  We present solution of the problem of wavelength calibration for Hamilton
Echelle spectrograph using hollow cathode lamp, which was operated at Lick
Observatory Shane telescope before June 9, 2011. The spectrum of the lamp
claimed to be thorium-argon, contains, in addition to the lines of thorium and
argon, a number of the unrecognized lines identified by us with tantalum. Using
atomic data for measured lines of tantalum and thorium, we estimated the
temperature of the gas in the lamp as T=3120+/-60 K. From the atomic line
database VALD3 we selected all lines of TaI and TaII which can be seen in the
spectrum of the lamp and compiled a list for the use in the processing of
spectral observations. We note a limitation of the accuracy of calibration due
to the influence of the hyperfine line splitting.
