La Silla Facilities

Photometric Zero Points for EFOSC2 with CCD#40: Full Summary

Note that this page is here for historic interest only, and it is no longer updated. See the EFOSC2 Zero-point page for current values.

Until June 2000 the mean La Silla extinction values have been used for computing the coefficients.
From July 2001 the extinction values have been fitted as a free parameter as well.

U = u + ZP(u) + (U-B)* col(u) - Ext(u)*Airmass
B = b + ZP(b) + (B-V)* col(b) - Ext(b)*Airmass
V = v + ZP(v) + (B-V)* col(v) - Ext(v)*Airmass
R = r + ZP(r) + (V-R)* col(r) - Ext(r)*Airmass
I = i + ZP(i) + (V-R)* col(i) - Ext(i)*Airmass

Note to observers: you can help us to maintain this database by sending your measurements. All contributions will be acknowledged.

February 21th, 1998

The data has been obtained during a photometric night. The telescope was closed at the end of the night because of to strong wind. The determinations are made from only 1 standard stars (RU_149).

Filters	Zero point	Color term
U	24.129	0.063
B	25.934	0.031
V	25.961	0.024
R	26.031	-0.003

March 19th, 1998

The data has been obtained during a non-photometric night (some cirrus at the beginning, but the second half part was quiet cloudy). The determinations are made from only 1 standard stars (PG0942-02).

Filters	Zero point	Color term
U	24.102	-0.019
B	25.945	-0.052
V	25.986	0.050
R	26.066	-0.050
I	25.259	-0.079

April 18th, 1998

The data has been obtained during a partial photometric night (only the first half part). The determinations are made from 3 standard stars (RU_149, PG1047+003, PG1323-086 2 times). All the 4 measurements are in very good agreement.

Filters	Zero point	Color term
U	24.356 +/- 0.015	0.059 +/- 0.005
B	25.899 +/- 0.010	0.045 +/- 0.005
V	26.023 +/- 0.007	0.037 +/- 0.005
R	26.132 +/- 0.015	0.025 +/- 0.020
I	25.294 +/- 0.020	-0.036 +/- 0.050

August 24th, 1998

The data has been obtained during a non-photometric night (absoption of about ~0.2 but constant in all filters). The determinations are made from 1 standard stars (Tphe).

Filters	Zero point	Color term
U	24.113	0.053
B	25.680	0.052
V	25.871	0.024
R	25.981	0.014
I	25.100	-0.044

August 26th, 1998

The data has been obtained during a perfectly photometric night. The determinations are made from 3 standard stars (Tphe, PG2331+05, Mark A 2 times). All the 4 measurements are in very good agreement.

Filters	Zero point	Color term
U	24.315 +/- 0.025	0.056 +/- 0.008
B	25.870 +/- 0.010	0.037 +/- 0.005
V	25.956 +/- 0.010	0.040 +/- 0.006
R	26.070 +/- 0.015	0.025 +/- 0.008
I	25.220 +/- 0.010	-0.018 +/- 0.015

August 28th, 1998

The data has been obtained during a perfectly photometric night. The determinations are made from 2 standard stars (Tphe, PG2331+05).

Filters	Zero point	Color term
U	24.268 +/- 0.015	0.045 +/- 0.020
B	25.853 +/- 0.020	0.020 +/- 0.015
V	25.951 +/- 0.020	0.032 +/- 0.010
R	26.060 +/- 0.015	0.027 +/- 0.015
I	25.215 +/- 0.015	-0.010 +/- 0.025

August 29th, 1998

The data has been obtained during a perfectly photometric night. The determinations are made from 1 standard stars (Mark A).

Filters	Zero point	Color term
U	24.286	0.042
B	25.931	0.037
V	25.963	0.046
R	26.071	0.027
I	25.203	-0.006

Note that the Primary mirror (M1) has been washed beginning of December. Measurements shown that the reflectivity increase by about 5% (from 85% to 90%)

December 18th, 1998

The data has been obtained during a non-photometric night. For the 2 first standards the cirrus were very thin but for the third standard PG0918+02 the absorption was greater ... of the order of 0.2-0.3 magnitude. The determinations are made from 2 standard stars (Rubin149, Rubin152 and PG0918+02), each star observed 3 times with 3 different CCD places and 3 exposure times.

Filters	Zero point	Color term
U	24.237 +/- 0.030	0.057 +/- 0.020
B	25.882 +/- 0.020	0.040 +/- 0.015
V	25.950 +/- 0.020	0.045 +/- 0.015
R	26.100 +/- 0.020	0.005 +/- 0.015
I	25.245 +/- 0.030	-0.017 +/- 0.030

From the January 12th, 1999 measurements we should certainly add 0.05-0.10 magnitude to all the these values, the absorption seems no negligeable as a thought first at all.

January 12th, 1999

The data has been obtained during a perfectly photometric night. The determinations are made from 3 standard stars (Rubin149, Rubin152 and PG0918+02), each star observed 3 times with 3 different CCD places and 3 exposure times.

Filters	Zero point	Color term
U	24.296 +/- 0.030	0.055 +/- 0.015
B	25.939 +/- 0.016	0.053 +/- 0.015
V	26.002 +/- 0.020	0.037 +/- 0.010
R	26.114 +/- 0.012	0.025 +/- 0.025
I	25.282 +/- 0.025	-0.010 +/- 0.030

These measurements are in perfect agreement with a measured reflectivity increase of 5% after mirror washing.

February 7th, 1999

March 11th, 1999

Not a photometric night ... raining !!

April 8th, 1999

The data has been obtained during a perfectly photometric night. The determinations are made from 4 standard stars (Rubin149, Rubin152, PG0942-029 and PG1633+099), each star observed 3 times at 3 different CCD places and with 3 exposure times.

Filters	Zero point	Color term
U	24.229 +/- 0.030	0.059 +/- 0.013
B	25.930 +/- 0.016	0.032 +/- 0.016
V	25.972 +/- 0.018	0.043 +/- 0.010
R	26.076 +/- 0.016	0.011 +/- 0.015
I	25.238 +/- 0.022	-0.023 +/- 0.014

June 06th, 1999

The data has been obtained during a perfectly photometric night. The determinations are made from 3 standard stars (Mark A, PG 2213 and Tphe), each star observed 3 times at 3 different CCD places and with 3 exposure times.

Filters	Zero point	Color term
U	24.241 +/- 0.007	+0.035 +/- 0.025
B	25.952 +/- 0.004	+0.020 +/- 0.014
V	25.980 +/- 0.003	+0.020 +/- 0.014
R	26.079 +/- 0.003	+0.013 +/- 0.009
I	25.231 +/- 0.003	+0.021 +/- 0.015

July 28th, 1999

The data has been obtained during a perfectly photometric night. The determinations are made from 3 standard stars (PG 1657, Mark A and PG 2213), each star observed 3 times at 3 different CCD places and with 3 exposure times.

Filters	Zero point	Color term
U	24.213 +/- 0.011	+0.026 +/- 0.018
B	25.959 +/- 0.003	+0.040 +/- 0.028
V	25.968 +/- 0.002	+0.023 +/- 0.016
R	26.061 +/- 0.007	-0.007 +/- 0.014
I	25.225 +/- 0.005	-0.017 +/- 0.012

August 16th, 1999

The data has been obtained during a perfectly photometric night. The determinations are made from 3 standard stars (PG 1323, PG 2213 and T Phe), each star observed 3 times at 3 different CCD places and with 3 exposure times.

Filters	Zero point	Color term
B	25.934 +/- 0.003	+0.049 +/- 0.035
V	25.961 +/- 0.002	+0.032 +/- 0.023
R	26.060 +/- 0.002	+0.022 +/- 0.016
I	25.243 +/- 0.004	-0.060 +/- 0.043

August 17th, 1999

The data has been obtained during a partialy photometric night (1rst part). The determinations are made from 2 standard stars (PG 1530 and SA 110), each star observed 3 times at 3 different CCD places and with 3 exposure times.

Filters	Zero point	Color term
U	24.174 +/- 0.008	+0.086 +/- 0.061
B	25.940 +/- 0.002	+0.035 +/- 0.025
V	25.951 +/- 0.002	+0.042 +/- 0.030
R	26.053 +/- 0.002	+0.026 +/- 0.018
I	25.254 +/- 0.007	-0.067 +/- 0.049

Mirror washing beginning of September.

September 13th, 1999

The data has been obtained during a partialy photometric night, cirrus at the end. The determinations are made from 2 standard stars (), each star observed 3 times at 3 different CCD places and with 3 exposure times. A constant absorption of 0.40 can be extrpolated !

Filters	Zero point	Color term
U	23.987 +/- 0.021	+0.036 +/- 0.026
B	25.630 +/- 0.018	+0.040 +/- 0.028
V	25.650 +/- 0.015	+0.055 +/- 0.039
R	25.741 +/- 0.012	+0.012 +/- 0.013
I	24.920 +/- 0.022	-0.021 +/- 0.015

September 14th, 1999

The data has been obtained during a perfectly photometric night. The determinations are made from 1 standard stars (), each star observed 3 times at 3 different CCD places and with 3 exposure times.

Filters	Zero point	Color term
B	26.022 +/- 0.029	+0.005 +/- 0.020
V	26.066 +/- 0.023	+0.033 +/- 0.020
R	26.166 +/- 0.005	+0.010 +/- 0.020

September 15th, 1999

The data has been obtained during a perfectly photometric night. The determinations are made from 1 standard stars (), each star observed 3 times at 3 different CCD places and with 3 exposure times.

Filters	Zero point	Color term
B	25.998 +/- 0.014	+0.005 +/- 0.020
V	26.045 +/- 0.012	+0.031 +/- 0.020
R	26.161 +/- 0.010	+0.011 +/- 0.020

September 16th, 1999

Filters	Zero point	Color term
U	24.243 +/- 0.008	+0.042 +/- 0.030
B	26.004 +/- 0.002	+0.043 +/- 0.030
V	26.020 +/- 0.002	+0.039 +/- 0.028
R	26.113 +/- 0.002	+0.016 +/- 0.011
I	25.289 +/- 0.003	-0.012 +/- 0.008

September 17th, 1999

The data has been obtained during a perfectly photometric night. The determinations are made from 1 standard star (PG 2213), the star observed 3 times at 3 different CCD places and with 3 exposure times.

Filters	Zero point	Color term
U	24.249 +/- 0.005	+0.062 +/- 0.044
B	25.990 +/- 0.002	+0.027 +/- 0.019
V	26.019 +/- 0.003	+0.024 +/- 0.017
R	26.121 +/- 0.002	+0.023 +/- 0.016
I	25.287 +/- 0.003	+0.014 +/- 0.010

November 1st, 1999

The data has been obtained during a "almost" perfectly photometric night (some clouds near the horizon). NOTE that at the beginning of the previous night it snow in La Silla (~5cm). The determinations are made from 3 standard stars (MARK_A, PG 2213, TPHE), each stars observed 3 times at 3 different CCD places and with 3 exposure times.

Filters	Zero point	Color term
U	24.231 +/- 0.007	+0.042 +/- 0.030
B	25.973 +/- 0.003	+0.020 +/- 0.014
V	25.991 +/- 0.002	+0.017 +/- 0.012
R	26.088 +/- 0.002	+0.001 +/- 0.003
I	25.248 +/- 0.004	-0.029 +/- 0.021

December 3rd, 1999

The data has been obtained during a perfectly photometric night (very good seeing ~0.6-0.7"). The determinations are made from 3 standard stars (TPHE, PG0231, RUBIN_149), each stars observed 3 times at 3 different CCD places and with 3 exposure times.

Filters	Zero point	Color term
U	24.218 +/- 0.007	+0.070 +/- 0.049
B	25.961 +/- 0.002	+0.040 +/- 0.028
V	25.991 +/- 0.002	+0.033 +/- 0.023
R	26.095 +/- 0.001	+0.022 +/- 0.016
I	25.249 +/- 0.005	-0.046 +/- 0.032

January 2nd, 2000

A photometric night. Data obtained from (Landolt) standard star fields TPHE and RU152 (3 sets of observations, each with 3 exposures in every band).

Filters	Zero point	Color term
U	23.959 +/- 0.010	0.055 +/- 0.012
B	25.905 +/- 0.006	0.046 +/- 0.010
V	25.962 +/- 0.003	0.030 +/- 0.004
R	26.023 +/- 0.005	0.030 +/- 0.016
i	25.256 +/- 0.005	-0.033 +/- 0.014

February 29th, 2000

A photometric night. Data obtained from (Landolt) standard star fields RU152 and PG1323 (4 sets of observations, each with 3 exposures in every band)

Filters	Zero point	Color term
U	23.864 +/- 0.010	0.087 +/- 0.018
B	25.839 +/- 0.004	0.053 +/- 0.008
V	25.890 +/- 0.005	0.059 +/- 0.020
R	25.989 +/- 0.008	0.050 +/- 0.030
i	25.182 +/- 0.013	0.028 +/- 0.052

March 23-28th, 2000

Aluminization of the 3.60m telescope M1 mirror

March 29-30th, 2000
The data has been obtained during 2 photometric night (good seeing ~1.0") ... No clouds apparent, but it seems that the haze observed was producing some absorption (0.050 between the 2 nights at least). The determinations are made from 3 standard stars (PG1047,PG1323 and PG1525), one observed 4 times, each stars observed 3 times at 3 different CCD places and with 3 exposure times.

Filters	Zero point	Color term
29/03/2000 (1 observations)
B	26.013 +/- 0.003	+0.028 +/- 0.019
V	26.036 +/- 0.004	+0.015 +/- 0.011
R	26.113 +/- 0.002	+0.008 +/- 0.006
I	25.244 +/- 0.002	-0.035 +/- 0.024
30/03/2000 (5 observations)
U	24.207 +/- 0.002	+0.072 +/- 0.051
B	25.968 +/- 0.002	+0.026 +/- 0.018
V	25.978 +/- 0.002	+0.025 +/- 0.018
R	26.053 +/- 0.002	+0.025 +/- 0.017
I	25.210 +/- 0.005	-0.031 +/- 0.022

June 26-27th, 2000

Problem of response found ... CCD40 was dismounted and again UV floaded

June 29th, 2000
A photometric night (clouds during the 2 first hours ... After a snow storm). Data obtained from (Landolt) standard star fields PG2213, PG2336 (2 times) and Tphe (each with 3 exposures in every band)

Filters	Zero point	Color term
U	24.256 +/- 0.004	+0.051 +/- 0.036
B	26.005 +/- 0.003	+0.025 +/- 0.018
V	26.028 +/- 0.003	+0.021 +/- 0.015
R	26.109 +/- 0.004	+0.028 +/- 0.019
i	25.263 +/- 0.007	-0.023 +/- 0.016

July 20th, 2001

Setup night. The weather turned unphotometric after or during the observations. The range of airmass observed was small, thus the extinction term has large errors. Many stars in the R and I images were saturated, contributing to the errors. There was a bug with the headers- so no airmass or siderial time info available, and had to be calculated from the UT, so the airmass may not be very accurate. Nevertheless, these values agree well with previous values. The Landolt standard star fields PG1525 and SA110 were observed.

Note: The extinction term has been fitted as a free parameter too.

Filters	Zero point	Extinction	Color term
U #640	23.736 +/- 0.213	0.112 +/- 0.172	+0.047 +/- 0.013
B #639	25.858 +/- 0.409	0.150 +/- 0.310	+0.045 +/- 0.029
V #641	26.247 +/- 0.436	0.278 +/- 0.328	+0.040 +/- 0.041
R #642	26.167 +/- 0.140	0.097 +/- 0.105	+0.027 +/- 0.021
i #705	25.234 +/- 0.996	-0.008 +/- 0.730	+0.036 +/- 0.087

Jan 11th, 2001

Setup night. The sky was a little hazy and humidity was high. The Landolt standard star fields Rubin149 (centered on C), PG1047 (centred on A) and PG1323 (centred on A) were observed. Because the zeropoints are all about 0.3 mag lower than the usual values, the night is not photometric.
Note: The extinction term has been fitted as a free parameter too.

Filters	Zero point	Extinction	Color term
U #640	23.663 +/- 0.068	0.424 +/- 0.048	0.050 +/- 0.021
B #639	25.573 +/- 0.046	0.174 +/- 0.030	0.024 +/- 0.019
V #641	25.668 +/- 0.061	0.088 +/- 0.039	0.002 +/- 0.025
R #642	25.711 +/- 0.042	0.024 +/- 0.028	-0.016 +/- 0.032
i #705	24.902 +/- 0.044	0.002 +/- 0.031	-0.021 +/- 0.019

Feb 12th, 2001

Setup night. The sky is clear throughout the night, and likely photometric. The Landolt standard star fields Rubin149 (centered on C), PG1047 (centred on A) and PG1323 (centred on A) were observed.