Call for proposals for semester 2024B

The East Asian Observatory is happy to invite PI observing proposals for semester 24B at the JCMT. Proposal submission is via the JCMT proposal handling system, Hedwig. For full details, and for proposal submission, please see:

The 24B Call for Proposals closes on the 17th of March, 2024 (2024-03-17 00:00 UT).

If this is your first time using Hedwig, you should ‘Log in’ and generate an account. There is a Hedwig ‘Help’ facility at the upper right corner of each page, and individual Help tags in many other places. Please contact us at if you have remaining questions.

Hours available

The median award of hours to successful program is 14 hours. This ranges to fewer hours in Grades 1-3 due to pressure and weather availability and more in Grade 4/5. Awards range in hours from 1-80 hours in total.

Instrumentation availability

All instrumentation are expected to be available.

24B RA Pressure

Proposers might be interested to note the proposal pressure in terms of RA and DEC. The figure below shows the distribution of target RA proposed in the past under Semester A. When allocating time the TAC is mindful to ensure that time is awarded across a range of RAs.



Proposers should also be mindful of the historical fraction of time in each weather Grade in particular noting the wide variation in ours per weather Grade obtained in any one semester.


The Expanding Partner Program

PIs from Malaysia, Vietnam, Indonesia, India, Brazil and Argentina are welcome to apply for a limited amount of time (<9 hours per program this time constraint is not limited in Grade 5 time) under the “Expanding Partner Program” – a program to encourage astronomers from new JCMT partners to make use of the JCMT.

*** Completion of any science program awarded time is not guaranteed. Approval reliant upon the program being technically feasible, without clashing with existing proprietary data. Data collection is dependent on weather/instrument/queue pressures with adjustments in line with recommendations by the TAC. Under the “Expanding Partner Program” priority will be given to new users of the JCMT.

Stardev Matched Filter Update

On July 1st, 2021 the two-component SCUBA-2 beam profile parameters were updated in accordance with the results published by Mairs et al 2021. This caused a change in the Matched Filter post-processing.

When using a Stardev installation post-July 1st, 2021, executing the matched-filter method is expected to increase the measured peak fluxes of bright point sources by ~15% relative to older versions of Starlink. A similar factor may apply to faint point sources in otherwise “blank fields” but this requires further testing.

See this software blog post for more details!



Pōwehi: New research captures a decade of movement

MAUNAKEA, HAWAIʻI – New analysis of data taken between 2009-2013, some of them not published before, by the James Clerk Maxwell Telescope (JCMT) and the Submillimeter Array (SMA) for the Event Horizon Telescope (EHT) collaboration have revealed the how the black hole Pōwehi is moving over decadal timescales. The analysis reveals the persistence of the crescent-like shadow feature, but also variation of its orientationthe crescent-like shadow appears to be wobbling.  Published today in The Astrophysical Journal, the new result is possible due to scientific advances made by the Maunakea-based telescopes and EHT’s groundbreaking black hole photo in 2019.

The gas falling onto a black hole heats up to billions of degrees, ionizes and becomes turbulent in the presence of magnetic fields. This turbulence is what causes the appearance of black holes to vary over time. Modeling prior data with improved techniques revealed that Pōwehi’s shadow was moving from 2009-2013 and has continued to do so ever since. “The most important thing that we have learned is that the shadow of Pōwehi is always there. That means it is real and is caused by the light bending from the black hole,” said Geoff Bower, Hilo resident and EHT Project Scientist at Academia Sinica Institute of Astronomy and Astrophysics (ASIAA). “The wobble tells us about how gas is flowing around the black hole, varying like clouds in the sky or waves on the ocean. What’s next is to use our improved array and make images over years to come and learn from those changes to answer questions like, ‘How does Pōwehi feed itself?’

Top: Snapshots of the Pōwehi (M87*) black hole obtained through imaging / geometric modeling. The diameter of all rings is similar, but the location of the bright side varies. Bottom: the EHT array of telescopes in 2009-2017. The JCMT and SMA in Hawai`i have continually provided the critical western baseline of the telescope array. Credit: M. Wielgus, D. Pesce & the EHT Collaboration.

Prior experiments were critical to learning more about the famed black hole. Relying on theory, scientists already believed that the shadow was changing over time, but the 2019 image alone provided just a week-long snapshot into its life, too short a time to see those changes or understand them. “This is a little bit like going back to old family photographs and seeing a child’s resemblance to their ancestors,” said Bower. “The more we learn in the future, the more interesting information we can extract from the past. Black holes change on time scales as short as hours and as long as billions of years, so we have a lot to learn.

Very Long Baseline Interferometry (VLBI)—the technique used to power EHT—collects signals from astronomical radio sources, like black holes, at multiple radio telescopes around the world and combines the data to create complete results. “Hawai`i telescopes were crucial to the success of early EHT experiments over the past decade that pioneered the development of VLBI at very short wavelengths,” said Simon Radford, Operations Director of SMA at the Smithsonian Astrophysical Observatory (SAO). “The early experiments required the development and refinement of specialized signal processing electronics, observing techniques, and data analysis methods, setting the stage for the later observations that revealed the image of Pōwehi.

The Maunakea team is already working on preparing for the next EHT observations of Pōwehi in 2021. At JCMT in Hawaii the work is focused on ensuring a new more sensitive instrument Nāmakanui (“Big Eyes”) is ready. This new instrument, Nāmakanui — is funded by ASIAA and named for a type of fish found in and around the islands. “It is rewarding for our Hawai`i staff to see the depth and breadth of new science being mined from a decade of observations,” said Jessica Dempsey, Deputy Director of the East Asian Observatory (EAO) and JCMT. “It’s like we started the sketch ten years ago, and now with new tools and experience, our science teams are going back and able to not just fill in the color in the image, but make that image come to life.

Supplemental information

The James Clerk Maxwell Telescope

With a diameter of 15m (50 feet) the James Clerk Maxwell Telescope (JCMT) is the largest single dish astronomical telescope in the world designed specifically to operate in the submillimetre wavelength region of the electromagnetic spectrum. The JCMT is used to study our Solar System, interstellar and circumstellar dust and gas, evolved stars, and distant galaxies. It is situated in the science reserve of Maunakea, Hawai`i, at an altitude of 4092m (13,425 feet).

The JCMT is operated by the East Asian Observatory on behalf of CAMS (NAOC, PMO, and SHAO); NAOJ; ASIAA; KASI; as well as the National Key R&D Program of China. Additional funding support is provided by the STFC and participating universities in the UK and Canada.

Nāmakanui was constructed and funded by ASIAA, with funding for the mixers provided by ASIAA and at 230GHz by EAO. The Nāmakanui instrument is a backup receiver for the GLT.

The Event Horizon Telescope

The international collaboration of the Event Horizon Telescope announced the first-ever image of a black hole at the heart of the radio galaxy Messier 87 on April 10, 2019 by creating a virtual Earth-sized telescope. Supported by considerable international investment, the EHT links existing telescopes using novel systems — creating a new instrument with the highest angular resolving power that has yet been achieved.

The individual telescopes involved in the EHT collaboration are: the Atacama Large Millimeter/submillimeter Array (ALMA), the Atacama Pathfinder EXplorer (APEX), the Greenland Telescope (since 2018), the IRAM 30-meter Telescope, the IRAM NOEMA Observatory (expected 2021), the Kitt Peak Telescope (expected 2021), the James Clerk Maxwell Telescope (JCMT), the Large Millimeter Telescope (LMT), the Submillimeter Array (SMA), the Submillimeter Telescope (SMT), and the South Pole Telescope (SPT).

The EHT consortium consists of 13 stakeholder institutes; the Academia Sinica Institute of Astronomy and Astrophysics, the University of Arizona, the University of Chicago, the East Asian Observatory, the Harvard-Smithsonian Center for Astrophysics, the Goethe- Universität Frankfurt, the Institut de Radioastronomie Millimétrique, the Large Millimeter Telescope, the Max-Planck-Institut für Radioastronomie, the MIT Haystack Observatory, the National Astronomical Observatory of Japan, the Perimeter Institute for Theoretical Physics, and the Radboud University.


Astronomers collaborated with renowned Hawaiian language and cultural practitioner Dr. Larry Kimura for the Hawaiian naming of the supermassive black hole at the centre of the galaxy M87. Pōwehi, meaning embellished dark source of unending creation, is a name sourced from the Kumulipo, the primordial chant describing the creation of the Hawaiian universe. Pō, profound dark source of unending creation, is a concept emphasized and repeated in the Kumulipo, while wehi, or wehiwehi, honored with embellishments, is one of many descriptions of pō in the chant. Dr. Kimura is an associate professor at University of Hawai‘i at Hilo Ka Haka ‘Ula o Ke‘elikolani College of Hawaiian Language.

Media Contacts

Geoff Bower
Chief Scientist for Hawaii Operations, ASIAA
Project Scientist, Event Horizon Telescope
Affiliate Graduate Faculty, UH Manoa Physics and Astronomy

Jessica Dempsey
Deputy Director of the East Asian Observatory (EAO) and JCMT

On sky operations to resume

After two months of hiatus in operations, we are pleased to announce that EAO will begin preparatory work to bring JCMT to on-sky operations. This decision comes after Hawaiʻi Governor David Ige identified the Observatories as part of the state’s list of low-risk organizations and businesses that are safe to reopen.

Recognizing the gravity of public health concerns over the global health pandemic and placing the safety of staff as paramount importance, the Observatory will continue to follow all health guidelines from state and local officials. The phased approach will include minimizing base facility activity and restricting summit work to only essential telescope operations, including critical maintenance of instrumentation and the facilities.

We will initiate operations in a limited on-site-staff mode, with most of our EAO staff continuing to work from home. We are putting into practice policies on hygiene and social distancing to ensure the safety of our staff and of our community here in Hawaii.

With safety our highest priority, we are nevertheless very happy to announce we will be returning to collecting the highest quality science to you, our JCMT user community. We thank you for your support during this time and ask that you keep engaging with us to help you bring your JCMT science to the world. The EAO `ohana continues to stay strong, healthy and optimistic, and we hope that you and your families continue to stay safe and well.

– with thanks, and on behalf of the entire EAO `ohana,


SMA fringe test with Nāmakanui a success

The JCMT had a successful fringe test yesterday with the SMA using the new instrument Nāmakanui; on loan at JCMT from ASIAA. The JCMT got fringes without problems which is really excellent news. This is good progress with an East Asian VLBI and Event Horizon Telescope run schedules in 2020. JCMT staff also confirmed the basic orientation of the lambda/4 plate – used for polarization measurements. Poor weather does mean there is still more to do, but congratulations to all involved. Staff are now looking to further testing of Nāmakanui at the EHT test run in January and for data taking during the March/April EHT campaign.

JCMT Operations Temporarily Suspended

Dear JCMT Community,

This week, the pending start of the construction of the Thirty Meter Telescope has sparked a protest which has blocked access to Maunakea for all traffic. Yesterday afternoon, the directors of the existing observatories made the joint decision to remove all personnel from their telescope facilities at the summit to guarantee the safety of their staff – the institutions’ top priority. Without guaranteed, reliable access to the telescopes, the Maunakea Observatories have suspended all summit activities (including remote operations) for the time being.

The safety of everyone on the mountain, MKO staff, law enforcement, and protestors is of paramount importance to us. We have voluntarily decided to remove our staff. This is not a decision we came to lightly, but want to emphasize the importance of safety for all staff and facilities.

We are truly grateful to the law enforcement offices who have been working around the clock to ensure the safety of everyone on Maunakea. The safety of our personnel – and of everyone on the mountain – remains our top priority.

We look forward to returning to normal operations as soon as the situation allows.

From the JCMT Team, Aloha and thank you for understanding.

EAO Futures meeting – a stepping stone to White Papers

The EAO Sub-mm Futures meeting held last week in Nanjing was a great success. All talks from the meeting are provided on the meeting program pages.

At the meeting the JCMT observatory had two major announcements:

1) The Observatory is seeking White Papers in support of a new 850 micron camera

The observatory seeks community input in the form of scientific White Papers in support of a new 850 micron camera for the JCMT. More information regarding the white papers will be provided at the EAO Futures Discussion wiki. Specifically White papers will be sought for:

The observatory is also soliciting for additional White Papers in addition to the above. All White Papers are to be submitted (visit the EAO wiki for a comprehensive list that have already been proposed). Deadline June 30th. A detailed description of the specification for the new 850 micron camera can be found here.

2) Announcing the JCMT Call for Large Programs (III)

The East Asian Observatory is pleased to provide an announcement of the third Call for JCMT Large Programs. At this time 4,800 hours will be available for Large Programs up until the end of the 2022B semester. This information is being provided ahead of the opening of the 20A Call in order for current and new teams to pursue discussion and planning. Submissions will be accepted from August 15th up until the September 15th deadline. This will likely coincide with the 20A PI Call. Fore more details click here. To reach the proposal handling system, Hedwig, and submit a proposal click here:

For further details visit our proposal web pages.

Supplementary Call for Proposals in Semester 16B

For the second successive summer, we have experienced unusually poor weather at the start of the B-semester, and we are facing a period of 7 weeks without SCUBA-2 in October and November, as it undergoes important maintenance. The combination of these events has severely impacted our supply of approved band-3/4 heterodyne programs.

We therefore invite new proposals to observe targets with 20h < RA < 04h with HARP and/or RxA, for immediate assessment, approval and execution.

See here for details; where the ‘Semester’ in question is called ’16X’.

You can reach the proposal handling system, Hedwig,  and find complete details of this Call at:

Any further questions should be directed to our helpdesk:

If this is your first visit to Hedwig, you should go to ‘Log in’ and generate an account. There is a ‘Help’ facility at the upper right corner, and individual Help tags at many other places.

This Call for Proposals closes on the 11th of October 2016. We welcome submissions now.

– 2016/09/27

Status of SCUBA-2

SCUBA-2 was recently returned to service after a 5-week-long absence due to a partial cryogen blockage. It has been returned to full service, despite requiring alternative operating conditions because of a problem diagnosed with one of the Pulse Tube Coolers. This issue has left the instrument filters at temperatures that are fractionally warmer than normal. SCUBA-2 operation will be maintained until October 5, when it will be removed from the telescope to replace the PTCs and also install new optical filters which we expect to improve the instrument performance. SCUBA-2 return to service is expected on or before November 24.

We apologize for the inconvenience and will keep you updated as to our progress.

– 2016/08/03

POL-2 information for 16B proposals

For potential PIs who wish to submit a POL-2 proposal for semester 16B (deadline 2016-03-16 01:00 UT), we have now prepared a brief guide page with details on the estimated sensitivity and observing mode of the instrument, at:

The Integration Time Calculator in Hedwig has also been updated. When performing a SCUBA-2 calculation, you can now select the POL-2 scan pattern POL-2 Daisy, to get a POL-2 time or noise estimate.

Please do remember, the 16B call for proposal closes in only 15 days!

JCMT announces new Deputy Director – Jessica Dempsey

We welcoming Jessica Dempsey to the role of Deputy Director of the JCMT. In addition to this we are proud to announce she has been also just been recognized with a Women Who Mean Business award for “Women to Watch”.


Jessica Dempsey receiving the award for “Women to Watch” March 2016.


Jessica Dempsey winner of “Women to Watch” 2016.

– 2016/03/01

Call for Proposals 16B

The East Asian Observatory is happy to invite PI observing proposals for semester 16B at JCMT (for details see here).

Semester 16B runs from 01 August 2016 to 31 January 2017. You can reach the proposal handling system, Hedwig,  and find complete details of this Call at:

New in 16A: the likely availability of POL-2. If you are interested
in doing polarimetry with SCUBA-2 please contact us at

If this is your first visit to Hedwig, you should go to ‘Log in’ and generate an account. There is a ‘Help’ facility at the upper right corner, and individual Help tags at many other places.

The 16B Call for Proposals closes on the 15th of March 2016.