HARP
As part of my
PhD, I worked on commissioning HARP (Heterodyne Array
Receiver Project), a new array spectrograph for the
JCMT. HARP allows the kinematics of dense, warm gas to
be probed at matched resolution to the JCMT's continuum
receivers SCUBA(-2). The HARP imaging array comprises 16 SIS
mixers in a 4x4 grid, separated by 30 arcsec at
frequencies between 325 and 375 GHz. Its main
advantage is over an order of magnitude increase in
mapping speed, which allows data to be collect on
degree-scales rapidly. More information can be found
in Smith et
al. (2008) and the HARP/ACSIS instrument paper (Buckle et
al. 2009).
HARP Calibration
In my PhD data, I found prominent striping artefacts, which remained after all normal data reduction procedures. These seemed to be related to certain receptors in the HARP array having systematically lower and higher intensities. To remove these variations in molecular cloud data I derived 'gains' for each receptor based on the total flux seen towards the entire cloud. These artefacts are seen in other HARP datasets (although thankfully not any more) and my method is being used by the Gould Belt Survey on their similarly stripey data. The full technique is described in Chapter 4 of my thesis and Curtis, Richer & Buckle (2010). The two figures below show before and after the algorithm is applied to 13CO data in NGC 1333.
eSMA
The eSMA
is a new collaborative telescope, where three
facilities on Mauna Kea, Hawai'i (the JCMT, SMA and CSO) join forces to
act as a single interferometer. As part of my PhD I
helped to re-design the JCMT's high-frequency receiver
(RxW) to operate as part of the eSMA, using HARP-design mixers and a new optics
arrangement. For further information on the eSMA see
Bottinelli et
al. (2008), while the re-design is described in Chapter 3 of my thesis.
Facilities that constitute the eSMA, from left
to right the CSO, JCMT and SMA.