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Well, that is what I generally work with: tables. I had the paper but I thought it was meant only to Tycho-1. So, we use it and get for the same examples: eps Lup 3.37 -0.18 / 3.355 -0.165 Henden= 3.37 -0.18 / 3.364 -0.154 Bessell= 3.37 -0.18 / 3.366 -0.175 ups And 4.09 0.54 / 4.099 0.496 Henden= 4.09 0.54 / 4.102 0.501 Bessell= 4.09 0.54 / 4.090 0.535 iot Lup 3.55 -0.18 / 3.517 -0.165 Henden= 3.55 -0.18 / 3.527 -0.153 Bessell= 3.55 -0.18 / 3.546 -0.174 gam Tuc 3.99 0.40 / 3.994 0.362 Henden= 3.99 0.40 / 3.999 0.368 Bessell= 3.99 0.40 / 3.986 0.398 So, this is the table we should use. Thanks Brian again ;-)) Sebastian. ----- Original Message ----- From: "Brian Skiff" <Brian.Skiff@lowell.edu> To: <aavso-discussion@informer2.cis.mcmaster.ca>; <aavso-seq@yahoogroups.com>; <vsnet-chat@ooruri.kusastro.kyoto-u.ac.jp> Sent: Sunday, May 25, 2003 5:30 PM Subject: [vsnet-chat 6420] Tycho to standard V > Since it appears the (probable) "best" transformation of the Tycho > photometry to Johnson V and B-V needs to be sent around again, here is > Bessell's look-up table, followed by a very useful polynomial for the > VT-to-V conversion from Mike Linnolt. > Briefly, Bessell used the E-region primary standards data for his > analysis, showing that the standard Tycho-consortium transformation is > not very good and is easy to improve. He published only a look-up table, > and not an analytical function, but Linnolt has recovered this at least for > getting V. The linear consortium transformation is the source of the > systematic errors that Sebastian has noticed. > > \Brian > > ============================================================================ === > > Corrections to put Hipparcos/Tycho data on the standard V and B system > > from: 2000PASP..112..961B > BESSELL M.S. > Publ. Astron. Soc. Pac., 112, 961-965 (2000) [July 2000 issue] > The Hipparcos and Tycho photometric system passbands. > > > > TABLE 2 > RELATION BETWEEN BT-VT AND HIPPARCOS/TYCHO DATA FOR B-G > MAIN-SEQUENCE STARS AND K-M GIANTS > > BT-VT V-VT del(B-V) V-HP > > -0.250... 0.038 0.031 0.066 > -0.200... 0.030 0.021 0.051 > -0.150... 0.022 0.011 0.036 > -0.100... 0.015 0.005 0.021 > -0.050... 0.008 0.002 0.006 > -0.000... 0.001 -0.005 -0.011 > 0.050... -0.005 -0.010 -0.025 > 0.100... -0.012 -0.017 -0.038 > 0.150... -0.018 -0.020 -0.048 > 0.200... -0.024 -0.021 -0.058 > 0.250... -0.029 -0.023 -0.069 > 0.300... -0.035 -0.025 -0.079 > 0.350... -0.040 -0.025 -0.087 > 0.400... -0.045 -0.026 -0.094 > 0.450... -0.050 -0.030 -0.101 > 0.500... -0.054 -0.035 -0.108 > 0.550... -0.059 -0.045 -0.114 > 0.600... -0.064 -0.051 -0.120 > 0.650... -0.068 -0.060 -0.127 > 0.700... -0.072 -0.068 -0.131 > 0.750... -0.077 -0.076 -0.134 > 0.800... -0.081 -0.085 -0.137 > 0.850... -0.085 -0.094 -0.142 > 0.900... -0.089 -0.104 -0.147 > 0.950... -0.093 -0.113 -0.151 > 1.000... -0.098 -0.122 -0.155 > 1.050... -0.102 -0.131 -0.158 > 1.100... -0.106 -0.142 -0.157 > 1.150... -0.110 -0.154 -0.160 > 1.200... -0.115 -0.166 -0.162 > 1.250... -0.119 -0.178 -0.164 > 1.300... -0.124 -0.189 -0.166 > 1.350... -0.128 -0.199 -0.166 > 1.400... -0.133 -0.210 -0.165 > 1.450... -0.138 -0.222 -0.164 > 1.500... -0.143 -0.234 -0.161 > 1.550... -0.148 -0.245 -0.157 > 1.600... -0.154 -0.256 -0.153 > 1.650... -0.160 -0.266 -0.148 > 1.700... -0.165 -0.277 -0.143 > 1.750... -0.172 -0.288 -0.137 > 1.800... -0.178 -0.299 -0.131 > 1.850... -0.185 -0.309 -0.125 > 1.900... -0.191 -0.320 -0.119 > 1.950... -0.199 -0.331 -0.112 > 2.000... -0.206 -0.342 -0.106 > > -------------------------------------------------------------------------- ----- > > Date: Fri, 10 Jan 2003 13:16:03 -1000 (HST) > From: Michael Linnolt <linnolt@hawaii.edu> > Subject: Re: Bessell lookup table > To: Brian Skiff <Brian.Skiff@lowell.edu> > > Brian, > > While working on loading the Bessel data table into my charting program, > I noticed that the (V-Vt) vs. (Bt-Vt) is almost perfectly fit by a single > cubic polynomial! > > V-Vt = -0.02(Bt-Vt)^3 + 0.0549(Bt-Vt)^2 - 0.1334(Bt-Vt) + 0.001 > > R^2 = 0.99998 > > Unfortunately the del(B-V) vs. (Bt-Vt) cannot be fit so perfectly by a > polynomial, but a 5th order is within R^2=0.99965 with significant > departures around (Bt-Vt)~0.4 and (Bt-Vt)~0.15. > > Clear skies, > Mike Linnolt >
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