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Aloha Kākou: Observatory Update and Science News • March 2021

Figure 1: From left to right. The shadow of Maunakea, the volcano Hualālai, Pu'u Poliʻahu, the Caltech Submillimeter Observatory (CSO), and the James Clerk Maxwell Telescope. Image Credit: Tom Kerr

Director's Corner  It is my pleasure to warmly welcome you with aloha to the first of  EAO/JCMT’s Quarterly "Aloha Kākou: Observatory Update and Science News" publication. Since the last JCMT Newsletter I am pleased to report we had a record number of proposals to our observatory for the 21B semester, most notable was our over-subscription factors. JCMT Users have applied for a factor of 3.4 more hours than are available in the 21B queue which runs from the start of August through to the end of January. The start of March saw some particularly poor weather on Maunakea with JCMT closed on 9 nights due to snow, fog, and icy conditions. Thankfully our hard-working team of telescope operators have ensured that we have been able to push on with science making the most of the more recent dry observing conditions. It is always our mission to get great data to our community.  Also, many thanks to our user's community for maintaining the high proposal pressure especially as the 21B call was very close to the extended 21A call.  We are very happy to continue to deliver great science and great capabilities for our users.

JCMT staff have made great strides to better describe and quantity the Flux Calibration Factors for use with SCUBA-2 data - keep an eye out for more details this summer - and be sure to keep up-to date by visiting the relevant SCUBA-2 calibration pages on our website.

Nāmakanui commissioning efforts continue. Suffice to say we are pleased to have a stable configuration of the 230GHz insert, `Ū`ū and are starting to make progress with our 345GHz insert, `Āweoweo. In January the JCMT had a successful Dress Rehearsal for the upcoming Event Horizon Telescope observations. This was despite deteriorating winter weather conditions on both Maunakea in Hawaiʻi and on Kitt Peak Arizona. The success of the Dress Rehearsal using Nāmakanui was another step in the process to ensure the JCMT will be ready to participate in this April’s Event Horizon Telescope observing run.

To our EAO community and friends I hope you are having a prosperous start to the new year, I hope you are all safe and well and wish you clear skies.

-Paul Ho

Figure 2: The dusty material of the hub (black and white) overlaid with outlines of the spokes (multiple colors) and lines symbolizing the direction of the magnetic fields in this area of space (yellow and white). C1-C6 label dense regions within and next to the main hub.

Science News - Jia-Wei Wang, ASIAA (Edited by Steve Mairs, EAO)

Every year about 3 stars are born in our Milky Way Galaxy. They are formed from dusty, gaseous material that collects in the space between the stars. The James Clerk Maxwell Telescope (JCMT) is specially designed to study this star-forming material and over the past 30 years, the observatory has played a major role in developing our understanding of how our own Sun and planets first came to be. Previous observations have found that stars commonly form in clusters rather than individually. These forming clusters seem to gather in central "hubs" of dusty material that are connected to long, tendril-like structures like the spokes of a wagon wheel. Understanding how these large-scale structures form is of great interest to astronomers because these are the regions that represent the very earliest stages of star formation and they give deep insights into the beginning of this million-year-long process.

A new study led by Dr. Jia-Wei Wang of the Academia Sinica Institute of Astronomy and Astrophysics has used the JCMT to observe one of these "hub/spoke" systems of star-forming material in order to perform careful measurements of the different forces at play. There is a constant struggle between the force of gravity that works to pull material together to form stars and other forces that work to separate the material such as the pressure created from an increase in temperature (like the liquid in a thermometer expanding as it gets hotter) and turbulent motions (like the wake behind a boat). If gravity wins, a star forms. If the other forces win, no star forms. In addition, our galaxy is filled with magnetic fields (the same kind that allow your fridge magnets to stick) that also play a role that is not fully understood. Using data from another telescope called "IRAM" (which resides in Spain), the team was able to study the spokes connected to the central hub and determine the direction in which the material is physically flowing (see Figure 2).

The team found that the force of gravity overpowers the forces associated with the magnetic field or gas motion by a significant amount, meaning this system is well on its way to collapsing and forming more stars. By thoroughly investigating the surrounding environment, the authors were able to establish that diffuse material in the outskirts of the image will be dragged onto the main spokes, where it will then be funneled towards the central hub (see Figure 3). Even the magnetic fields seem to bend in the direction of the gas and dust flowing down the spokes which, themselves, remain as stable structures that do not break apart over long periods of time.

This study highlights the organized, but complex nature of the birth of stars. For more detailed information, click here.

Figure 3: Schematic diagram of the hub/spoke system

Figure 4: Photo of the ʻŪʻū Warm Cartridge Assembly. Top: instrument configuration with the IF Low Noise Amplifier bypassed on NU1L. Bottom: instrument configuration after the replacement of the IF Low Noise Amplifier.

Observatory Update - Dr. Harriet Parsons, Head of Operations, EAO

They say you are only as old as you feel, but a telescope really is only as old as its latest instrument! Right now JCMT staff are commissioning Nāmakanui, the JCMT’s latest instrument that was installed at the telescope in September 2019. Nāmakanui was built by a team at ASIAA (Taiwan) and is on loan to the JCMT as a spare receiver for the Greenland Telescope. Nāmakanui will enable our community to observe the complex chemistry of the Universe at wavelengths around 3.5mm, 1.3mm, and 0.9mm (86GHz, 230GHz, and 345GHz) using the instrument’s three inserts: ʻAlaʻihi, ʻŪʻū, and ʻĀweoweo. For the past year, staff focus has been on the 230GHz insert ʻŪʻū.

Commissioning of ʻŪʻū is nearing completion. The instrument is finally in a stable hardware state after mixer replacements, cable work and then in early March the replacement of a Low Noise Amplifier (LNA) in the Warm Cartridge Assembly, see Figure 4. In addition to the hardware, several software bugs discovered during the commissioning processes have been resolved and the overall efficiency in terms of data storage has been improved for both ʻŪʻū/Nāmakanui data (blank data now not recorded) as well as for HARP data. Staff are also working on code for the calculation of the ʻŪʻū Main Beam Efficiency that will be critical for users.

The final focus now for the ʻŪʻū system is on the backend, ACSIS. For a number of months, artificial p-cygni-like features were causing issues in the baseline of some data. This issue has been resolved by staff meticulously testing and, where necessary, replacing cables and connections within ACSIS. Additionally, an issue with some low-level spurious lines has been determined to be related to how far Nāmakanui is pushing the limits of ACSIS - specifically a filter on one of the LO stages (LO2). In order to adapt to how much ʻŪʻū and ʻĀweoweo are pushing ACSIS due to their larger IF ranges a new filter has been ordered and once installed it is expected that the spurious line issue will be resolved.

With the effort to commission ʻŪʻū coming to a close, observatory staff will shift focus to the 345GHz insert ʻĀweoweo. Already observatory staff have finalized the pointing model for this insert and are taking the first step in the commissioning process of observing standard sources as a way to check system performance. It is likely that the observatory will offer Shared Risk Observing with ʻĀweoweo during the 22A call for proposals.

ʻĀweoweo will be a fantastic tool for the EAO community - particularly for those interested in understanding the chemistry of compact sources. To a sensitivity of 0.01K in CO (3-2) ʻĀweoweo will be a factor of ~2.5 times faster than HARP towards a single point source. ʻĀweoweo will also when fully commissioned, have a wider frequency coverage than HARP (276 – 371GHz, compared to 325 - 375 GHz). HARP, with its 16 receptors, will remain more effective for covering large fields of view but we encourage our community to see how ʻĀweoweo can be used to maximize their science. Although the aim is to open the first ʻĀweoweo call for 22A this new Nāmakanui 345GHz insert might be available earlier, so be sure to keep an eye out for its advertisement during inter-semester calls as it may be available to users through the Rapid Turnaround and/or Urgent queue Call.

Both ʻŪʻū and ʻĀweoweo are expected to be used during the upcoming 2021 Event Horizon Telescope (EHT) campaign. Staff are excited to use these instruments during this ambitious global endeavor to understand the Black Holes at the center of M87 and at the center of our Milky Way Galaxy. Notable work from staff in preparation for this campaign has included the installation of a UPS unit in the Plinth area to support the EHT’s MARK6 recorders and the addition of new remote monitoring systems to remove the pressure for staff to be at the summit during EHT observing. Science support and monitoring of systems will be done remotely this year both from the EAO offices in Hilo and from our staff’s remote workspaces at home. The campaign is expected to take place in mid-April.

This copy of "Aloha Kākou: Observatory Update and Science News" was produced and edited by Callie Matulonis, Steve Mairs, and Harriet Parsons.

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