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 Notes - Session 210 (2007-09-03)

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Bullet TPoint Mapping Run (2007-09-03)
 
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Goto Images from 2007-09-03

TPoint Mapping Run (2007-09-03)

A TPoint mapping run was conducted comprising 80 mapped points, using an automated script  (Time to complete 60 minutes).

[ Lesson Learnt : Remember to synchronise computer time before starting a TPoint run. I forgot to do this, and a subsequent check showed that computer time was out by ~ 5 secs. This will have produced an error equivalent to 1.25 arc min (75 arc sec).  

Raw Points - RMS  5.1 arc min (305 arc secs )
Image
# Term Value Sigma S/N
 
 

 
 

TPoint fit (2 terms) - RMS 5.0 arc min (299 arc secs)
Image
# Term Value Sigma S/N
1 IH -69.0 39.4 1.8
2 ID 15.2 33.4 0.5

2 terms (Index Error HA, Index Error Dec)
 

TPoint fit (6 terms) - RMS 4.4 arc mins (266 arc secs)
ME Sigma 50 / MA Sigma 40 
Image
# Term Value Sigma S/N
1 IH -456.6 501.1  0.9
2 ID 139.0 41.3 3.4
3 NP -198.1 278.6 0.7
4 CH 407.2 535.5 0.8
5 ME -212.5 50.1 4.2
6 MA -38.4 40.4 1.0

6 basic (equatorial) terms
 

TPoint fit (8 terms) - RMS 3.2 arc mins (191 arc secs)
ME Sigma 86 / MA Sigma 29 
Image
# Term Value Sigma S/N
1 IH -416.2 361.4 1.2
2 ID -347.6 63.9 5.4
3 NP -250.2 200.8 1.2
4 CH 415.4 386.1 1.1
5 ME 276.5 86.0 3.2
6 MA -63.0 29.3 2.1
7 TF -701.3 84.1 8.3
8 FO -368.4 96.6 3.8

6 basic (equatorial) terms 
+ Fork Flexure(TO) + Tube Flexure (TF)
  

Improved TPoint fit (9 terms) -  RMS 86 arc secs 
ME Sigma 51 / MA Sigma 13
Image
# Term Value Sigma S/N
1 IH -425.2 163.0 2.6
2 ID -452.3 84.5 5.4
3 NP -198.4 90.6 2.2
4 CH 363.9 174.1 2.1
5 ME -180.1 51.3 3.5
6 MA -81.9 13.3 6.1
7 TF -832.8 144.5 5.8
8 HCES 514.6 70.7 7.3
9 HDCD2 177.3 71.4 2.5

9 terms : 
6 basic (equatorial) terms 
+ Tube Flexure(TF) + two Harmonic terms

Corresponding Polar Alignment Information 
Northern Hemisphere

************* AZIMUTH ************
MA: -82 seconds (-1.4 minutes).
Rotate axis East (clockwise).
For latitude 57.32°, the azimuth adjustment is 2.5 minutes.
Sigma=13.326

************* ALTITUDE ************
ME: -181 seconds (-3.0 minutes).
The polar axis should be lowered -181 seconds (-3.0 minutes).
Sigma=51.274
  (note relatively higher sigma value of ME term)

TPoint fit (8 terms) -  RMS 103 arc secs 
ME Sigma 26 / MA Sigma 16
# Term Value Sigma S/N
1 IH -434.3 194.4 2.2
2 ID 26.5 18.5 1.4
3 NP -196.8 108.0 1.8
4 CH 368.8 207.6 1.8
5 ME -446.7 26.4 16.9
6 MA -87.2 15.9 5.5
7 HCES 128.2 26.8 4.8
8 HDCD2 568.1 26.7 21.3

8 terms : 
6 basic (equatorial) terms 
+ two Harmonic terms

 

Polar Alignment Information from 8 terms (excl Tube Flexure)
Northern Hemisphere

************* AZIMUTH ************
MA: -87 seconds (-1.5 minutes).
Rotate axis East (clockwise).
For latitude 57.32°, the azimuth adjustment is 2.7 minutes.
Sigma=15.855

************* ALTITUDE ************
ME: -448 seconds (-7.5 minutes).
The polar axis should be lowered -448 seconds (-7.5 minutes).
Sigma=26.422

  

Improved TPoint fit ( 9 terms) -  6 basic terms + New attempt to find a good fit (involving 10 terms), but with low sigma values for ME & MA
Image
# Term Value Sigma S/N
1 IH -428.0 167.8 2.6
2 ID 260.9 16.2 16.1
3 NP -192.2 93.2 2.1
4 CH 361.4 179.2 2.0
5 ME -460.5 23.0 20.0
6 MA -84.0 13.7 6.1
7 HDCD3 445.7 21.1 21.1
8 HHSH1 136.9 23.2 5.9
9 HDSD6 -74.3 19.0 3.9
10 HDSH6 -23.3 15.4 1.5

9 terms : 
6 basic (equatorial) terms 
+ Tube Flexure(TF) + two Harmonic terms

 

Corresponding Polar Alignment Information 
MA: -84 seconds (-1.4 minutes).
Rotate axis East (clockwise).
For latitude 57.32°, the azimuth adjustment is 2.6 minutes.
Sigma=13.691

************* ALTITUDE ************
ME: -462 seconds (-7.7 minutes).
The polar axis should be lowered -462 seconds (-7.7 minutes).
Sigma=22.992

  

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