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.
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.
SCUBA-2 has been operational on JCMT producing excellent science for almost 5 years. We describe the strategy and
methods that we have evolved to keep one of the world’s first “dry dilution refrigerators” and the other cryogenic
systems working effectively at the summit of Mauna Kea, keeping the instrument functioning at peak efficiency for
extended periods (over 12 months at a time), with minimum downtime. We discuss new plans to reduce day-to-day
operational costs and to add remote management of the gas handling systems, as we look to the future and envisage
another ten years of SCUBA-2 science.
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.
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.
We present the latest commissioning results and instrument performance for the SCUBA-2 imaging Fourier Transform Spectrometer (FTS-2) installed at the James Clerk Maxwell Telescope (JCMT). This ancillary instrument provides intermediate spectral resolution (R ~10 to 5000) across both the 450 and 850 μm atmospheric transmission windows with a FOV of ~5 arcmin2. The superconducting TES sensors and SQUID readout of SCUBA-2 present unique challenges for operation of an FTS; the sensitivity requirements demand high detector linearity and stability in addition to control of systematic atmospheric and optical spillover effects. We discuss the challenges encountered during commissioning and ongoing efforts to mitigate their effects.
SCUBA-2 is a wide-field submillimeter bolometer camera operating at the James Clerk Maxwell Telescope. The camera has twin focal planes, each with 5120 superconducting Transition Edge Sensors, which provide simultaneous images in two filter bands at 450 and 850 microns matched to the atmospheric windows. Detailed knowledge of the optical filter profiles that define these bands is important for estimating potential contamination from the prevalent CO J = 3-2 and CO 6-5 line emission, and correctly interpreting the effects of the source spectral index on photometric observations. We present measurements of the spectral response of SCUBA-2 obtained with FTS-2, the ancillary Fourier transform spectrometer instrument at the JCMT. The spectral measurements will be compared with the predicted filter profile determined from the linear combination of the individual filter profiles present in the SCUBA-2 optical train.
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.
Cryogen free or ‘dry’ dilution refrigerators that integrate a cryocooler such as a two stage pulse tube to replace the conventional liquid helium bath and 1K pot, have become a practical alternative for cooling astronomical detectors to mK temperatures and offer many advantages. SCUBA-2, the new submillimetre camera in operation at the JCMT, on the summit of Mauna Kea, Hawaii, was one of the first instruments to use such a fridge design. The dry dilution fridge for SCUBA-2 has now been in service for almost 4 years during commissioning at JCMT. In the most recent astronomical commissioning phase, the dilution fridge was in continuous operation for 10 months with no loss of base temperature or cooling power, cooling the SCUBA-2 detector arrays to below 100mK while maintaining a further 100Kg of enclosure, shields and SQUID amplifiers at 1K. In this paper we review some of the lessons from operating a dry dilution fridge at the JCMT and the necessary changes that have been incorporated. We present the performance of the fridge and discus its role in ensuring the success of SCUBA-2.
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.
SCUBA-2 is a state of the art 10,000 pixel submillimeter camera installed and being commissioned at the James Clerk
Maxwell Telescope (JCMT) providing wide-field simultaneous imaging at wavelengths of 450 and 850 microns. At each
wavelength there are four 32 by 40 sub-arrays of superconducting Transition Edge Sensor (TES) bolometers, each
packaged with inline SQUID multiplexed readout and amplifier. In this paper we present the results of characterising
individual 1280 bolometer science grade sub-arrays, both in a dedicated 50mk dilution refrigerator test facility and in the
instrument installed at the JCMT.
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
Over preceding conferences, the design and implementation of the SCUBA-2 (Sub-millimeter Common-User
Bolometric Array 2) instrument hardware has been described in detail. SCUBA-2 has been installed on the James Clerk
Maxwell Telescope (JCMT) for over two years and its hardware has been successfully commissioned. This paper
describes the culmination of this process and compares the optical/mechanical design and test expectations of the
instrument hardware against the performance achieved in the field.
SCUBA-2 is a new wide-field submillimeter continuum instrument being commissioned on the James Clerk
Maxwell Telescope on Mauna Kea in Hawaii. SCUBA-2 uses large-scale arrays of superconducting bolometers
with SQUID- (superconducting quantum interference device) based multiplexing and amplification. The sensitivity
of the devices that compose the detector arrays to magnetic fields is such that magnetic shielding, consisting
of superconducting and high-permeability materials, was fitted to the detector enclosure at 1 K to reduce the
magnetic field strength at the focal plane. This paper describes the design and construction of the cryogenic
shielding, and presents verification measurements. The shielding performance was found to meet the instrument
requirements, and compared well to the modelled results.
The detector arrays for the SCUBA-2 instrument consist of TES bolometers with superconducting amplifier and
multiplexing circuits based on Superconducting Quantum Interference Devices (SQUIDs). The SCUBA-2 TES arrays
and their multiplexed SQUID readouts need to be set-up carefully to achieve correct performance. Algorithms have been
developed and implemented based on the first available commissioning grade detector, enabling the array to be set up
and optimized automatically.
SCUBA-2 is a new wide-field submillimeter continuum instrument being commissioned on the James Clerk
Maxwell Telescope on Mauna Kea in Hawaii. SCUBA-2 images simultaneously at 450 and 850 μm using large-scale
arrays of superconducting bolometers, with over five thousand pixels at each wavelength. The arrays are
cooled to less than 100 mK by the mixing chamber of a dilution refrigerator (DR), with a radiation shield at a
nominal temperature of 1 K cooled by the DR still. The DR is a "dry" system, using a pulse tube cooler for
precooling of the circulating helium in place of a liquid helium bath. This paper presents key performance data
for the DR.
We present the results of characterization measurements on a 1280 pixel superconducting bolometer array designed for operation at wavelengths around 450 μm. The array is a prototype for the sub-arrays which will form the focal plane for the SCUBA-2 sub-mm camera, being built for the James Clerk Maxwell Telescope (JCMT) in Hawaii. With over 10 000 pixels in total, it will provide a huge improvement in both sensitivity and mapping speed over existing instruments. The array consists of molybdenum-copper bi-layer TES (transition edge sensor) pixels, bonded to a multiplexer. The detectors operate at a
temperature of approximately 175 mK, and require a heat sink at a temperature of approximately 60 mK. In contrast to previous TES arrays, the multiplexing elements are located beneath each pixel (an "in-focal plane" configuration). We present the results of electrical and optical measurements, and show that the optical NEP (noise equivalent power) is less than 1.4 × 10-16 W Hz-0.5 and thus within the goal of 1.5 × 10-16 W Hz-0.5.
SCUBA-2 is an innovative 10,000 pixel submillimeter camera due to be delivered to the James Clerk Maxwell Telescope in late 2006. The camera is expected to revolutionize submillimeter astronomy in terms of the ability to carry out wide-field surveys to unprecedented depths addressing key questions relating to the origins of galaxies, stars and planets. This paper presents an update on the project with particular emphasis on the laboratory commissioning of the instrument. The assembly and integration will be described as well as the measured thermal performance of the instrument. A summary of the performance results will be presented from the TES bolometer arrays, which come complete with in-focal plane SQUID amplifiers and multiplexed readouts, and are cooled to 100mK by a liquid cryogen-free dilution refrigerator. Considerable emphasis has also been placed on the operating modes of the instrument and the "common-user" aspect of the user interface and data reduction pipeline. These areas will also be described in the paper.
The SCUBA-2 instrument is a new wide field submillimeter imager currently being designed for the James Clerk Maxwell telescope on Mauna Kea in Hawaii. The instrument will observe simultaneously in the 450 and 850 micron bands and has a field of view of approximately 50 square arcminutes. To meet the performance requirements the detectors require a heat sink at a temperature of 50 mK or lower, and must be surrounded by an enclosure at a temperature of 1.1 K or below.
Cooling is provided by the mixing chamber and still of a cryogen-free dilution refrigerator (DR), via thermal links of the order of a metre in length. A challenging set of requirements result from the need for a small temperature drop between the detectors and the refrigerator insert despite the large distance between them, the need to provide flexibility in the links to allow for movement during thermal contraction, and the need to allow for the detectors to be
removed from the cryostat. Further, the arrays require a mounting structure which provides rigid mechanical support from the 1-K stage yet causes a very small heat input to millikelvin stage. This paper describes the design which has been evolved to meet these difficult (and often conflicting) requirements.