The LOFAR Two Meter Sky Survey LoTSS DR2
(:bibcode:`2022A&A...659A...1S`) obtained radio data from 27% of the
northern sky between 120 and 168 MHz in the year 2014 through 2020. This
service publishes polarization spectra of extragalactic radio sources
(radio galaxies and blazars) and the rotation measures derived from them.
We also give redshifts for all sources. The data has a spatial resolution
of 20 arcsec.
The catalog 1WHSP is the result of a multi-frequency selection for
blazars like SED, further filtered using IR-radio and IR-X-ray
flux-ratios. The sample assembled contains almost 992 sources of HSP
blazars, of which 425 are previously known blazars, 151 new
identifications and 416 blazar candidates. On the very high energy
trend, 299 are confirmed GeV gamma-ray photons emitters and 36 have
already been detected in the TeV band.
