This page lists the current operational instruments available to users at the JCMT. A brief summary of their current status can be found at the bottom of this page.
The JCMT currently has two heterodyne receivers in operation: Receiver A3 (also known as RxA): 230 GHz, single-pixel DSB receiver and HARP: 345 GHz, 16-pixel array receiver. The backend for both receivers is the ACSIS correlating spectrometer.
Plot of transmission as a function of frequency for different levels of precipitable water vapor. The two current heterodyne receivers HARP and RxA are shown in relation to this.
SCUBA-2 is the JCMT’s continuum camera. I has four 32×40 detector arrays at 850 and 450 micron, in total 10240 detectors.
Plot of transmission as a function of frequency for different levels of precipitable water vapor. The SCUBA-2 450 and 850 micron filters are shown in relation to this. It is clearly evident that 450 micron data requires good weather conditions due to the atmospheric window.
- 850 and 450 micron continuum camera.
- 5120 bolometers (4 sub arrays x 1280 bolometers) at each wavelength band.
- Currently about 3500 bolometers are working at each wavelength band.
- 325 – 375 GHz 16 detector SSB SIS array receiver
- Currently HARP cannot be tuned to frequencies 325-329 GHz LSB and 335 – 339 GHz USB.
- 14 of the 16 receptors (detectors) are operational: H13 and H14 are not operational.
- The lack of two receptors hampers jiggle mapping. Work is ongoing replace the broken receptors. The largest square fully sampled field of view with a HARP jiggle map is currently 1.5’x1.5′. If the full 2’x2′ jiggle field of view is required we recommend to use a small raster instead (114″x114″ 1/4 array spaced basket weaved). This will be less efficient with a factor of about 1.5 in time.
- Sensitivity variations creating striping – worst at 13CO/C18O
- 211.5 – 276.5 GHz Single Channel DSB SIS receiver
- In 2016 the mixer was replaced by an SMA mixer and as a result sideband ratios are different from 1.0 at certain LO frequencies. This was also the case for the replaced mixer. It is planned to apply corrections in the data reduction.
- After replacement of the old 1980s micro computer, frequency switching has not been implemented.
- 16 channel correlator with up to 1.8 GHz bandwidth.
- 183 GHz water vapour monitor installed in receiver cabin.
- Measures the precipitable water vapour along the line of sight at 1.2 second intervals.
- Of the two WVMs available the black WVM is currently installed.
- For D band observations SSB is strongly recommended even if DSB mode is possible. The DSB option has been removed in the latest OT version.
- For D band, channel A is displaced by 10″ on the sky from channel B (which is the tracking receptor).
- Localized baseline ripple in PSSW mode.