  Low radio frequencies are favourable for the identification of emission from
non-thermal processes such as synchrotron emission. The massive protostellar
jet associated with IRAS 18162-2048 (also known as the HH80-81 system) has been
imaged at low radio frequencies: 325, 610 and 1300 MHz, using the Giant
Metrewave Radio Telescope, India. This is the first instance of detection of
non-thermal emission from a massive protostellar jet at such low radio
frequencies. The central region displays an elongated structure characteristic
of the jet. In addition, the associated Herbig-Haro objects such as HH80, HH81,
HH80N, and other condensations along the inner regions of the jet exhibit
negative spectral indices. The spectral indices of most condensations are
~-0.7, higher than the value of -0.3 determined earlier using high frequency
measurements. The magnetic field values derived using radio flux densities in
the present work, under the assumption of equipartition near minimum energy
condition, lie in the range 116-180 microgauss. We probe into the hard X-ray
nature of a source that has been attributed to HH80, in an attempt to reconcile
the non-thermal characteristics of radio and X-ray measurements. The flux
densities of condensations at 610 MHz, measured nearly 11 yrs apart, display
variability that could be ascribed to the cooling of condensations, and
emphasize the importance of coeval or nearly-coeval measurements for estimation
of spectral indices.
