  We present 8.5 arcsec resolution 1.1mm continuum imaging and CO spectroscopic
redshift measurements of eight extremely bright submillimetre galaxies
identified from the Planck and Herschel surveys, taken with the Large
Millimeter Telescope's AzTEC and Redshift Search Receiver instruments. We
compiled a candidate list of high redshift galaxies by cross-correlating the
Planck Surveyor mission's highest frequency channel (857 GHz, FWHM = 4.5
arcmin) with the archival Herschel Spectral and Photometric Imaging Receiver
(SPIRE) imaging data, and requiring the presence of a unique, single Herschel
counterpart within the 150 arcsec search radius of the Planck source positions
with 350 micron flux density larger than 100 mJy, excluding known blazars and
foreground galaxies. All eight candidate objects observed are detected in 1.1mm
continuum by AzTEC bolometer camera, and at least one CO line is detected in
all cases with a spectroscopic redshift between 1.3 < z(CO) < 3.3. Their
infrared spectral energy distributions mapped using the Herschel and AzTEC
photometry are consistent with cold dust emission with characteristic
temperature between $T_d$ = 43 K and 84 K. With apparent infrared luminosity of
up to L(IR) = $3\times10^{14} \mu^{-1} L_\odot$, they are some of the most
luminous galaxies ever found (with yet unknown gravitational magnification
factor $\mu$). The analysis of their spectral energy distributions (SEDs)
suggests that star formation is powering the bulk of their extremely large IR
luminosities. Derived molecular gas masses of $M_{H2}=(0.6-7.8)\times 10^{11}
M_\odot$ (for $\mu$~10) also make them some of the most gas-rich high redshift
galaxies ever detected.
