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| TELESCOPE |
The telescope was shutdown between 31 March and April 10 for the lift and installation of SCUBA-2 into and onto the JCMT. |
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| SCUBA-2 |
Work on the installation of SCUBA-2 into the JCMT has progressed well. The teams from UK ATC and JAC are working on various aspects of the assembly and integration. The shutdown in May has been extended by a week, to accommodate aligning of the instrument. |
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| HARP/ACSIS |
The current status of HARP/ACSIS is summarised below:
- H03: missing from the cryostat since delivery.
- H14: currently unusable due to large oscillations in the mixer. This receptor has now been switched off in the data acquisition and so will appear blank in the data and real time displays at the telescope.
- Receptors H09 and H12 are operational but have high resistance in series with the junction.
- The performance of H09 has continued to deteriorate, especially at low frequencies, with the intermittent appearance of interference spikes in the spectra.
Because of these problems, data from receptor H09 below 340 GHz are now masked out by the pipeline processing (note that they are still in the original time-series spectra).
It is thought that the interference spikes we now sometimes see in receptor H09 could be due to oscillations in the mixer. This will be investigated in the next few weeks.
The situation with the receptor bias settings has not changed since previous reports (see below). The optimal bias settings are frequency dependent, e.g. variations are negligible around 370 GHz but at their worst at around 330 GHz. Work will soon begin on implementing a system where the bias level is set as a function of frequency. A real solution to this problem is being investigated by colleagues at MRAO (work on this should start in May). In the meantime, an interim software solution is being sought.
The cold head was replaced during the April shutdown. Early indications show that this was a succes with the instrument holding its temperature.
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| CALIBRATION |
In relation to the bias issues mentioned above, scans of the moon and beam maps of Mars have been taken which show that receptor-to-receptor variations are no more than 5%. The question now becomes why we see differences of more than 30% when observing line emission in molecular clouds. The answer, we believe, most likely lies with the variable performance of the bias curves.
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| JLS PROGRESS |
The April JLS observing block will be hosted by the NGS at the end of the month. See the summit occupancy page to see who the observers will be. Note that part of this block will be interrupted for eSMA and ROVER commissioning.
The telescope schedule for the rest of the semester has been finalised and teams should begin to organise their observers.
The current progress is shown in the bar charts below, illustrating the amount of time charged to each survey and the current completion rate (for just the HARP survey components). The NGS team have done a lot of their QA manually and this is reflected in the bar chart - they are currently almost 86% complete.
The JDUG are reviewing a proposal developed by the GBS team (based originally on a NGS document) to perform the majority of QA within the summit pipeline. We hope to start coding this at the end of the month.
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For reference, the JLS allocations are given here.
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| ARCHIVED REPORTS |
An archive of previous JLS status reports is accesible from the links below: |
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