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VIMOS Quality Control:
zeropoints

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zeropoints U
zeropoints B
zeropoints V
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zeropoints I
zeropoints error U sigU sigU
zeropoints error B sigB sigB
zeropoints error V sigV sigV
zeropoints error R sigR sigR
zeropoints error I sigI sigI
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Photometric zeropoints are calculated from exposures of selected Stetson photometric standard star fields that contain also some Landolt stars (Landolt 1992, AJ 104, 340). Stetson fields are often very rich of stars and permit an accurate estimate of zeropoints. However the Stetson catalog is not complete in all bands and in particular U photometry is missing. For U we compute zeropoints using the Landolt stars present in the fields, if any.

WARNING: Zeropoints have been computed using constant extinction coefficients and zero color terms, with the main purpose of instrument and site performance monitoring. Though they are reasonably precise, they are not suitable for accurate photometric calibration.

top Zeropoints

Standard star fields are de-biased and flat-fielded using the most recent bias frames and normalized twilight sky flats. The SExtractor (Source Extractor) software (see Bertin & Arnouts 1996, A&A 117, 393) is run on the reduced images to detect standard stars and to extract their instrumental magnitude ("MAG_BEST" Sextractor parameter). The "MAG_BEST" estimate is in agreement with the values obtained with fixed aperture of 10" diameter.

The instrumental magnitude Minstr = -2.5Log(Flux[ADU/sec]), is then corrected for:

  • Airmass
  • Colour term: this is based on the Stetson/Landolt standard colours, not the instrumental colours
  • Flux is transformed into [e/sec].
Thus we have:

Minstr_corrected = -2.5*Log(Flux[ADU/sec] -2.5*Log(CONAD) + col_term*Colour - cext*Airmass

CONAD is the conversion factor ADU to electrons written in the FITS keyword "HIERARCH ESO DET OUT CONAD". The typical value for the CONAD, in the low gain mode used for Imaging is 1.8 e/ADU. The difference between the corrected instrumental magnitude and the magnitude of the Stetson/Landolt standard gives a measure of the zeropoint (at zero airmass and zero colour). For each night we take the median of all the calculated star zeropoints

Zp = Mcatalog - Minstr_corrected.

To obtain the zero point in ADU/sec, 2.5*Log(CONAD) simply needs to be subtracted from the values trended here.

Pipeline-reduced science images in U, B, V, R, and I filters are photometrically calibrated: they contain in header the keyword : "HIERARCH ESO PRO MAG ZERO" that is the most recent estimate of the zeropoint (Zp) for the filter and quadrant in ADU/sec. To convert science images instrumental magnitudes into standard magnitude the photometric equation is:

magnitude = Minstr_corrected + Zp = -2.5*Log(Flux[ADU/sec] + col_term*Colour - cext*Airmass + Zp .

If Zp is in (ADU/sec) like in the reduced images header, Minstr_corrected should not be corrected for CONAD.

WARNING: Zeropoints have been computed using constant extinction coefficients and zero color terms, with the main purpose of instrument and site performance monitoring. Though they are reasonably precise, they are not suitable for accurate photometric calibrations.

QC1 parameters

parameter QC1 database: table, name procedure
zeropoint vimos_zp_night, zeropoint average of zeropoints from all individual standard star fields observed during the night for the specific filter

Trending

Zeropoints are used to monitor the total throughput of the telescope and the instrument. For trending, averages of all fields observed during each night are used. Zeropoints from individual frames can be obtained via the general QC1 database interface.

History

July 2010: new detectors
2011-03-01: video board of FIERA A exchanged; gain changed for Q2 and Q3
2011-04-18: gain values for all quadrants adjusted


top Colour terms and extinction coefficients

For daily zeropoint computations, average extinction coefficients extimated by FORS are used and the colour terms are set to zero.

Average colour terms and extinction coefficients have been calculated for several observing periods by solving the usual photometric equation:

Mcatalog = 2.5*Log(Flux[e/sec]) - col_term*Colour + cext*Airmass +Zp .

In general, a two step approach has been chosen. Since there are only a few nights available with standard star observations at high airmass, these nights have been selected first and the above equation has been solved simultaneously with a bilinear fit for the variables zeropoint, colour term, and extinction coefficient (basically following the aproach of Harris et al. 1981, PASP 93, 507). In a second step, the extinction coefficient from the first step has been taken and the above equation has been solved for zeropoint and colour term only (but for a larger number of nights). Only photometric nights have been selected (see the definition of photometric nights from FORS) and only observations with airmass between 1.0 and 1.1 or between 1.1 and 1.2 have been taken (depending on the availability of data for a given period). Due to the lower number of stars in U band, a higher airmass range of 1.0 to 1.2 has usually been chosen here.

The following tables report the computed zeropoints, colour terms, and extinction coefficients for different observing periods. Quoted errors are one standard deviation and do not include systematic uncertainties. There is also one table that gives the averages of colour terms and extinction coefficients for the complete reported period (i.e. P71 to P84). The error there is derived as the standard deviation of the values for each period and may give an indication of the systematic uncertainties. These values should not be used for precise photometric analyses.

Please note that new detectors were installed in July 2010 with increased sensitivity in the infrared and less in the ultraviolet.


P87: April 2011 to September 2011

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 25.937 +/- 0.096 0.082 +/- 0.017 0.346 +/- 0.037 87
B (B-V) 28.118 +/- 0.030 -0.052 +/- 0.004 0.218 +/- 0.005 961
V (B-V) 27.754 +/- 0.029 -0.019 +/- 0.004 0.105 +/- 0.004 768
R (V-R) 27.925 +/- 0.030 -0.085 +/- 0.005 0.070 +/- 0.006 1182
I (V-I) 27.493 +/- 0.039 0.114 +/- 0.004 0.051 +/- 0.006 1438

Quadrant 2

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 25.990 +/- 0.089 0.095 +/- 0.014 0.346 +/- 0.037 85
B (B-V) 28.039 +/- 0.035 -0.034 +/- 0.004 0.218 +/- 0.005 969
V (B-V) 27.793 +/- 0.027 -0.021 +/- 0.003 0.105 +/- 0.004 779
R (V-R) 27.942 +/- 0.038 -0.099 +/- 0.006 0.070 +/- 0.006 1182
I (V-I) 27.553 +/- 0.039 0.130 +/- 0.004 0.051 +/- 0.006 1465

Quadrant 3

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.075 +/- 0.087 0.081 +/- 0.015 0.346 +/- 0.037 91
B (B-V) 28.023 +/- 0.032 -0.069 +/- 0.004 0.218 +/- 0.005 877
V (B-V) 27.695 +/- 0.032 -0.023 +/- 0.004 0.105 +/- 0.004 703
R (V-R) 27.827 +/- 0.040 -0.085 +/- 0.006 0.070 +/- 0.006 1077
I (V-I) 27.478 +/- 0.045 0.137 +/- 0.005 0.051 +/- 0.006 1407

Quadrant 4

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.167 +/- 0.095 0.106 +/- 0.013 0.346 +/- 0.037 91
B (B-V) 28.263 +/- 0.038 -0.086 +/- 0.005 0.218 +/- 0.005 966
V (B-V) 27.799 +/- 0.038 -0.042 +/- 0.005 0.105 +/- 0.004 723
R (V-R) 27.969 +/- 0.033 -0.093 +/- 0.005 0.070 +/- 0.006 1139
I (V-I) 27.518 +/- 0.048 0.094 +/- 0.005 0.051 +/- 0.006 1422

Averages for P71 to P84:

Filter Quadrant Colour Colour Term Ext. coefficient
U 1 (U-B) 0.059 +/- 0.045 0.417 +/- 0.034
U 2 (U-B) 0.061 +/- 0.041 0.417 +/- 0.058
U 3 (U-B) 0.074 +/- 0.042 0.421 +/- 0.034
U 4 (U-B) 0.065 +/- 0.051 0.421 +/- 0.110
B 1 (B-V) -0.069 +/- 0.017 0.214 +/- 0.028
B 2 (B-V) -0.071 +/- 0.014 0.211 +/- 0.019
B 3 (B-V) -0.084 +/- 0.020 0.200 +/- 0.023
B 4 (B-V) -0.085 +/- 0.016 0.212 +/- 0.019
V 1 (B-V) -0.027 +/- 0.019 0.118 +/- 0.019
V 2 (B-V) -0.028 +/- 0.030 0.122 +/- 0.015
V 3 (B-V) -0.034 +/- 0.017 0.105 +/- 0.019
V 4 (B-V) -0.027 +/- 0.012 0.120 +/- 0.012
R 1 (V-R) -0.125 +/- 0.016 0.074 +/- 0.017
R 2 (V-R) -0.135 +/- 0.017 0.076 +/- 0.012
R 3 (V-R) -0.132 +/- 0.025 0.068 +/- 0.013
R 4 (V-R) -0.111 +/- 0.015 0.091 +/- 0.025
I 1 (V-I) 0.046 +/- 0.028 0.041 +/- 0.023
I 2 (V-I) 0.055 +/- 0.026 0.022 +/- 0.010
I 3 (V-I) 0.048 +/- 0.028 0.044 +/- 0.029
I 4 (V-I) 0.049 +/- 0.022 0.040 +/- 0.016

P84: October 2009 to March 2010

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.186 +/- 0.101 0.077 +/- 0.014 0.376 +/- 0.035 133
B (B-V) 28.217 +/- 0.067 -0.056 +/- 0.005 0.238 +/- 0.007 2209
V (B-V) 27.857 +/- 0.037 -0.014 +/- 0.004 0.122 +/- 0.009 1123
R (V-R) 27.899 +/- 0.050 -0.102 +/- 0.008 0.080 +/- 0.007 1570
I (V-I) 26.929 +/- 0.047 0.049 +/- 0.006 0.041 +/- 0.019 990

Quadrant 2

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.340 +/- 0.086 0.079 +/- 0.011 0.376 +/- 0.035 138
B (B-V) 28.045 +/- 0.046 -0.073 +/- 0.003 0.204 +/- 0.008 2032
V (B-V) 27.775 +/- 0.040 -0.026 +/- 0.004 0.124 +/- 0.010 1047
R (V-R) 27.792 +/- 0.044 -0.133 +/- 0.006 0.068 +/- 0.010 1528
I (V-I) 26.881 +/- 0.045 0.063 +/- 0.005 0.028 +/- 0.014 1000

Quadrant 3

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.256 +/- 0.097 0.089 +/- 0.014 0.376 +/- 0.035 131
B (B-V) 28.091 +/- 0.055 -0.075 +/- 0.004 0.207 +/- 0.010 2233
V (B-V) 27.811 +/- 0.029 -0.018 +/- 0.003 0.121 +/- 0.008 1255
R (V-R) 27.813 +/- 0.039 -0.128 +/- 0.006 0.078 +/- 0.007 1317
I (V-I) 26.903 +/- 0.035 0.045 +/- 0.005 0.048 +/- 0.009 1202

Quadrant 4

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.335 +/- 0.090 0.070 +/- 0.013 0.376 +/- 0.035 137
B (B-V) 28.239 +/- 0.060 -0.081 +/- 0.004 0.243 +/- 0.009 2226
V (B-V) 27.832 +/- 0.027 -0.022 +/- 0.002 0.137 +/- 0.008 1530
R (V-R) 27.921 +/- 0.049 -0.100 +/- 0.008 0.124 +/- 0.009 1392
I (V-I) 26.960 +/- 0.042 0.043 +/- 0.005 0.051 +/- 0.021 1341

P83: April 2009 to September 2009

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.334 +/- 0.081 0.082 +/- 0.020 0.436 +/- 0.038 39
B (B-V) 28.191 +/- 0.045 -0.045 +/- 0.005 0.228 +/- 0.007 500
V (B-V) 27.846 +/- 0.029 -0.014 +/- 0.002 0.117 +/- 0.004 734
R (V-R) 27.925 +/- 0.030 -0.134 +/- 0.003 0.081 +/- 0.005 717
I (V-I) 26.886 +/- 0.033 0.104 +/- 0.004 0.013 +/- 0.004 558

Quadrant 2

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.390 +/- 0.064 0.079 +/- 0.015 0.380 +/- 0.031 40
B (B-V) 28.015 +/- 0.041 -0.053 +/- 0.005 0.217 +/- 0.006 427
V (B-V) 27.745 +/- 0.036 -0.031 +/- 0.003 0.107 +/- 0.004 687
R (V-R) 27.808 +/- 0.036 -0.141 +/- 0.004 0.069 +/- 0.004 674
I (V-I) 26.835 +/- 0.027 0.120 +/- 0.003 0.017 +/- 0.004 474

Quadrant 3

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.366 +/- 0.075 0.085 +/- 0.019 0.410 +/- 0.037 38
B (B-V) 28.049 +/- 0.036 -0.048 +/- 0.004 0.180 +/- 0.014 423
V (B-V) 27.811 +/- 0.032 -0.038 +/- 0.002 0.100 +/- 0.008 632
R (V-R) 27.845 +/- 0.036 -0.162 +/- 0.004 0.071 +/- 0.007 601
I (V-I) 26.857 +/- 0.027 0.100 +/- 0.003 0.013 +/- 0.006 446

Quadrant 4

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.425 +/- 0.072 0.101 +/- 0.016 0.414 +/- 0.039 36
B (B-V) 28.183 +/- 0.035 -0.057 +/- 0.004 0.211 +/- 0.008 466
V (B-V) 27.812 +/- 0.028 -0.023 +/- 0.002 0.131 +/- 0.005 672
R (V-R) 27.919 +/- 0.030 -0.128 +/- 0.003 0.101 +/- 0.006 650
I (V-I) 26.920 +/- 0.026 0.106 +/- 0.003 0.044 +/- 0.007 500

P82: November 2008 to March 2009

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.364 +/- 0.095 0.027 +/- 0.095 0.445 +/- 0.053 149
B (B-V) 28.239 +/- 0.051 -0.060 +/- 0.003 0.225 +/- 0.007 3652
V (B-V) 27.900 +/- 0.049 -0.030 +/- 0.004 0.146 +/- 0.003 2053
R (V-R) 27.943 +/- 0.034 -0.114 +/- 0.003 0.102 +/- 0.005 3794
I (V-I) 26.940 +/- 0.038 0.074 +/- 0.003 0.042 +/- 0.005 2803

Quadrant 2

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.521 +/- 0.104 0.025 +/- 0.015 0.484 +/- 0.051 152
B (B-V) 28.072 +/- 0.048 -0.078 +/- 0.003 0.211 +/- 0.005 3490
V (B-V) 27.804 +/- 0.045 -0.033 +/- 0.004 0.133 +/- 0.004 1737
R (V-R) 27.817 +/- 0.047 -0.124 +/- 0.006 0.075 +/- 0.006 2027
I (V-I) 26.862 +/- 0.039 0.084 +/- 0.003 0.010 +/- 0.006 2646

Quadrant 3

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.437 +/- 0.149 0.086 +/- 0.019 0.459 +/- 0.060 169
B (B-V) 28.135 +/- 0.050 -0.089 +/- 0.003 0.200 +/- 0.006 4670
V (B-V) 27.842 +/- 0.044 -0.037 +/- 0.004 0.109 +/- 0.004 1723
R (V-R) 27.821 +/- 0.035 -0.117 +/- 0.003 0.073 +/- 0.005 4781
I (V-I) 26.874 +/- 0.035 0.071 +/- 0.003 0.0 +/- 0.0 3723

Quadrant 4

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.609 +/- 0.107 0.001 +/- 0.012 0.535 +/- 0.056 203
B (B-V) 28.219 +/- 0.049 -0.089 +/- 0.003 0.192 +/- 0.006 5070
V (B-V) 27.825 +/- 0.046 -0.028 +/- 0.004 0.118 +/- 0.004 1795
R (V-R) 27.921 +/- 0.034 -0.096 +/- 0.003 0.110 +/- 0.005 5260
I (V-I) 26.950 +/- 0.038 0.072 +/- 0.004 0.050 +/- 0.006 3828

P81: April 2008 to September 2008

Fixed extinction coefficients for U and I.

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.313 +/- 0.072 0.091 +/- 0.010 0.45 125
B (B-V) 28.119 +/- 0.042 -0.058 +/- 0.006 0.184 +/- 0.003 259
V (B-V) 27.734 +/- 0.040 -0.009 +/- 0.005 0.088 +/- 0.003 416
R (V-R) 27.817 +/- 0.044 -0.152 +/- 0.008 0.057 +/- 0.003 399
I (V-I) 26.916 +/- 0.033 0.013 +/- 0.004 0.05 454

Quadrant 2

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.413 +/- 0.070 0.096 +/- 0.009 0.45 122
B (B-V) 27.955 +/- 0.041 -0.058 +/- 0.006 0.180 +/- 0.003 255
V (B-V) 27.685 +/- 0.033 -0.023 +/- 0.004 0.102 +/- 0.003 413
R (V-R) 27.779 +/- 0.039 -0.167 +/- 0.007 0.087 +/- 0.002 438
I (V-I) 26.882 +/- 0.033 0.030 +/- 0.004 0.05 453

Quadrant 3

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.356 +/- 0.074 0.096 +/- 0.010 0.45 124
B (B-V) 28.046 +/- 0.037 -0.061 +/- 0.005 0.197 +/- 0.003 272
V (B-V) 27.727 +/- 0.032 -0.020 +/- 0.004 0.097 +/- 0.002 404
R (V-R) 27.765 +/- 0.038 -0.156 +/- 0.007 0.070 +/- 0.002 439
I (V-I) 26.883 +/- 0.035 0.025 +/- 0.005 0.05 456

Quadrant 4

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.421 +/- 0.077 0.112 +/- 0.010 0.45 118
B (B-V) 28.110 +/- 0.030 -0.056 +/- 0.004 0.192 +/- 0.003 257
V (B-V) 27.698 +/- 0.031 -0.012 +/- 0.004 0.105 +/- 0.002 391
R (V-R) 27.799 +/- 0.039 -0.134 +/- 0.007 0.066 +/- 0.002 430
I (V-I) 26.895 +/- 0.033 0.025 +/- 0.005 0.05 295

P80: October 2007 to March 2008

Fixed extinction coefficients.

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.352 +/- 0.076 0.055 +/- 0.012 0.45 119
B (B-V) 28.210 +/- 0.036 -0.051 +/- 0.005 0.25 998
V (B-V) 27.858 +/- 0.051 -0.041 +/- 0.005 0.15 1214
R (V-R) 27.879 +/- 0.030 -0.142 +/- 0.005 0.10 797
I (V-I) 26.928 +/- 0.042 0.010 +/- 0.007 0.05 845

Quadrant 2

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.459 +/- 0.072 0.047 +/- 0.011 0.45 126
B (B-V) 28.054 +/- 0.039 -0.048 +/- 0.005 0.25 1111
V (B-V) 27.800 +/- 0.054 -0.045 +/- 0.006 0.15 1275
R (V-R) 27.816 +/- 0.033 -0.142 +/- 0.006 0.10 831
I (V-I) 26.911 +/- 0.048 0.043 +/- 0.007 0.05 1187

Quadrant 3

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.405 +/- 0.084 0.068 +/- 0.012 0.45 130
B (B-V) 28.134 +/- 0.038 -0.055 +/- 0.005 0.25 1028
V (B-V) 27.849 +/- 0.047 -0.054 +/- 0.005 0.15 1335
R (V-R) 27.831 +/- 0.031 -0.146 +/- 0.005 0.10 960
I (V-I) 26.922 +/- 0.043 0.015 +/- 0.007 0.05 853

Quadrant 4

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.487 +/- 0.090 0.041 +/- 0.012 0.45 136
B (B-V) 28.225 +/- 0.044 -0.070 +/- 0.005 0.25 1060
V (B-V) 27.813 +/- 0.051 -0.042 +/- 0.005 0.15 1148
R (V-R) 27.859 +/- 0.035 -0.119 +/- 0.006 0.10 979
I (V-I) 26.929 +/- 0.045 0.035 +/- 0.008 0.05 927

P79: May 2007 to September 2007

Fixed extinction coefficients.

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.383 +/- 0.073 0.132 +/- 0.023 0.45 21
B (B-V) 28.322 +/- 0.030 -0.096 +/- 0.007 0.25 173
V (B-V) 27.952 +/- 0.026 -0.062 +/- 0.006 0.15 212
R (V-R) 27.976 +/- 0.022 -0.149 +/- 0.007 0.10 219
I (V-I) 27.009 +/- 0.022 0.047 +/- 0.007 0.05 77

Quadrant 2

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.477 +/- 0.068 0.126 +/- 0.022 0.45 21
B (B-V) 28.180 +/- 0.034 -0.100 +/- 0.008 0.25 192
V (B-V) 27.881 +/- 0.022 -0.059 +/- 0.005 0.15 220
R (V-R) 27.909 +/- 0.019 -0.141 +/- 0.006 0.10 224
I (V-I) 27.001 +/- 0.026 0.058 +/- 0.008 0.05 91

Quadrant 3

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.415 +/- 0.064 0.135 +/- 0.021 0.45 21
B (B-V) 28.240 +/- 0.032 -0.085 +/- 0.008 0.25 201
V (B-V) 27.925 +/- 0.027 -0.054 +/- 0.006 0.15 220
R (V-R) 27.924 +/- 0.019 -0.156 +/- 0.006 0.10 226
I (V-I) 26.993 +/- 0.019 0.044 +/- 0.006 0.05 86

Quadrant 4

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.488 +/- 0.071 0.137 +/- 0.023 0.45 21
B (B-V) 28.310 +/- 0.022 -0.089 +/- 0.006 0.25 183
V (B-V) 27.882 +/- 0.018 -0.037 +/- 0.004 0.15 198
R (V-R) 27.950 +/- 0.019 -0.120 +/- 0.006 0.10 213
I (V-I) 27.027 +/- 0.020 0.051 +/- 0.007 0.05 74

P78: October 2006 to March 2007

Fixed extinction coefficients for U and I.

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.232 +/- 0.078 0.065 +/- 0.016 0.45 52
B (B-V) 28.069 +/- 0.036 -0.050 +/- 0.006 0.175 +/- 0.007 551
V (B-V) 27.722 +/- 0.037 0.015 +/- 0.004 0.114 +/- 0.005 1238
R (V-R) 27.776 +/- 0.032 -0.109 +/- 0.010 0.059 +/- 0.004 199
I (V-I) 26.876 +/- 0.033 0.086 +/- 0.007 0.05 679

Quadrant 2

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.336 +/- 0.077 0.077 +/- 0.014 0.45 58
B (B-V) 28.005 +/- 0.063 -0.063 +/- 0.012 0.212 +/- 0.006 401
V (B-V) 27.647 +/- 0.061 0.065 +/- 0.006 0.142 +/- 0.005 1186
R (V-R) 27.718 +/- 0.038 -0.089 +/- 0.010 0.093 +/- 0.004 309
I (V-I) 26.893 +/- 0.045 0.071 +/- 0.013 0.05 405

Quadrant 3

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.287 +/- 0.111 0.071 +/- 0.021 0.45 65
B (B-V) 28.013 +/- 0.037 -0.090 +/- 0.006 0.177 +/- 0.010 621
V (B-V) 27.659 +/- 0.035 0.004 +/- 0.003 0.075 +/- 0.006 1450
R (V-R) 27.668 +/- 0.025 -0.092 +/- 0.007 0.041 +/- 0.009 329
I (V-I) 26.841 +/- 0.024 0.077 +/- 0.006 0.05 560

Quadrant 4

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.351 +/- 0.081 0.063 +/- 0.017 0.45 53
B (B-V) 28.159 +/- 0.039 -0.103 +/- 0.005 0.214 +/- 0.005 832
V (B-V) 27.713 +/- 0.039 -0.008 +/- 0.003 0.116 +/- 0.005 1675
R (V-R) 27.781 +/- 0.036 -0.102 +/- 0.011 0.084 +/- 0.005 196
I (V-I) 26.883 +/- 0.041 0.073 +/- 0.008 0.05 967

P77: April 2006 to September 2006

Fixed extinction coefficients.

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.283 +/- 0.068 0.107 +/- 0.017 0.45 42
B (B-V) 28.281 +/- 0.029 -0.063 +/- 0.007 0.25 215
V (B-V) 27.922 +/- 0.021 -0.049 +/- 0.005 0.15 251
R (V-R) 27.913 +/- 0.027 -0.120 +/- 0.010 0.10 247
I (V-I) 26.989 +/- 0.021 0.020 +/- 0.007 0.05 103

Quadrant 2

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.407 +/- 0.067 0.107 +/- 0.016 0.45 44
B (B-V) 28.194 +/- 0.037 -0.076 +/- 0.009 0.25 239
V (B-V) 27.896 +/- 0.026 -0.059 +/- 0.006 0.15 255
R (V-R) 27.878 +/- 0.025 -0.142 +/- 0.009 0.10 251
I (V-I) 26.973 +/- 0.038 0.012 +/- 0.013 0.05 108

Quadrant 3

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.336 +/- 0.075 0.103 +/- 0.018 0.45 40
B (B-V) 28.183 +/- 0.040 -0.083 +/- 0.009 0.25 255
V (B-V) 27.845 +/- 0.030 -0.034 +/- 0.009 0.15 120
R (V-R) 27.822 +/- 0.028 -0.138 +/- 0.010 0.10 263
I (V-I) 26.940 +/- 0.033 -0.007 +/- 0.013 0.05 103

Quadrant 4

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.431 +/- 0.073 0.139 +/- 0.017 0.45 34
B (B-V) 28.277 +/- 0.027 -0.071 +/- 0.006 0.25 227
V (B-V) 27.851 +/- 0.024 -0.019 +/- 0.007 0.15 102
R (V-R) 27.882 +/- 0.030 -0.112 +/- 0.011 0.10 245
I (V-I) 26.970 +/- 0.028 0.029 +/- 0.010 0.05 96

P76: November 2005 to March 2006

Fixed extinction coefficients.

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.426 +/- 0.104 0.057 +/- 0.016 0.45 94
B (B-V) 28.313 +/- 0.043 -0.090 +/- 0.005 0.25 906
V (B-V) 27.935 +/- 0.042 -0.034 +/- 0.005 0.15 766
R (V-R) 27.978 +/- 0.042 -0.134 +/- 0.011 0.10 286
I (V-I) 26.995 +/- 0.078 0.045 +/- 0.018 0.05 466

Quadrant 2

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.516 +/- 0.090 0.061 +/- 0.013 0.45 113
B (B-V) 28.171 +/- 0.039 -0.070 +/- 0.005 0.25 796
V (B-V) 27.879 +/- 0.029 -0.029 +/- 0.003 0.15 1008
R (V-R) 27.917 +/- 0.067 -0.144 +/- 0.019 0.10 224
I (V-I) 26.989 +/- 0.062 0.048 +/- 0.014 0.05 433

Quadrant 3

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.427 +/- 0.142 0.116 +/- 0.018 0.45 128
B (B-V) 28.193 +/- 0.039 -0.096 +/- 0.004 0.25 1275
V (B-V) 27.879 +/- 0.033 -0.041 +/- 0.003 0.15 1439
R (V-R) 27.880 +/- 0.055 -0.154 +/- 0.014 0.10 341
I (V-I) 26.947 +/- 0.042 0.046 +/- 0.008 0.05 724

Quadrant 4

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.535 +/- 0.132 0.060 +/- 0.015 0.45 141
B (B-V) 28.319 +/- 0.043 -0.096 +/- 0.004 0.25 1741
V (B-V) 27.898 +/- 0.038 -0.038 +/- 0.003 0.15 1796
R (V-R) 27.968 +/- 0.046 -0.130 +/- 0.012 0.10 376
I (V-I) 27.009 +/- 0.040 0.053 +/- 0.007 0.05 1183

P75: April 2005 to September 2005

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.200 +/- 0.074 0.099 +/- 0.010 0.403 +/- 0.043 111
B (B-V) 28.198 +/- 0.033 -0.066 +/- 0.005 0.236 +/- 0.008 617
V (B-V) 27.819 +/- 0.031 -0.020 +/- 0.004 0.123 +/- 0.007 368
R (V-R) 27.857 +/- 0.022 -0.122 +/- 0.006 0.064 +/- 0.003 284
I (V-I) 26.958 +/- 0.030 0.030 +/- 0.006 0.069 +/- 0.017 186

Quadrant 2

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.295 +/- 0.075 0.102 +/- 0.009 0.387 +/- 0.040 132
B (B-V) 28.060 +/- 0.036 -0.057 +/- 0.005 0.239 +/- 0.009 570
V (B-V) 27.756 +/- 0.033 -0.014 +/- 0.004 0.126 +/- 0.009 506
R (V-R) 27.786 +/- 0.026 -0.122 +/- 0.007 0.064 +/- 0.004 316
I (V-I) 26.911 +/- 0.033 0.046 +/- 0.006 0.032 +/- 0.012 262

Quadrant 3

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.200 +/- 0.085 0.094 +/- 0.011 0.393 +/- 0.048 130
B (B-V) 28.078 +/- 0.032 -0.077 +/- 0.004 0.240 +/- 0.007 792
V (B-V) 27.762 +/- 0.025 -0.018 +/- 0.003 0.130 +/- 0.004 533
R (V-R) 27.750 +/- 0.022 -0.098 +/- 0.006 0.072 +/- 0.003 378
I (V-I) 26.893 +/- 0.027 0.038 +/- 0.004 0.070 +/- 0.012 257

Quadrant 4

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.244 +/- 0.086 0.095 +/- 0.010 0.315 +/- 0.042 132
B (B-V) 28.188 +/- 0.041 -0.082 +/- 0.004 0.220 +/- 0.005 921
V (B-V) 27.763 +/- 0.031 -0.017 +/- 0.004 0.115 +/- 0.003 600
R (V-R) 27.820 +/- 0.023 -0.088 +/- 0.005 0.063 +/- 0.002 425
I (V-I) 26.899 +/- 0.029 0.044 +/- 0.005 0.016 +/- 0.009 271

P74: October 2004 to March 2005

Fixed extinction coefficients.

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.352 +/- 0.103 0.054 +/- 0.010 0.45 243
B (B-V) 28.213 +/- 0.030 -0.081 +/- 0.005 0.25 518
V (B-V) 27.820 +/- 0.028 -0.021 +/- 0.003 0.15 863
R (V-R) 27.867 +/- 0.029 -0.119 +/- 0.008 0.10 487
I (V-I) 26.948 +/- 0.028 0.047 +/- 0.004 0.05 1780

Quadrant 2

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.317 +/- 0.147 0.032 +/- 0.013 0.45 264
B (B-V) 28.072 +/- 0.040 -0.078 +/- 0.007 0.25 494
V (B-V) 27.777 +/- 0.060 -0.020 +/- 0.007 0.15 819
R (V-R) 27.841 +/- 0.061 -0.133 +/- 0.019 0.10 401
I (V-I) 26.933 +/- 0.042 0.048 +/- 0.006 0.05 1407

Quadrant 3

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.337 +/- 0.141 0.066 +/- 0.013 0.45 276
B (B-V) 28.107 +/- 0.037 -0.106 +/- 0.005 0.25 830
V (B-V) 27.781 +/- 0.027 -0.031 +/- 0.003 0.15 1320
R (V-R) 27.779 +/- 0.024 -0.123 +/- 0.007 0.10 555
I (V-I) 26.882 +/- 0.026 0.066 +/- 0.003 0.05 2301

Quadrant 4

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.449 +/- 0.129 0.047 +/- 0.010 0.45 323
B (B-V) 28.226 +/- 0.030 -0.103 +/- 0.003 0.25 961
V (B-V) 27.783 +/- 0.028 -0.024 +/- 0.003 0.15 1336
R (V-R) 27.860 +/- 0.026 -0.111 +/- 0.007 0.10 575
I (V-I) 26.970 +/- 0.049 0.050 +/- 0.005 0.05 2954

P73: April 2004 to September 2004

Fixed extinction coefficients.

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.431 +/- 0.077 0.008 +/- 0.016 0.45 87
B (B-V) 28.137 +/- 0.033 -0.075 +/- 0.005 0.25 502
V (B-V) 27.925 +/- 0.024 -0.034 +/- 0.003 0.15 490
R (V-R) 27.962 +/- 0.043 -0.119 +/- 0.016 0.10 136
I (V-I) 27.030 +/- 0.044 0.021 +/- 0.014 0.05 127

Quadrant 2
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.359 +/- 0.075 0.028 +/- 0.013 0.45 92
B (B-V) 28.194 +/- 0.029 -0.075 +/- 0.005 0.25 483
V (B-V) 27.923 +/- 0.026 -0.035 +/- 0.004 0.15 540
R (V-R) 27.959 +/- 0.038 -0.141 +/- 0.010 0.10 296
I (V-I) 27.025 +/- 0.040 0.031 +/- 0.009 0.05 279

Quadrant 3
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.414 +/- 0.086 0.032 +/- 0.016 0.45 95
B (B-V) 28.193 +/- 0.026 -0.090 +/- 0.004 0.25 496
V (B-V) 27.881 +/- 0.023 -0.045 +/- 0.003 0.15 513
R (V-R) 27.877 +/- 0.034 -0.138 +/- 0.010 0.10 263
I (V-I) 26.954 +/- 0.034 0.036 +/- 0.010 0.05 144

Quadrant 4
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.509 +/- 0.094 0.056 +/- 0.014 0.45 100
B (B-V) 28.333 +/- 0.023 -0.087 +/- 0.003 0.25 435
V (B-V) 27.919 +/- 0.023 -0.038 +/- 0.003 0.15 466
R (V-R) 28.000 +/- 0.029 -0.117 +/- 0.008 0.10 309
I (V-I) 27.061 +/- 0.037 0.034 +/- 0.10 0.05 260


P72: October 2003 to February 2004

Fixed extinction coefficients.

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.314 +/- 0.085 0.014 +/- 0.011 0.45 132
B (B-V) 28.161 +/- 0.039 -0.095 +/- 0.003 0.25 2352
V (B-V) 27.772 +/- 0.026 -0.037 +/- 0.002 0.15 1998
R (V-R) 27.823 +/- 0.027 -0.131 +/- 0.004 0.10 1304
I (V-I) 26.899 +/- 0.050 0.058 +/- 0.008 0.05 1102

Quadrant 2
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.334 +/- 0.087 0.017 +/- 0.012 0.45 134
B (B-V) 28.029 +/- 0.044 -0.087 +/- 0.004 0.25 2133
V (B-V) 27.722 +/- 0.032 -0.036 +/- 0.003 0.15 1899
R (V-R) 27.753 +/- 0.034 -0.140 +/- 0.006 0.10 986
I (V-I) 26.828 +/- 0.029 0.057 +/- 0.006 0.05 617

Quadrant 3

Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.288 +/- 0.110 0.033 +/- 0.014 0.45 145
B (B-V) 28.032 +/- 0.047 -0.121 +/- 0.003 0.25 3061
V (B-V) 27.713 +/- 0.030 -0.060 +/- 0.002 0.15 2261
R (V-R) 27.709 +/- 0.033 -0.154 +/- 0.005 0.10 1297
I (V-I) 26.812 +/- 0.033 0.046 +/- 0.005 0.05 1261

Quadrant 4
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.400 +/- 0.097 0.026 +/- 0.010 0.45 180
B (B-V) 28.178 +/- 0.046 -0.106 +/- 0.003 0.25 3576
V (B-V) 27.760 +/- 0.037 -0.047 +/- 0.002 0.15 2598
R (V-R) 27.824 +/- 0.038 -0.116 +/- 0.005 0.10 1784
I (V-I) 26.933 +/- 0.041 0.025 +/- 0.006 0.05 1493


P71: April 2003 to August 2003

Fixed extinction coefficients.

Quadrant 1
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.544 +/- 0.098 -0.038 +/- 0.028 0.45 25
B (B-V) 28.360 +/- 0.037 -0.077 +/- 0.005 0.25 576
V (B-V) 27.965 +/- 0.004 -0.030 +/- 0.004 0.15 562
R (V-R) 27.982 +/- 0.022 -0.102 +/- 0.006 0.10 377
I (V-I) 27.050 +/- 0.025 0.037 +/- 0.008 0.05 361

Quadrant 2
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.516 +/- 0.094 -0.020 +/- 0.023 0.45 37
B (B-V) 28.188 +/- 0.044 -0.076 +/- 0.007 0.25 492
V (B-V) 27.865 +/- 0.031 -0.040 +/- 0.004 0.15 539
R (V-R) 27.871 +/- 0.028 -0.130 +/- 0.008 0.10 374
I (V-I) 26.970 +/- 0.027 0.056 +/- 0.008 0.05 325

Quadrant 3
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.498 +/- 0.092 -0.032 +/- 0.027 0.45 24
B (B-V) 28.209 +/- 0.041 -0.094 +/- 0.007 0.25 488
V (B-V) 27.872 +/- 0.029 -0.033 +/- 0.005 0.15 472
R (V-R) 27.847 +/- 0.028 -0.090 +/- 0.010 0.10 263
I (V-I) 26.960 +/- 0.026 0.071 +/- 0.010 0.05 264

Quadrant 4
Filter Colour Zero Point Colour Term Ext. coefficient N. of stars
U (U-B) 26.625 +/- 0.091 -0.043 +/- 0.023 0.45 34
B (B-V) 28.378 +/- 0.039 -0.095 +/- 0.006 0.25 581
V (B-V) 27.937 +/- 0.027 -0.028 +/- 0.004 0.15 584
R (V-R) 27.982 +/- 0.024 -0.087 +/- 0.008 0.10 309
I (V-I) 27.072 +/- 0.025 0.051 +/- 0.008 0.05 321



 
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