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On Oct 4, 2004, at 1:05 AM, Alexandre Eremenko wrote:
> After many repeated measurements I found the star-to-itself
> method more precise than the Sun method. This is the case
> with my sextant, my scopes and my specific observation
> conditions, I do not generalize this to all situations.
> (Unfortunately I have no possibility to use real
> horizon at this time).
>
> I can post the numerical data if this is interesting.
>
> However I don't know of any other method (other than star-to-star
> distances) of measuring what you call "centering error"
> without special equipment.
> This should answer your sentences:
> You say that the better method was:
>
>> At one time, an instrument
>> could be sent off for testing by a system of
>> collimators,
>
> But I don't have a collimator. And many other people don't.
> Bougainville :-) who used the stars for a similar test,
> as described in the recent messages:

Alex,

I would like to see some of your star data for index error.  I post
below some sun data, with a few moon determinations.

Regarding machines for determining centering error (the centering of
the pivot of the index arm), I don't believe those are called
collimators.  I believe a collimator is for determining centering of
the telescope.  The machines and operators, together encompassing a
service, for determining centering error are not available in the U.S.,
to the best of my knowledge, except possibly at the Warren-Knight
Instrument Co., .

Fred

date&zone time  object,sextant  on'     off' IndexError"        SD'

09/05/2004 15:15        sun, C+P        32.4    31.1    39      15.88
09/05/2004 15:15                32.4    31.1    39      15.88
09/05/2004 15:15                32.4    31.2    36      15.90
09/05/2004 15:55        sun, C+P        32.3    31.5    24      15.95
09/05/2004 15:55                32.2    31.3    27      15.88
09/05/2004 15:55                32.2    31.5    21      15.93
09/06/2004 10:30        sun, C+P        31.7    31.75   -1.5    15.86
09/06/2004 10:30                31.8    31.9    -3      15.93
09/06/2004 10:30                31.8    31.9    -3      15.93
09/10/2004 19:00        sun, C+P        31.6    32.1    -15     15.93
09/10/2004 19:00                32      32      0       16.00
09/10/2004 19:00                31.8    32      -6      15.95
09/11/2004 16:40        sun, C+P        32.1    31.8    9       15.98
09/11/2004 16:40                31.9    31.8    3       15.93
09/11/2004 16:40                32      31.9    3       15.97
09/19/2004 17:45        sun, C+P        31.8    32      -6      15.95
09/19/2004 17:45                31.7    32.1    -12     15.95
09/19/2004 17:45                31.7    32      -9      15.93
09/20/2004 18:15        sun, C+P,       31.2    32.6    -42     15.95
09/20/2004 18:15                31.4    32.4    -30     15.95
09/20/2004 18:15                31.3    32.3    -30     15.90
09/21/2004 17:00        sun, C+P        31.5    32.4    -27     15.97
09/21/2004 17:00                31.7    32.4    -21     16.02
09/21/2004 17:00                31.8    32.2    -12     16.00
09/22/2004 14:00        sun, C+P        32.1    31.9    6       16.00
09/22/2004 14:00                32      31.9    3       15.97
09/22/2004 14:00                32.3    31.9    12      16.05
09/23/2004 17:30        sun, C+P,       31.8    32.6    -24     16.10
09/23/2004 17:30                32      32.4    -12     16.10
09/23/2004 17:30                32.1    32.4    -9      16.12
09/24/2004 22:30        moon, C+P       32.5    32.7    -6      16.30
09/24/2004 22:30                32.3    32.6    -9      16.23
09/24/2004 22:30                32.4    32.7    -9      16.27
09/26/2004 09:45        sun, C+P,       31.7    32.5    -24     16.05
09/26/2004 09:45                31.8    32.4    -18     16.05
09/26/2004 09:45                31.9    32.4    -15     16.07
09/29/2004 05:50        sun, C+P,       31.5    32.65   -34.5   16.04
09/29/2004 05:50                31.5    32.8    -39     16.07
09/29/2004 05:50                31.4    32.7    -39     16.02
09/29/2004 22:00        moon, C+P       30.3    31.3    -30     15.40
09/29/2004 22:00                30.2    31.6    -42     15.45
09/29/2004 22:00                30.3    31.4    -33     15.43
09/30/2004 17:20        sun, C+P        31.7    32.45   -22.5   16.04
09/30/2004 17:20                31.5    32.5    -30     16.00
09/30/2004 17:20                31.5    32.4    -27     15.97
10/01/2004 16:40        sun, C+P        31.5    32.6    -33     16.02
10/01/2004 16:40                31.6    32.4    -24     16.00
10/01/2004 16:40                31.6    32.4    -24     16.00
10/02/2004 10:00        sun, C+P        31.7    32.3    -18     16.00
10/02/2004 10:00                31.7    32.4    -21     16.02
10/03/2004 13:45        sun, C+P,       32      32      0       16.00
10/03/2004 13:45                32.1    31.7    12      15.95
10/03/2004 13:45                32      32      0       16.00

   

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