# Brian Skiff wrote on vsnet-chat (msg 5427), 30 July 2002 # # The list below contains reliable red standards that might be suitable for # observation of Miras and carbon stars with photoelectric/CCD instruments--- # and more generally for seeing how one's system behaves in this regime. These # are well observed on the Johnson-Cousins UBVRI system # and have reasonably small # uncertainties, suggesting they are not greatly variable. # Most of the stars are selected from the various Landolt standards papers, # and for the most part are fainter than V mag. 7 and redder than B-V = 1.75, # or V-R = 1.0. Although there are additional Landolt red stars, none are # well-observed, and the errors on the figures makes them unsuitable as # standards. None of the Cousins E-region standards is quite as red as these. # Additional _provisional_ southern red standards have been published by # Koen et al. (2002MNRAS.334...20K). I show here some well-observed stars with # small scatter in the measurements, indicating relative lack of variability. # Arne Henden noted that since the stars are bright toward the red, one # might end up using the fainter stars here when observing in VRI colors, but # using the brighter stars when doing U-B in order to get enough signal. # Because of the slight variability, another suggestion is to observe as many of # these stars as possible in hopes of being able to average out the scatter that # will inevitably occur in fitting the data. # Many of the of stars are designated or suspected variables, and are at # least slightly variable in V (0.03-0.05 mag. range). Except for U-B, however, # the _colors_ should be fairly stable. An odd exception is HD 172829 = HK Aql, # which is certainly constant. A comparable star in the northern winter sky is # HD 27482, which is another strongly reddened ordinary K-giant star. # If you can # observe stars as bright as these, I recommend you consider them as very red # "friends". # Few photometric systems are linear in this color regime. If red stars # are on the menu, a suggestion is do two separate solutions: one for stars # with B-V < 1.5, and another for stars with B-V > 1.2 (yes, some overlap) that # will be used to reduce the red stars only. It is likely that one will need # nonlinear terms (usually a cubic) to fit # the very-red regime. Arne Henden also # noted that since the stars are bright toward the red, one might end up using # the fainter stars here when observing in VRI colors, but using the brighter # stars when doing U-B in order to get enough signal. Because of the slight # variability, another suggestion is to observe as many of these stars as # possible in hopes of being able to average # out the scatter that will inevitably # occur in fitting the data. # # # sources # AAH Arne Henden photometry files # C65 Cousins 1965MNSSA..24..120C # K02 Koen et al. 2002MNRAS.334...20K # L67 Landolt 1967AJ.....72.1012L # L83a Landolt 1983AJ.....88..439L # L83b Landolt 1983AJ.....88..853L # L92 Landolt 1992AJ....104..340L # #------------------------------------------------------------------------------- # # Some "very red" standard stars # version: 30 Jul 2002 # # I have modified the format slightly, putting coordinates # in decimal degrees and translating colors into magnitudes. # Values of 99.000 mean "no data available." # -- Michael Richmond, 7/30/2002 # # #Name RA (2000) Dec U B V R I source SA_95-330 58.6292 0.4850 16.402 14.169 12.170 11.004 9.902 L92 GSC 1035.9750 37.0667 99.000 12.980 11.230 10.270 9.350 K02 SA_95-275 58.6833 0.4550 16.973 15.233 13.470 12.459 11.526 L92 HD_27482 65.3125 27.3500 11.840 9.350 7.300 99.000 99.000 L67 SA_97-75 89.4792 -0.1583 15.452 13.352 11.480 10.433 9.481 L92 SA_98-618 102.9583 -0.3550 17.056 14.912 12.720 11.466 10.313 L92 SA_98-675 103.0542 -0.3283 17.235 15.299 13.390 12.308 11.305 L92 HD_57884 110.7792 -4.2133 99.000 11.429 9.130 7.866 6.843 L83a CD-31_4916 115.2625 -31.6833 13.380 11.300 9.140 7.800 6.300 K02 HD_79097 137.9625 -6.9800 11.161 9.228 7.600 6.610 5.513 L83a HD_127300 218.3958 -66.4133 99.000 10.970 9.160 8.090 6.950 K02 CD-52_6295 221.7167 -53.3500 99.000 12.650 10.860 9.850 8.890 K02 HD_140850 236.4917 -1.4450 12.558 10.480 8.810 7.862 6.915 L83a HD_144773 242.4583 -49.6133 12.550 10.340 8.490 7.450 6.430 K02 HD_145968 243.7375 -32.4450 12.100 9.990 8.170 7.130 6.020 K02 BD-14_4395 244.6542 -15.1467 14.750 12.650 10.840 9.580 8.120 L83b HD_160471 265.0500 -2.1517 9.720 7.850 6.180 99.000 99.000 C65 BD+04_3508 266.8875 4.8400 13.150 11.073 9.320 8.346 7.446 L83a HD_315534 275.2167 -23.9433 12.970 11.060 9.300 8.410 7.600 K02 HD_314531 275.7625 -23.5833 13.330 11.180 9.360 8.360 7.360 K02 SA_110-229 280.1917 0.0300 16.941 15.550 13.640 12.442 11.284 L92 HD_172829 280.5750 0.1550 12.734 10.442 8.440 7.254 6.134 L83a SA_110-365 280.7375 0.1233 17.626 15.731 13.470 12.110 10.839 L92 SA_110-280 280.7792 -0.0617 17.274 15.141 12.990 11.755 10.606 L92 SA_110-502 280.7917 0.4617 16.982 14.656 12.330 10.957 9.705 L92 SA_110-446 280.9125 0.3267 99.000 16.840 13.950 11.890 9.880 AAH SA_110-516 280.9167 0.5500 99.000 13.700 11.230 9.760 8.440 AAH SA_110-315 280.9667 0.0133 99.000 15.700 13.630 12.424 11.292 L92 HD_175125 283.6000 -13.0067 12.720 10.870 9.020 7.880 6.590 K02 HD_182665 291.8125 -36.1000 13.080 11.020 9.170 8.030 6.760 K02 SA_111-775 294.3167 0.2017 14.507 12.478 10.740 9.775 8.878 L92 SA_111-1969 294.4292 0.4300 14.645 12.339 10.380 9.203 7.980 L92