Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.
Here are five fields you may use to check the color terms of your telescope and camera. It is best to observe more than a single field on the same night, and to repeat each field at least five or six times.
The first four fields come from Landolt, A. U. 1992, AJ, 104, 340; the M67 "dipper asterism" is based on data from Alain Porter [who merged photometry from a number of sources: Gilliland et al. (1991), Smith and Janes (1984), Joner and Taylor (1990), Schild (1983), and references therein]. All photometry is on the Johnson-Cousins system. In the four Landolt fields, the star marked "X" is the named PG star.
Gilliland, R. L., Duncan, D. K., Brown, T. M., Suntzeff, N. B., and Lockwood, G. W. 1991, AJ 101, 541. Landolt, A. U. 1992, AJ, 104, 340 Joner, M. D. and Taylor, B. J. 1990, PASP 102, 1004. Schild, R. E. 1983, PASP, 95, 1021. Smith, G. H. and Janes, K. A. 1984, AJ, 89, 487.
Field: PG 0231+051 RA 02:33:41 Dec +05:18:40 (2000) Star V B-V U-B V-R R-I ---------------------------------------------------------------- PG 0231+051 16.105 -0.329 -1.192 -0.162 -0.371 A 12.772 0.710 0.270 0.405 0.394 B 14.735 1.448 1.342 0.954 0.998 C 13.702 0.671 0.114 0.399 0.385 D 14.027 1.088 1.046 0.675 0.586 E 13.804 0.677 0.201 0.390 0.369
Field: PG 0918+029 RA 09:21:28 Dec +02:46:03 (2000) Star V B-V U-B V-R R-I ---------------------------------------------------------------- PG 0918+029 13.327 -0.271 -1.081 -0.129 -0.159 A 14.490 0.536 -0.032 0.325 0.336 B 13.963 0.765 0.366 0.417 0.370 C 13.537 0.631 0.087 0.367 0.357 D 12.272 1.044 0.821 0.575 0.535
Field: PG 1633+099 RA 16:35:24 Dec +09:47:50 (2000) Star V B-V U-B V-R R-I ---------------------------------------------------------------- PG 1633+099 14.397 -0.192 -0.974 -0.093 -0.116 A 15.256 0.873 0.320 0.505 0.511 B 12.969 1.081 1.007 0.590 0.502 C 13.229 1.134 1.138 0.618 0.523 D 13.691 0.535 -0.025 0.324 0.327
Field: PG 2213-006 RA 22:16:28 Dec -00:21:15 (2000) Star V B-V U-B V-R R-I ---------------------------------------------------------------- PG 2213-006 14.124 -0.217 -1.125 -0.092 -0.110 A 14.178 0.673 0.100 0.406 0.403 B 12.706 0.749 0.297 0.427 0.402 C 15.109 0.721 0.177 0.426 0.404
The "dipper asterism" in M67 is a compact groups of stars. Here's a picture at the same scale as all the others -- about 15 arcminutes on a side:
And here's a closeup of the region with the stars of interest:
Field: M67 dipper asterism RA 08:51:21 Dec +11:46:16 (2000) Star V B-V U-B V-R R-I ---------------------------------------------------------------- 81 10.024 -0.080 -0.388 -0.040 -0.028 106 13.095 0.562 0.060 0.338 0.332 108 9.711 1.370 1.539 0.707 0.644 111 12.730 0.560 0.051 0.319 0.318 117 12.625 0.784 0.278 0.466 0.438 124 12.119 0.457 0.043 0.280 0.278 127 12.776 0.552 0.064 0.322 0.328 128 13.162 0.569 0.045 0.338 0.310 129 13.189 0.574 0.075 0.341 0.348 130 12.894 0.448 0.029 0.283 0.292 134 12.262 0.580 0.065 0.334 0.325 135 11.445 1.060 0.913 0.556 0.499
Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.