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 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.
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 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.
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.
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