JCMT Instruments

Additional Information

Continuum Observing

Status Active Instruments

RxA Operational

211 - 272 GHz Single Channel DSB SIS receiver

Occasional Baseline Problems

HARP Operational

325 - 375 GHz 16 Pixel SSB SIS receiver

12 of the 16 pixels are operational: H00, H01, H02, and H14 are dead.
Six new mixer block were installed in HARP late February. These replaced 4 unusable mixers and two mixers with excessive serial resistance. The replacement work went very well. However, the pixel H14 is still unusable due to oscillations. On 20091021 H00, H01 and H02 failed during bias testing. We are investigating when HARP can be opened up and the dead receptors replaced.

Occasional baseline problems

Sensitivity variations creating striping - worst at 13CO/C18O

RxW Operational

Dual channel SIS receiver operating 315-375 GHz (B-band) or 630-710 GHz (D-band). The B band is primarily intended for use with the SMA. HARP is in general supperior even for single point observations taking RxWB's two channels into account.

For D band observations SSB is strongly recommeded 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).

Only one mixer operational at B-band

Localized baseline ripple in PSSW mode.

SCUBA2 Commissioning

850 and 450 micron continuum camera.

5120 pixels (4 sub arrays x 1280 pixels) at each wavelength band.

Currently onder going system integration and testing using two commissioning grade sub arrays - one at each wavelength. Some problems has been found that are being resolved. The main issues are - magnetic sensitivity, worse than expected NEP at 850 and saturation of the 450 band

No or very limited science observing is planned with the commissioning grade arrays. Apart from the large number of non working pixels on the commissioning grade the sensitivity to variations in the earth magnetic field when the antenna moves in Azimuth has to be resolved before general use. This latter is being solved by improved magnetic shielding (in production, to be installed with the two first science grade arrays), a coil that activily cancels the earth magnetic field (being tested) and a servo that nulls the effect in the SQUID readout electronics (first version being tested). The main magnetic sensitivity comes from the input coil in column readout SQUID (SQ2). The 850 NEP is expected to be better on the science grade array. The loading of the 450 array will be resolved by a narrower band pass filter and by reduction of scattered light in the instrument. If the latter works well the origonal wider bandpass will be installed again.

First light August 22nd at 850 micron using a commissioning grade array. First light at 450 was an observation of Jupiter in December

Science operation with 1 sub arrays at each wavelength band expected summer 2009

Science operation with all arrays expected later in 2009

ACSIS Operational

16 channel correlator with up to 1.8 GHz bandwidth

RxA	Operational	211 - 272 GHz Single Channel DSB SIS receiver Occasional Baseline Problems
HARP	Operational	325 - 375 GHz 16 Pixel SSB SIS receiver 12 of the 16 pixels are operational: H00, H01, H02, and H14 are dead. Six new mixer block were installed in HARP late February. These replaced 4 unusable mixers and two mixers with excessive serial resistance. The replacement work went very well. However, the pixel H14 is still unusable due to oscillations. On 20091021 H00, H01 and H02 failed during bias testing. We are investigating when HARP can be opened up and the dead receptors replaced. Occasional baseline problems Sensitivity variations creating striping - worst at 13CO/C18O
RxW	Operational	Dual channel SIS receiver operating 315-375 GHz (B-band) or 630-710 GHz (D-band). The B band is primarily intended for use with the SMA. HARP is in general supperior even for single point observations taking RxWB's two channels into account. For D band observations SSB is strongly recommeded 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). Only one mixer operational at B-band Localized baseline ripple in PSSW mode.
SCUBA2	Commissioning	850 and 450 micron continuum camera. 5120 pixels (4 sub arrays x 1280 pixels) at each wavelength band. Currently onder going system integration and testing using two commissioning grade sub arrays - one at each wavelength. Some problems has been found that are being resolved. The main issues are - magnetic sensitivity, worse than expected NEP at 850 and saturation of the 450 band No or very limited science observing is planned with the commissioning grade arrays. Apart from the large number of non working pixels on the commissioning grade the sensitivity to variations in the earth magnetic field when the antenna moves in Azimuth has to be resolved before general use. This latter is being solved by improved magnetic shielding (in production, to be installed with the two first science grade arrays), a coil that activily cancels the earth magnetic field (being tested) and a servo that nulls the effect in the SQUID readout electronics (first version being tested). The main magnetic sensitivity comes from the input coil in column readout SQUID (SQ2). The 850 NEP is expected to be better on the science grade array. The loading of the 450 array will be resolved by a narrower band pass filter and by reduction of scattered light in the instrument. If the latter works well the origonal wider bandpass will be installed again. First light August 22nd at 850 micron using a commissioning grade array. First light at 450 was an observation of Jupiter in December Science operation with 1 sub arrays at each wavelength band expected summer 2009 Science operation with all arrays expected later in 2009
ACSIS	Operational	16 channel correlator with up to 1.8 GHz bandwidth