4 Cross-identifications and astrometry

 

 

Table 5: UBVRI photometry of several Landolt standard stars. Columns give the star identifier, our photometric data (magnitude V and colour indexes B-V, U-B, V-R and V-I) with their standard errors and, in the last columns, the number of observational runs (N_r) and the number of measurements (N_m) used for each star in each band (V, B, U, R and I, in this order)

star	V	B-V	U-B	V-R	V-I	$N_{\rm r}$	$N_{\rm m}$	$N_{\rm r}$	$N_{\rm m}$	$N_{\rm r}$	$N_{\rm m}$	$N_{\rm r}$	$N_{\rm m}$	$N_{\rm r}$	$N_{\rm m}$
44 028	11.329$\pm$0.002	0.726$\pm$0.001	0.200$\pm$0.004	0.394$\pm$0.001	0.764$\pm$0.002	4	30	4	16	4	34	4	23	4	35
44 113	11.713$\pm$0.006	1.206$\pm$0.002	0.996$\pm$0.019	0.667$\pm$0.003	1.229$\pm$0.005	1	9	1	7	1	10	1	7	1	9
76 280	12.670$\pm$0.004	0.925$\pm$0.006	0.728$\pm$0.015	0.531$\pm$0.004	0.989$\pm$0.002	3	16	3	15	3	14	3	12	2	8
76 281	12.235$\pm$0.001	0.537$\pm$0.003	-0.015$\pm$0.007	0.301$\pm$0.003	0.588$\pm$0.007	3	8	3	12	3	14	3	11	3	12
93 103	8.834$\pm$0.001	1.179$\pm$0.001	1.182$\pm$0.001	0.582$\pm$0.001	1.103$\pm$0.002	2	3	2	3	2	3	2	3	3	4
95 016	14.306$\pm$0.010	1.287$\pm$0.008	---	0.802$\pm$0.006	1.483$\pm$0.008	1	4	1	4	0	0	1	4	1	4
95 096	9.995$\pm$0.001	0.155$\pm$0.001	0.041$\pm$0.001	0.085$\pm$0.001	0.190$\pm$0.001	2	3	2	3	2	3	2	3	2	3
96 405	10.664$\pm$0.005	1.291$\pm$0.007	1.505$\pm$0.008	0.653$\pm$0.002	1.214$\pm$0.004	3	12	3	13	3	11	3	12	3	14
96 406	9.296$\pm$0.003	0.213$\pm$0.002	0.125$\pm$0.004	0.116$\pm$0.005	0.242$\pm$0.005	3	11	3	10	3	15	3	15	3	15
98 185	10.544$\pm$0.002	0.187$\pm$0.003	0.108$\pm$0.003	0.118$\pm$0.004	0.247$\pm$0.003	3	12	3	12	3	9	3	14	3	11
98 193	10.021$\pm$0.002	1.166$\pm$0.005	1.170$\pm$0.005	0.613$\pm$0.003	1.153$\pm$0.003	3	8	3	14	3	9	3	13	3	11
98 650	12.277$\pm$0.003	0.157$\pm$0.004	0.121$\pm$0.006	0.076$\pm$0.002	0.175$\pm$0.005	4	18	4	18	3	18	3	15	3	18
98 653	9.533$\pm$0.001	0.024$\pm$0.002	-0.119$\pm$0.001	-0.003$\pm$0.003	0.012$\pm$0.001	2	3	2	3	3	3	4	14	3	3
98 667	8.382$\pm$0.001	0.041$\pm$0.003	-0.337$\pm$0.009	0.083$\pm$0.007	0.170$\pm$0.005	2	3	4	10	3	11	3	14	3	12
98 670	11.930$\pm$0.002	1.351$\pm$0.007	1.335$\pm$0.008	0.722$\pm$0.002	1.371$\pm$0.001	4	20	4	22	3	18	3	17	3	13
98 671	13.385$\pm$0.003	0.963$\pm$0.003	0.800$\pm$0.013	0.576$\pm$0.002	1.066$\pm$0.005	3	15	3	14	3	17	3	16	3	19
98 682	13.747$\pm$0.002	0.653$\pm$0.006	0.104$\pm$0.019	0.361$\pm$0.005	0.696$\pm$0.006	3	9	3	13	3	16	3	17	3	15
98 685	11.945$\pm$0.003	0.488$\pm$0.005	0.050$\pm$0.019	0.283$\pm$0.004	0.566$\pm$0.004	2	14	2	12	2	16	2	16	2	14
99 438	9.395$\pm$0.006	-0.164$\pm$0.005	-0.645$\pm$0.014	-0.059$\pm$0.003	-0.136$\pm$0.003	2	7	2	5	2	8	2	7	1	6
99 447	9.395$\pm$0.003	-0.060$\pm$0.003	-0.210$\pm$0.007	-0.036$\pm$0.002	-0.063$\pm$0.004	1	5	1	4	1	6	1	5	1	6
100 267	13.035$\pm$0.003	0.492$\pm$0.003	-0.049$\pm$0.013	0.310$\pm$0.005	0.610$\pm$0.003	2	8	2	10	2	10	2	8	2	10
100 269	12.367$\pm$0.003	0.550$\pm$0.006	-0.006$\pm$0.009	0.340$\pm$0.004	0.662$\pm$0.002	2	7	2	9	2	9	2	8	2	10
113 274	8.824$\pm$0.001	0.484$\pm$0.002	0.012$\pm$0.002	0.279$\pm$0.002	0.547$\pm$0.004	2	3	2	8	1	6	2	7	2	9
113 276	9.065$\pm$0.001	0.653$\pm$0.003	0.189$\pm$0.004	0.361$\pm$0.001	0.684$\pm$0.005	2	3	2	7	3	10	2	3	2	9
114 750	11.926$\pm$0.006	-0.058$\pm$0.005	-0.314$\pm$0.011	0.029$\pm$0.001	-0.027$\pm$0.003	3	8	4	10	4	13	3	3	2	3
GD 71	13.035$\pm$0.002	-0.243$\pm$0.004	-1.083$\pm$0.008	-0.134$\pm$0.002	-0.314$\pm$0.002	2	34	2	34	2	32	2	33	2	30

 

 

Table 6: Individual differences among Landolt's data and our photometry in the sense this work-minus- Landolt

star	V	B-V	U-B	V-R	V-I
44 028	0.002	-0.012	-0.018	0.001	0.002
44 113	0.006	0.000	-0.031	0.004	-0.005
76 280	0.001	0.009	0.013	-0.006	-0.015
76 281	-0.007	0.018	-0.056	0.002	-0.010
93 103	0.003	0.018	0.025	-0.003	-0.001
95 016	-0.007	-0.019	--	0.006	0.010
95 096	-0.019	0.008	-0.027	0.006	0.018
96 405	0.002	0.013	-0.001	0.001	0.007
96 406	-0.004	-0.007	-0.023	0.000	0.005
98 185	0.007	-0.016	-0.006	0.006	0.009
98 193	-0.006	-0.009	0.007	-0.003	-0.001
98 650	0.006	0.000	0.011	-0.004	0.009
98 653	-0.005	0.028	-0.022	-0.010	-0.002
98 667	0.004	0.013	-0.001	0.012	0.021
98 670	0.000	-0.005	0.022	-0.001	-0.004
98 671	0.000	-0.005	0.081	0.001	-0.005
98 682	-0.002	0.021	0.006	-0.005	-0.021
98 685	-0.009	0.025	-0.047	-0.007	-0.004
99 438	-0.005	-0.009	0.074	0.001	0.007
99 447	-0.020	0.011	0.007	-0.005	0.011
100 267	0.007	0.006	-0.016	0.004	0.095
100 269	0.016	-0.007	0.005	0.008	0.079
113 274	-0.007	0.004	0.009	-0.006	-0.008
113 276	-0.009	0.006	0.008	0.004	-0.008
114 750	0.013	-0.020	0.043	-0.001	-0.040
GD 71	0.003	0.006	0.024	0.003	-0.012

Figure 12: Identification chart of field #5 around Landolt star GD 71 (labelled "A"). Only stars brighter than V=17.5 mag are labelled. Labels are placed right from the stars, except for #19, #126 and #181 that are placed left, #28, #53, #90, #94, #262, #274 and #291 placed down and #52, #113, #161 and #305 placed up

Equatorial coordinates were computed for all selected stars using the USNO-A V2.0 catalogue (Monet et al. 1998) as reference. In each field, several stars were cross-identified with the USNO catalogue by ocular inspection. These stars were used to compute initial linear transformation equations from frame coordinates (x,y) to $(\alpha,\delta)$, including scale and rotation terms. The resulting equatorial coordinates were introduced into an iterative crossing-fitting procedure until convergence in the number of matched stars was reached. We did not restrict this process to the selected sample; instead, all stars detected in our CCD data were used. The final rms residual of the fittings were in both coordinates around 0.32 arcsec, in accordance with the precision claimed for USNO-A V2.0 (around 0.25 arcsec in each coordinate) and with the deviations that may arise from proper motions due to epoch differences.

Figure 13: Identification chart of field #6 around Landolt stars SA 98 185 (labelled "A") and SA 98 193 (labelled "B"). Labels are placed right from the stars, except for #36, #51, #64, #110, #129 and #130, all of them placed down, and SA 98 193 (B), #17, #24, #54, #84, #102, all of them placed up

Figure 14: Identification chart of field #7 around Landolt stars SA 98 650 (labelled "A"), SA 98 653 (labelled "B"), SA 98 667 (labelled "C"), SA 98 670 (labelled "D"), SA 98 671 (labelled "E"), SA 98 682 (labelled "F"), SA 98 685 (labelled "G") and SA 98 676 (labelled "H"). Labels are placed right from the stars, except for #21 and #45, placed up, and SA 98 650 (A) and #63, placed down

Figure 15: Identification chart of field #8 around Landolt stars SA 99 438 (labelled "A") and SA 99 447 (labelled "B"). Labels are placed right from the stars, except for #24 and #35, placed up

Figure 16: Identification chart of field #9 around Landolt stars SA 76 280 (labelled "A") and SA 76 281 (labelled "B"). Labels are placed right from the stars, except for #24, #38 and #39, placed up, and for #26 and #31, placed left

Several discordant matches with USNO-A V2.0 (further than 1 arcsec) were due to relatively high proper-motion stars. Other discordant matches were in every case related to double stars not resolved in USNO plate scans, but well-separated in our CCD data. In these cases, the match was assigned to the primary (brighter) component.

The positions given for our stars were determined by applying the transformation equations from (x,y) to $(\alpha,\delta)$(J2000.0 equinox, at the mean epoch of the observations). These equatorial coordinates were used to match our stars with AC 2000 catalogue (Urban et al. 2000). Due to the brighter limiting magnitude of AC 2000, few of our stars have a cross-identification with this catalogue.