Commissioning of N¯ amakanui on the JCMT Izumi Mizuno a , Per Friberg a , Ryan Berthold a , Harriet Parsons a , Chih-Chiang Han b , Alexis Acohido a , Graham Bell a , David Berry a , Dan Bintley a , Ming-Tang Chen b , Alyssa Clark a , Jamie Cookson a , Vernon Demattos a , Jessica Dempsey a , Jason Fleck a , Kuo-chieh Fu b , Miriam Fuchs a , Sarah Graves a , Paul Ho a , Sung-Po Hsu b , YauDe Huang b , Xue-Jian Jiang a , Derek Kubo b , John Kuroda a , Shaoliang Li a , Steve Mairs a , Callie Matulonis a , Mailani Neal a, d , Neal Oliveira a , Maren Purves a , Mark Rawlings a , Ya-Che Shih b , Kevin Silva a , Ed Sison a , Patrice Smith a , Ranjani Srinivasan b , William Stahm a , Alexandra J. Tetarenko a , Pablo Torne a, c , Craig Walther a , Chao-Ching Wang b , Ta-Shun Wei b a East Asian Observatory, 660 N. A’oh¯ ok¯ u Place, HI, USA 96720; b Academia Sinica, Institute of Astronomy & Astrophysics P.O. Box 23-141, Taipei, Taiwan; c Instituto de Radioastronom´ ıa Milim´ etrica (IRAM), Avda. Divina Pastora 7, Local 20, 18012 Granada, Spain; d New Mexico Institute of Mining and Technology, 801 Leroy Pl, Socorro, NM 87801, USA ABSTRACT N¯amakanui is an instrument containing three inserts in an ALMA type Dewar. The three inserts are ‘Ala‘ihi , ‘ ¯ U‘¯ u and ‘ ¯ Aweoweo operating around 86, 230 and 345GHz. The receiver is being commissioned on the JCMT. It will be used for both Single dish and VLBI observations. We will present commissioning results and the system. Keywords: Instrument, Heterodyne, JCMT, submillimeter, Single-dish observation, VLBI 1. INTRODUCTION The JCMT is the largest single dish telescope dedicated to sub-millimeter observing in the world. It has a 15-m primary dish and is often recognized by its iconic GoreTex membrane that enables it to observe in higher wind-speeds than would otherwise be possible. Located at 14,000’ on Maunakea in Hawai‘i, the high altitude combined with typically stable inversion layer trapping moisture at lower elevations, enables the JCMT to observe in some of the best sub-millimeter observing conditions in the Northern Hemisphere. The JCMT has a suite of instruments that enable the observatory to execute continuum observing (SCUBA-2 at 450 and 850 μm 1 ), linear continuum polarization (POL-2, ancillary to SCUBA-2 for use at both 450 and 850 850 μm 2 ), and heterodyne observations (HARP, 3 operating between 325 to 375 GHz). The JCMT is now also home to the new N¯ amakanui receiver, that will be used both for single dish observations and also for VLBI observations such as the Event Horizon Telescope (EHT) and with the East Asia VLBI Network. 4 In this paper we discuss the details of the N¯amakanui receiver and its three inserts: ‘Ala‘ihi , ‘ ¯ U‘¯ u and ‘ ¯ Aweoweo . Software to operate and monitor N¯ amakanui has been developed and we present the performance of N¯amakanui and commissioning results from ‘ ¯ U‘¯ u . Currently ‘ ¯ U‘¯ u is available to the community for shared risk science observations, and we present some recent science observation taken with ‘ ¯ U‘¯ u. 2. OVERVIEW OF N ¯ AMAKANUI The N¯ amakanui instrument is a spare receiver for the Greenland Telescope (GLT), 5, 6 on loan to the East Asian Observatory for use on the JCMT courtesy of ASIAA. The N¯ amakanui contains three inserts: ‘Ala‘ihi , ‘ ¯ U‘¯ u and ‘ ¯ Aweoweo operating around 86, 230 and 345GHz. One of the insert of ‘Ala‘ihi is a new frequency range for JCMT, operating around 86 GHz. The ‘ ¯ U‘¯ u insert replaced the JCMT’s RxA3 single polarization dual side-band receiver that was retired in June 2018 and operated between 212 and 274 GHz. ‘ ¯ U‘¯ u will cover most of the RXA3 operation frequency range, but with higher sensitivity by receiving dual polarizations. The ‘ ¯ Aweoweo insert has an operational sky frequency range that overlaps much arXiv:2012.07349v1 [astro-ph.IM] 14 Dec 2020