The ASTE (Atacama Submillimeter Telescope Experiment) is a 10-m submillimeter telescope located near the ALMA (Atacama Large Millimeter/submillimeter Array) site in Chile. Recently, the ASTE heterodyne receiver system has been upgraded with a new cryostat and two sub-mm-wave heterodyne receivers. The cryostat has three receiver ports. Its cooling capacity is improved with new design compared to a previous three-cartridge cryostat. The two new receivers are dual polarization Superconductor-Insulator-Superconductor (SIS) sideband-separating receivers in 345 GHz and 460 GHz bands. The 345 GHz band receiver has 55 GHz bandwidth. The single-sideband noise temperature TSSB measured in the laboratory is between 62 K and 440 K. The 460 GHz band receiver was originally an engineering qualification model of the ALMA Band 8 cartridge. The design of SIS mixer devices has been optimized for full coverage of ALMA Band 8 frequency (385-500 GHz). TSSB of the receiver is between 98 K and 257 K. The receiver system was installed on ASTE in March 2017. We have started to provide it for open-use observations after our CSV (Commissioning and Science Verification) activities.
Two large correlators have been constructed to combine the signals captured by the ALMA antennas deployed on the
Atacama Desert in Chile at an elevation of 5050 meters. The Baseline correlator was fabricated by a NRAO/European
team to process up to 64 antennas for 16 GHz bandwidth in two polarizations and another correlator, the Atacama
Compact Array (ACA) correlator, was fabricated by a Japanese team to process up to 16 antennas. Both correlators meet
the same specifications except for the number of processed antennas. The main architectural differences between these
two large machines will be underlined. Selected features of the Baseline and ACA correlators as well as the main
technical challenges met by the designers will be briefly discussed. The Baseline correlator is the largest correlator ever
built for radio astronomy. Its digital hybrid architecture provides a wide variety of observing modes including the ability
to divide each input baseband into 32 frequency-mobile sub-bands for high spectral resolution and to be operated as a
conventional 'lag' correlator for high time resolution. The various observing modes offered by the ALMA correlators to
the science community for 'Early Science' are presented, as well as future observing modes. Coherently phasing the
array to provide VLBI maps of extremely compact sources is another feature of the ALMA correlators. Finally, the status
and availability of these large machines will be presented.