MBCAA Observatory
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Transformation coefficients (with weights): V,Ic measurementsObserved: 7 Jan 2005, 5, 6, 12, 15 Sept 2007Michel Bonnardeau
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Run | Session | Field | Nb of stars |
V-Ic range |
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value | error | value | error | value | error | |||||
0 | 20050107 | L95 | 14 | 2.094 | 0.971 | 0.042 | -0.011 | 0.018 | 0.020 | 0.021 |
1 | 20070905 | L110 North | 8 | 1.973 | 0.970 | 0.001 | 0.004 | 0.003 | 0.015 | 0.003 |
2 | 20070905 | L110 South | 9 | 2.147 | 0.983 | 0.009 | 0.004 | 0.008 | 0.006 | 0.001 |
3 | 20070906 | L110 North | 8 | 1.973 | 0.961 | 0.001 | -0.001 | 0.003 | 0.018 | 0.002 |
4 | 20070906 | L110 South | 9 | 2.154 | 0.985 | 0.003 | -0.002 | 0.005 | 0.004 | 0.002 |
5 | 20070912 | L110 North | 8 | 1.973 | 0.977 | 0.001 | 0.014 | 0.003 | 0.017 | 0.003 |
6 | 20070912 | L113 | 7 | 0.591 | 0.862 | 0.021 | -0.080 | 0.045 | 0.110 | 0.002 |
7 | 20070912 | L95 | 8 | 1.168 | 1.021 | 0.061 | 0.003 | 0.013 | -0.021 | 0.041 |
8 | 20070915 | L110 North | 6 | 0.830 | 0.931 | 0.035 | 0.042 | 0.022 | 0.131 | 0.017 |
The transformed V,I magnitudes of the star being studied are computed
the following way:
V = v + TIv*Tvi*((v-i)-(Vo-Io))
I = V - [(Vo-Io) + Tvi*((v-i)-(Vo-Io))]
or
I=i + Ti*Tvi*((v-i)-(Vo-Io))
V = I+ (Vo-Io) + Tvi*((v-i)-(Vo-Io))
where Vo,Io are the magnitudes of the comparison star and v,i the observed
magnitudes of the star being studied. The only coefficients that are useful
for the transformations are then Tvi, TIv*Tvi, Ti*Tvi:
The coefficients are fairly stable; the most discrepant measurements are
for runs 6 and 8 that have the smallest V-I range. The adopted values
and uncertainties are the weighted average values and the weighted standard
deviations:
(N the number of observations, deltaTi the uncertainty/error
on observation i)
Tvi = 0.970 +/- 0.008
TIv*Tvi = 0.003 +/- 0.007
Ti*Tvi = 0.019 +/- 0.018
Telescope and camera configuration.
Computer and software configuration.
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