The next decade heralds a renaissance in radio astronomy, with a formidable complement of global Observatories, from LOFAR2.0, to the SKA becoming powerful discovery engines at these lowest frequencies. While they commit to lowering data access barriers, managing the deluge of data poses challenges, as the new constraint on viable astronomy must move from hours on sky to data product cost in energy, compute and carbon and data footprint. I will explore with you the challenges and opportunities in creating a new frontier of sustainable, ethical, affordable astronomy.
Auto-Correlation Spectral Imaging System (ACSIS) is an IF, correlation, reduction, and display system for the submillimeter telescope James Clerk Maxwell Telescope (JCMT). It can produce calibrated spectral images in real time and enables rapid imaging of large areas of the sky over a wide spectral range or at high resolution from up to 16 receiver feeds. Now more than 20 years old, the original 8-10GHz synthesizers for the down conversion module are obsolete and no longer available. Due to the hardware changes in the new 4-10GHz model, an interface circuit is needed to shorten the rise time of the serial clock signal. Further upgrades can better support wide IF band 2-12GHz receiver applications, such as Atacama Large Millimeter Array (ALMA) band-6 receivers. This paper discusses the observatory’s development of a new correlator that utilizes several existing electronics to support current and future receivers.
This Conference Presentation, “The Event Horizon Telescope: the impact of an image and finding Pōwehi,” was recorded for the Astronomical Telescopes + Instrumentation 2020 Digital Forum.
Most telescope proposal science cases are governed by the need to achieve a given SNR (Signal-to-noise ratio). However, traditionally telescopes award applicants a certain number of hours rather than an SNR or noise. Noise calculators cannot solve this problem entirely, due to variations in weather, elevation and instrument performance when an observation is actually carried out. The JCMT is currently shifting towards awarding users (when appropriate) a given RMS towards their source/s instead of a time spent observing, initially for our new 230 GHz instrument Ū ū. The JCMT already had many necessary parts of this process in place (noise calculators, a robust ‘live’ pipeline, and an extremely flexible queue based system). This presentation describes our efforts to start implementing this process for our users, discusses the necessary systems and software required, and describes the lessons applicable for other observatories.
The James Clerk Maxwell Telescope (JCMT) is the largest single dish telescope in the world focused on submillimeter astronomy - and it remains at the forefront of sub-millimeter discovery space. JCMT continues its push for higher efficiency and greater science impact with a switch to fully remote operation. This switch to remote operations occurred on November 1st 2019. The switch to remote operations should be recognized to be part of a decade long process involving incremental changes leading to Extended Observing - observing beyond the classical night shift - and eventually to full remote operations. The success of Remote Observing is indicated in the number of productive hours and continued low fault rate from before and after the switch.
In the age of Large Programs and Big Data a key component in project planning for ground-based astronomical observatories is understanding how to balance users demands and telescope capabilities. In particular, future planning for operations requires us to assess the impact of a complex set of parameters, such as right ascension, instrument, and sky condition pressures over coming semesters. Increased understanding of these parameters can provide: improved scientific output, better management of user expectations, more accurate advertised/allocated time under a Call for Proposals, and improved scheduling for instrumental commissioning and engineering work. We present ongoing efforts by staff at the James Clerk Maxwell Telescope (JCMT) to build a tool to provide automated completion forecasting of Large Programs undertaken at this telescope, which make up 50% of the observing time available at the JCMT.
We have fabricated new superconductor-insulator-superconductor (SIS) mixers chips for the 16-element Heterodyne Array Receiver Program (HARP) instrument on the James Clerk Maxwell Telescope (JCMT). The original spare mixer chips were limited and not performed as well as the used ones in HARP. The ability to manufacture new mixer chips would therefore be important for the repair and upgrade of HARP. Our immediate goal is to replace the current nonfunctional mixers in HARP with new chips. We modified the designs of waveguide probe and the matching circuit of the SIS mixer chip. The newly designed chips were fabricated with a quality factor (Rsg/Rn) over 10. The double-sideband (DSB) receiver noise temperature (Trx) is lower than 80K at frequencies between 325 GHz and 375 GHz, which is comparable to the best of the original devices. Three of the sixteen mixers have been replaced and they work very well.
Namakanui is an instrument containing three inserts in an ALMA type Dewar. The three inserts are ‘Ala’ihi, ‘U’ū and ‘Āweoweo 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.
The eight Maunakea Observatories continue to excel and expand but have traditionally been isolated facilities despite their close proximity to each other, with little formal sharing of human or technical resources. This has been changing recently, led by multi-telescope observing time swaps, budget challenges and the shared security pressures of Maunakea summit operations. Over the past two years, a series of Maunakea Operations and Engineering workshops have been held, discussing shared issues and novel ways of resource lending and sharing. The ideas and implementation of the first operations sharing initiatives that resulted will be presented, along with the lessons learned by reviewing the shared experiences of this wide range of highly productive facilities.
The James Clerk Maxwell telescope has operated on Maunakea for over thirty years. The Observatory has continually focused on integrated, database driven operations solutions to improve efficiency, data quality and publication productivity. In the past two years, a series of advances have been made to automate the analysis and display of critical Observatory metrics - including detailed project tracking, scheduling and completion, through to a new publications database which provides Observatory scientists with the tools to look critically at the rate of science return as a function of project, instrument, science area and other factors. These new tools will be presented, along with the results of the metrics analysis, and ways such tools can be adapted to other facilities.
A three-cartridge cryogenic receiver system is constructed for the Greenland Telescope Project. The system is equipped with a set of sub-millimeter receivers operating at 86, 230, and 345 GHz, as well as a complete set of instruments for calibration, control and monitoring. It is single pixel instrument built for VLBI observations. With the receiver system, the GLT has completed commissioning of its 12-m sub-millimeter antenna and participated in global very-long-baseline interferometry (VLBI) observations at Thule Air Base (TAB). This paper describes the receiver specification, construction, and verification.
The Greenland Telescope (GLT) project and the East Asian Observatory (EAO) successfully commissioned the first light GLT instrument at the James Clerk Maxwell Telescope (JCMT) in Hawaii, prior to transferring the instrument to Greenland. The GLT instrument which comprises of a cryostat with three cartridge-type receivers (at 86GHz, 230GHz and 345GHz) was installed into the receiver cabin of JCMT and operated in three modes: - (a) Regular JCMT observing with the GLT instrument, using ACSIS, (JCMT’s autocorrelation spectrometer) as the backend and JCMT software for telescope control, data reduction, pointing and antenna focus adjustment. (b) Single dish observations of astronomical spectral line sources, recording data onto mark 6 recorders for offline data reduction. (c) eSMA interferometer array observations at 230GHz in conjunction with the SMA. In this paper, we report on the installation and integration of the GLT instrument at JCMT, present results from commissioning and show how the success of the GLT instrument commissioning fits with our plans for future instrumentation at JCMT.
Sub-millimeter polarization observations using the POL-2 instrument mounted on the dual wavelength (850/450 μm) 10 k pixel sub-millimeter camera SCUBA-2 is in high demand on the James Clerk Maxwell Telescope (JCMT). The high level of Instrumental Polarization (IP) generated by the Gore-TexTM wind blind protecting the telescope is a hampering factor for these observations. The wind blind both introduces an overall linear polarization and a four lobed polarization footprint seen on strong point sources after removal of a beam averaged IP. During commissioning an IP model was developed for the 850 μm band but a good 450 μm model was lacking. This paper describes the effort to improve the 850 μm IP model, establish a 450 μm model and the work to understand and model the IP. During the work the wind blind was removed for a month to isolate the contribution of the wind blind from other sources of the IP. A theoretical model for the non wind blind generated IP has been developed. However, a theoretical model for the wind blind IP is still being worked on.
The Greenland Telescope project has recently participated in an experiment to image the supermassive black hole shadow at the center of M87 using Very Long Baseline Interferometry technique in April of 2018. The antenna consists of the 12-m ALMA North American prototype antenna that was modified to support two auxiliary side containers and to withstand an extremely cold environment. The telescope is currently at Thule Air Base in Greenland with the long-term goal to move the telescope over the Greenland ice sheet to Summit Station. The GLT currently has a single cryostat which houses three dual polarization receivers that cover 84-96 GHz, 213-243 GHz and 271-377 GHz bands. A hydrogen maser frequency source in conjunction with high frequency synthesizers are used to generate the local oscillator references for the receivers. The intermediate frequency outputs of each receiver cover 4-8 GHz and are heterodyned to baseband for digitization within a set of ROACH-2 units then formatted for recording onto Mark-6 data recorders. A separate set of ROACH-2 units operating in parallel provides the function of auto-correlation for real-time spectral analysis. Due to the stringent instrumental stability requirements for interferometry a diagnostic test system was incorporated into the design. Tying all of the above equipment together is the fiber optic system designed to operate in a low temperature environment and scalable to accommodate a larger distance between the control module and telescope for Summit Station. A report on the progress of the above electronics instrumentation system will be provided.
The Greenland Telescope Project (GLT) has successfully commissioned its 12-m sub-millimeter. In January 2018, the fringes were detected between the GLT and the Atacama Large Millimeter Array (ALMA) during a very-long-baseline interferometry (VLBI) exercise. In April 2018, the telescope participated in global VLBI science observations at Thule Air Base (TAB). The telescope has been completely rebuilt, with many new components, from the ALMA NA (North America) Prototype antenna and equipped with a new set of sub-millimeter receivers operating at 86, 230, and 345 GHz, as well as a complete set of instruments and VLBI backends. This paper describes our progress and status of the project and its plan for the coming decade.
The United Kingdom Infrared Telescope (UKIRT) observatory has been transferred to the ownership of the University of Hawaii (UH) and is now being managed by UH. We have established partnerships with several organizations to utilize the UKIRT for science projects and to support its operation. Our main partners are the U.S. Naval Observatory (USNO), the East Asian Observatory (EAO), and the UKIRT microlensing team (JPL/IPAC/OSU/Vanderbilt). The USNO is working on deep northern hemisphere surveys in the H and K bands and the UKIRT microlensing team is running a monitoring campaign of the Galactic bulge. EAO, UH, and USNO have individual P.I. research programs. Most of the observations are using the Wide Field Camera (WFCAM), but the older suite of cassegrain instruments are still fully operational. Data processing and archiving continue to be done CASU and WSA in the UK. We are working on a concept to upgrade the WFCAM with new larger infrared detector arrays for substantially improved survey efficiency.
The Greenland Telescope completed its construction, so the commissioning phase has been started since December 2017. Single-dish commissioning has started from the optical pointing which produced the first pointing model, followed by the radio pointing and focusing using the Moon for both the 86 GHz and the 230 GHz receivers. After Venus started to rise from the horizon, the focus positions has been improved for both receivers. Once we started the line pointing using the SiO(2-1) maser line and the CO(2-1) line for the 86 GHz and the 230 GHz receivers, respectively, the pointing accuracy also improved, and the final pointing accuracy turned to be around 3" - 5" for both receivers. In parallel, VLBI commissioning has been performed, with checking the frequency accuracy and the phase stability for all the components that would be used for the VLBI observations. After all the checks, we successfully joined the dress rehearsals and actual observations of the 86 GHz and 230 GHz VLBI observations, The first dress rehearsal data between GLT and ALMA were correlated, and successfully detected the first fringe, which confirmed that the GLT commissioning was successfully performed.
We describe the control and monitoring system for the Greenland Telescope (GLT). The GLT is a 12-m radio telescope aiming to carry out the sub-millimeter Very Long Baseline Interferometry (VLBI) observations and image the shadow of the super massive black hole in M87. In November 2017 construction has been finished and commissioning activity has been started. In April 2018 we participated in the VLBI observing campaign for the Event Horizon Telescope (EHT) collaboration. In this paper we present the entire GLT control/monitoring system in terms of computers, network and software.
Under the new operational purview of the East Asian Observatory, the JCMT continues to produce premier wide-field submillimetre science. Now the Observatory looks to embark on an ambitious series of instrumentation upgrades and opportunities to keep the telescope at the bleeding edge of its performance capabilities, whilst harnessing the collaborative expertise of the participating EAO regions and its JCMT partners. New heterodyne instruments include a new receiver at 230 GHz, a super array (90 pixels) at 345 GHz and the upgrade possibilities for the continuum camera SCUBA-2. In addition, the opportunities for PI and visiting instruments, including TimePilot and Gismo-2 will be described.
SCUBA-2 is a state of the art wide field camera on the JCMT. SCUBA-2 has been fully operational since November
2011, producing a wide range of science results, including a unique series of survey programs. A new large survey
programme commenced in 2015, which included for the first time, polarisation sensitive measurements using POL-2, the
polarimeter ancillary instrument. We discuss proposals and the science case for upgrading SCUBA-2 with new detector
arrays that will keep SCUBA-2 and the JCMT at the forefront of continuum submillimetre science.
As part of the JCMT Future Instrumentation Project, the EAO looks to optimize the premier niche of the facility as the
go-to telescope for fast, deep wide-field mapping of the universe at 345 GHz (850 um). The next generation heterodyne
array for JCMT will be designed to provide deep ultra-fast mapping capabilities that takes advantage of the full field-of-view
available to the telescope, and an array of 90 SIS mixers. This paper presents a preliminary design options and the
critical science drivers for the project.
The newly formed East Asian Observatory assumed operations of the James Clerk Maxwell Telescope in March of 2015. In just three weeks, the facility needed to run up completely mothballed observatory operations, introduce the telescope to a vast new scientist base with no familiarity with the facility, and create a non-existent science program. The handover to the EAO has since been a succession of challenging time-lines, and nearly unique problems requiring novel solutions. The results, however, have been spectacular, with subscription rates at unprecedented levels, a new series of Large Programs underway, as well as an exciting Future Instrumentation Project that together promises to keep JCMT at the forefront of wide-field submillimeter astronomy for the next decade.
instrument’s twin focal planes, each with over 5000 superconducting Transition Edge Sensors (TES) that work simultaneously at 450 and 850 microns are producing excellent science results and in particular a unique series of JCMT legacy surveys. In this paper we give an update on the performance of the instrument over the past 2 years of science operations and present the results of a study into the noise properties of the TES arrays. We highlight changes that have been implemented to increase the efficiency and performance of SCUBA-2 and discus the potential for future enhancements.
The James Clerk Maxwell Telescope (JCMT) is the largest single-dish submillimetre telescope in the world, and throughout its lifetime the volume and impact of its science output have steadily increased. A key factor for this continuing productivity is an ever-evolving approach to optimising operations, data acquisition, and science product pipelines and archives. The JCMT was one of the first common-user telescopes to adopt flexible scheduling in 2003, and its impact over a decade of observing will be presented. The introduction of an advanced data-reduction pipeline played an integral role, both for fast real-time reduction during observing, and for science-grade reduction in support of individual projects, legacy surveys, and the JCMT Science Archive. More recently, these foundations have facilitated the commencement of remote observing in addition to traditional on-site operations to further increase on-sky science time. The contribution of highly-trained and engaged operators, support and technical staff to efficient operations will be described. The long-term returns of this evolution are presented here, noting they were achieved in face of external pressures for leaner operating budgets and reduced staffing levels. In an era when visiting observers are being phased out of many observatories, we argue that maintaining a critical level of observer participation is vital to improving and maintaining scientific productivity and facility longevity.
The James Clerk Maxwell Telescope (JCMT) is the largest single dish submillimetre telescope in the world. Recently the Joint Astronomy Centre (JAC) has learned that the JCMT will no longer receive financial support from its original supporting agencies after September 2014. There is significant pressure to complete some surveys that have been in progress at the JCMT for many years now. With the goal of completing a higher percentage of these surveys it was decided to take advantage of the hours between when the telescope operator leaves the telescope and when the day crew arrives. These hours generally have reasonable seeing and low column integrated water vapor, so they are good for observing. This observing is being performed remotely, in Hilo, without staff at the telescope, by staff members who do not have telescope operation as part of their job descriptions. This paper describes the hardware changes necessary to implement remote observing at JCMT. It also describes the software needed for remote, fail safe, operation of the telescope. The protocols and rules for passing the control of the telescope between the various groups are discussed. Since these Extended Operators are not expert telescope operators, the system was simplified as much as possible, but some training was necessary and proper checklists are essential. Due to the success of the first phase of Extending Observing at the JCMT, the hours when the weather is good and no one is at the telescope, but no day crew is on the way, are also now being utilized. Extended Observing has already yielded a considerable amount of science observing time.
KEYWORDS: Data archive systems, Telescopes, Astronomy, Heterodyning, Calibration, Data modeling, Astronomical telescopes, Signal to noise ratio, Space telescopes, Observatories
The JCMT Science Archive is a collaboration between the James Clerk Maxwell Telescope and the Canadian Astronomy Data Centre to provide access to raw and reduced data from SCUBA-2 and the telescope’s heterodyne instruments. It was designed to include a range of advanced data products, created either by external groups, such as the JCMT Legacy Survey teams, or by the JCMT staff at the Joint Astronomy Centre. We are currently developing the archive to include a set of advanced data products which combine all of the publicly available data. We have developed a sky tiling scheme based on HEALPix tiles to allow us to construct co-added maps and data cubes on a well-defined grid. There will also be source catalogs both of regions of extended emission and the compact sources detected within these regions.
SCUBA-2 is the largest submillimetre wide-field bolometric camera ever built. This 43 square arc- minute field-of-view instrument operates at two wavelengths (850 and 450 microns) and has been installed on the James Clerk Maxwell Telescope on Mauna Kea, Hawaii. SCUBA-2 has been successfully commissioned and operational for general science since October 2011. This paper presents an overview of the on-sky performance of the instrument during and since commissioning in mid- 2011. The on-sky noise characteristics and NEPs of the 450 μm and 850 μm arrays, with average yields of approximately 3400 bolometers at each wavelength, will be shown. The observing modes of the instrument and the on-sky calibration techniques are described. The culmination of these efforts has resulted in a scientifically powerful mapping camera with sensitivities that allow a square degree of sky to be mapped to 10 mJy/beam rms at 850 μm in 2 hours and 60 mJy/beam rms at 450 μm in 5 hours in the best weather.
SCUBA-2 is a revolutionary 10,000 pixel wide-field submillimetre camera, recently commissioned and now operational
at the James Clerk Maxwell Telescope (JCMT). Twin focal planes each consist of four 32 by 40 sub-arrays of
superconducting Transition Edge Sensor (TES) bolometers, the largest combined low temperature bolometer arrays in
operation, to provide simultaneous imaging at wavelengths of 450 and 850 microns. SCUBA-2 was designed to map
large areas of sky more than 100 times faster than the original ground breaking SCUBA instrument and has achieved this
goal. In this paper we describe the performance of the instrument and present results of characterising the eight science
grade TES bolometer arrays. We discuss the steps taken to optimise the setup of the TES arrays to maximise mapping
speed and show how critical changes to the sub-array module thermal design, the introduction of independent focal plane
and 1K temperature control and enhancements to the cryogenics have combined to significantly improve the overall
performance of the instrument.
Commissioning of SCUBA-2 included a program of skydips and observations of calibration sources intended to
be folded into regular observing as standard methods of source flux calibration and to monitor the atmospheric
opacity and stability. During commissioning, it was found that these methods could also be utilised to characterise
the fundamental instrument response to sky noise and astronomical signals. Novel techniques for analysing onsky
performance and atmospheric conditions are presented, along with results from the calibration observations
and skydips.
This paper describes the key design features and performance of HARP, an innovative heterodyne focal-plane array
receiver designed and built to operate in the submillimetre on the James Clerk Maxwell Telescope (JCMT) in Hawaii.
The 4x4 element array uses SIS detectors, and is the first sub-millimetre spectral imaging system on the JCMT. HARP
provides 3-dimensional imaging capability with high sensitivity at 325-375 GHz and affords significantly improved
productivity in terms of speed of mapping. HARP was designed and built as a collaborative project between the
Cavendish Astrophysics Group in Cambridge UK, the UK-Astronomy Technology Centre in Edinburgh UK, the
Herzberg Institute of Astrophysics in Canada and the Joint Astronomy Centre in Hawaii. SIS devices for the mixers were
fabricated to a Cavendish Astrophysics Group design at the Delft University of Technology in the Netherlands. Working
in conjunction with the new Auto Correlation Spectral Imaging System (ACSIS), first light with HARP was achieved in
December 2005. HARP synthesizes a number of interesting features across all elements of the design; we present key
performance characteristics and images of astronomical observations obtained during commissioning.
A 183GHz water vapour radiometer is installed at the JCMT, but is not currently used for active atmospheric
calibration. With the installation of the SCUBA-2 submillimetre camera, it is desirable to provide more accurate
and time-sensitive calibration at specific wavelengths. It is shown here that the 183GHz water vapour monitor
data can be used to calculate the atmospheric opacity over small time-scales, directly along the line-of-sight of
the instrument. These data will be used to identify the potential for improvement in existing calibration schemes,
and the requirements of such a system if used with an instrument such as SCUBA-2.
The Antarctic Fiber-Optic Spectrometer (AFOS) is a 30cm Newtonian optical telescope that injects light through six 30m long optical fibers onto a 240-850nm spectrograph with a 1024 x 256 pixel CCD camera. The telescope is mounted on a dual telescope altitude-azimuth mount and has been designed to measure the transperency of the atmosphere above the South Pole for astronomy in the UV and visible wavelength regions. The instrument has observed a series of bright O and B stars during the austral winters of 2002 and 2003 to probe the UV cutoff wavelength, the auroral intensity and water vapour content in the atmosphere above the plateau. AFOS is the first completely automated optical telescope on the Antarctic Plateau. This paper reports on the results of the past two austral winters of remote observing with the telescope as well as the technical and software modifications required to improve the quality and automation of the observations. The atmospheric absorption bands in the 660-900nm regions of the spectra have been fitted with MODTRAN atmospheric models and used to calculate the precipitable water vapour above the South Pole. These data are then compared to those collected concurrently by radiosonde and by a 350 μm submillimeter tipper at South Pole.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.