Observations of pulsars at 7 millimeters

We report the first observations of a selected sample of pulsars at 43 GHz (7 mm). All four pulsars (B0329+54, B0355+54, B1929+10, and B2021+51) were successfully detected with pulse shapes and widths similar to those at lower frequencies. For B0329+54, we see the well-known profile mode changing behavior observed at low frequencies. The triple-frequency receiver system used for the observations allowed a spectral study spanning almost 30 GHz, using bands centered at 15, 23, and 43 GHz. Our results strengthen the claim for unusual spectral behavior of pulsars, i.e., a flattening (or possible upturn) of the pulsar spectrum at millimeter wavelengths.