate due to its motion relative to background stars.

Annotated CCD Image  30 x 30s sec exposure (average combined / no alignment on stars or comet)  3x3 binning, C Filter, Cropped 2009-03-09 21:08 - 21:24h UT (#356006-35) 12" LX200R  (at f/5.8) + ST-10XME

Star Drift (RA) Measurements / IC 531 starfield, 2009-04-01

Positional measurements on from a 16 minute period (smeared star frames not used) No Guiding, PEC On, Tracking Rate Adjustment +1 (+0.1%) Whilst the first and last frame (16 minutes later) show no RA drift, it is evident that the run comprises two sections 1) initial eastwards drift at 2.5 arc sec/minute   (5 minutes) 2)westwards drift at 0.9 arc secs/minute  (11 miutes) (The reason of the initial eastwards drift lasting around 5 minutes is currently unexplained) Assuming the drift rate of 0.9 arc secs/minute for the longer second section, the residual periodic error is around 5 arc secs

Star Drift (RA) Measurements / NGC 2877 starfield, 2009-04-01

Positional measurements on from a 16 minute period (NGC 2877) No Guiding, PEC On, Tracking Rate Adjustment +2 (+0.2%) The residual periodic error is around 5.5 arc secs.

Session		Tracking Rate Adjustment		Star Drift (in RA)		Actual Tracking Rate		Notes
S356/357		'Sidereal'		Westwards by 1.9 arc secs/minute		Slow by 0.21%		South Sky Point (w/o Pec)
S358a		'Sidereal'		Westwards by 3.2 arc secs/minute		Slow by 0.34%		South Sky Point (with Pec)
				Westwards by 4.1 arc secs/minute		Slow by 0.34%		West Sky Point (with Pec)
S358b		+3		Eastwards by 2.5 arc secs/minute		Fast by 0.28%		South Sky Point (with Pec)
S359		+1		Westwards by 2.2 arc secs/minute		Slow by 0.24%		South Sky Point (w/o Pec)
S360		+1		Westwards by 0.9 arc secs/minute ?		Slow by 0.09% ?		South Sky Point (with Pec)
		+2		Eastwards by 1.0 arc secs/minute		Fast by 0.11%		South Sky Point (with Pec)

Results of recent PEC Training and Tracking Rate Adjustment,  2009-04-01 Non-aligned stacked frames from a 16 minute period (all frames) No Guiding, PEC On, Tracking Rate Adjustment +1 (+0.1%) RA Drift  Note : Elongation of stars is at least in part due to a seeing/atmospheric refraction effect
Annotated CCD Image  46 x 15s sec exposure (average combined / no alignment on stars)  3x3 binning, C Filter, Cropped 2009-04-01 20:00 - 21:16h UT (#360001-46) 12" LX200R  (at f/5.7) + ST-10XME
Frame with Smeared/Elongated Stars
Annotated CCD Image (65% size reduction, with 150% size insert) 15s sec exposure (single frame), 3x3 binning, C Filter 2009-04-01 (#360001), 12" LX200R  (at f/5.7) + ST-10XME
Normal Frame - circular stars
Annotated CCD Image (65% size reduction, with 150% size insert) 15s sec exposure (single frame),  3x3 binning, C Filter 2009-04-01 (#360029), 12" LX200R  (at f/5.7) + ST-10XME
Frames showing orientation of smeared stars relative to horizon grid lines
CCD Images (Image Linked within TheSky with Horizon Grid lines - brown)) 15s sec exposure (single frames),  3x3 binning, C Filter 2009-04-01 (#360001, 360010, 360018, 236004)), 12" LX200R  (at f/5.7) + ST-10XME

Collimation Measurements (pre Re-Collimation)

CCD Inspector plot  20s sec exposure,  2x2 binning, C Filter (#360245) 12" LX200R  (at f/5.7) + ST-10XME

Collimation Measurement  (post Re-Collimation)

CCD Inspector plot  20s sec exposure, 2x2 binning, C Filter (#360292) 12" LX200R  (at f/5.7) + ST-10XME

Image Prior to Re-Collimation

CCD Image  (50% size reduction) 20s sec exposure (single frame),  3x3 binning, C Filter 2009-04-1 21:08 - 21:24h UT (#360245) 12" LX200R  (at f/5.7) + ST-10XME

Image After Re-Collimation Optical centre moved total of 4.9 arc mins during re-collimation as measured by star positions before & after.

CCD Image  (50% size reduction) 20s sec exposure (single frame),  3x3 binning, C Filter 2009-04-1 21:08 - 21:24h UT (#360292) 12" LX200R  (at f/5.7) + ST-10XME

Graphs showing progressive improvement in Collimation Quality during re-collimation  a reasonable collimation position was obtained part way through the sequence  but was lost again as further improvement was attempted. Collimation attempt was stopped when approximately equivalent quality was obtained.

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 collimation 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