though the deviation from the general shape of the sequence is very slight (see below for further comments).

$8500$ K $\leq~T_{\rm eff}~\leq~35000$ K (A4V - O8V)

($u-v$) $\in~[-1.70;0.20]$\
$U-V =  0.008 + 0.843 (u-v) \pm 8.10^{-3}$

The general shape of our synthetic main sequence is pretty close to a straight line in the ($U-V$) vs ($u-v$) diagram, so that, if precision is not critical (at most 0.1 mag), one can also use the following relation:

$4000$ K $\leq~T_{\rm eff}~\leq~35000$ K (K7V - O8V)

($u-v$) $\in~[-1.70;2.80]$\
$U-V =  0.100 + 0.930 (u-v) \pm 5.7\,10^{-2}$

### ($U-V$) vs ($uvw1-v$)

$4000$ K $\leq~T_{\rm eff}~\leq~7000$ K (K7V - F1V)

($uvw1-v$) $\in~[0.65;4.50]$\
$U-V =  -0.201 + 0.786 (uvw1-v) - 0.029 (uvw1-v)^2 \pm 1.9\,10^{-2}$

$7000$ K $\leq~T_{\rm eff}~\leq~7750$ K (F1V - A7V)

($uvw1-v$) $\in~[0.50;0.65]$\
No possible transformation. The problem is however very slight and seems to be due to the Kurucz synthetic spectra rather than to the filters. The best here is to use the general relation proposed below for the whole temperature range.

$7750$ K $\leq~T_{\rm eff}~\leq~35000$ K (A7V - O8V)

($uvw1-v$) $\in~[-2.45;0.50]$\
$U-V =  0.004 + 0.577 (uvw1-v) \pm 9.10^{-3}$

The same kind of considerations as for the ($U-V$) vs\
($u-v$) case holds concerning 