  The rotational spectra of DCO+ and its two isotopomers D{13}^CO+ and
DC{18}^O+, produced in a negative glow discharge cell, have been recorded in
the 137-792 GHz region, which includes lines from J=2-1 up to J=11-10. The
determined rotational and centrifugal distortion constants allow to predict the
DCO+ rotational spectrum up to 1000 GHz with an accuracy of 1 part in 10^8 or
better. This is important for kinematic studies of dense molecular cloud cores
and for future far-infrared observations. We also report on the first detection
of the hyperfine structure of the DCO+(1-0) line made at the IRAM 30m antenna,
toward the quiescent starless cloud core L1512, in the Taurus Molecular Cloud.
We point out that this is the first observation of the hyperfine splitting due
to the deuteron. This allowed us to quantify the effects of the hyperfine
splitting on the line width determination; if the hyperfine structure is not
taken into account in the line fit, the DCO+(1-0) line width is overestimated
by a significant factor (> 2).
