JCMT supports STEM Fest 2018 for Big Island Girl Scouts

The EAO Outreach Team was thrilled to be invited to help out at the 2018 STEM Fest event held in Waimea at the Kahilu Town Hall for Big Island Girl Scouts. The event, attended by 75 girls on November 17th, provided the opportunity to experience hands on activities from a variety of science and engineering fields.

JCMT staff members Alexis Achohido and Mimi Fuchs worked with Girl Scouts to discover how astronomers know what stars are made of. In particular we highlighted the work of  Cecilia Payne-Gaposchkin, who proposed a theory for the composition of stars in her 1925, her PhD Thesis!

As well as looking at what stars are made of we also looked at what dense interstellar dust clouds are made of and made our very own candy molecules.

Maunakea Gender Equity and Diversity Survey 2018 Report

In July 2018, the Maunakea Gender Equity and Diversity Committee distributed a survey to the staff at the Maunakea astronomical organizations. The survey was intended to invite opinion on the current state of equity and diversity in the Maunakea astronomy community and seed conversation and ideas for enhancing diversity and inclusion in our organizations across our islands.

The report on the results of the survey is here:

Maunakea Gender Equity and Diversity Survey 2018 Report

and the Appendix A, listing the survey questions, is provided for reference:

Gender Equity and Diversity Survey questions

The first results are presented by Jessica Dempsey at the Maunakea Users’ Meeting on October 4th, 2018. A PDF of the talk is linked here for convenience. For usage or distribution of these data, please contact Jessica Dempsey: j.dempsey “at” eaobservatory.org.

Photo by Oro Whitley

– 20181004


POL-2 data reduction fix for source blurring

POL-2 is the JCMT’s sub-millimeter polarimeter working at both 450 and 850 microns. POL-2 is a polarimeter not a detector, and so requires SCUBA-2 for use. It is used to trace the alignment of dust particles at sub-millimeter wavelengths and thus the magnetic field orientation and strength (with some additional physics added into the mix) of regions in our Universe!

Recently it has been found that sometime there is a loss of synchronisation between data values and pointing information in the data reduction process (CALCQU, run by pol2map as part of step 1). This loss of synchronisation is triggered by anomalous values in the array of HWP (Half Wave Plate) angles stored in the raw data. The result is blurring (or smoothing) of sources in some POL-2 maps (see figure below).

The fix is to download our rsync this build of the starlink software and re-reduce your data. If you look at your re-reduce data you may find that some of your maps improve, depending on whether any of your observations suffered from the blurring problem. The size of the improvement will depend on how many blurred observations you have.

For regions where multiple observations were used to produce the final maps the issue may have been less pronounced if obsweight=yes was used.

In addition, users wishing to reduce POL-2 450 micron data are asked to ensure the data have been reduced using the latest starlink 2018A software prior to this release there was a bug in the software which caused a 4 degree difference  in the angular zero point at 850 and 450, so all 450 vector maps produced so far will have a systematic error of 4 degrees in the vector angle, unless updated software (rsync starlink or 2018A starlink) was used.

The image shows two total intensity maps made from an observation of OMC1. Left: before the fix for blurring. Right: after the fix for blurring.

Also did you know you can combine various I maps into a cube to view as a movie? You can do this (assuming you ran pol2map with “mapdir=maps”) by running:


paste in=maps/\*Imap out=Icube shift=\[0,0,1\]

gaia Icube

Then in gaia, in the pop-up window that holds the cube visualisation controls, drag the “Index of plane” slider left or right to step through the planes in the cube!

You can do the same for the Q or U maps by replacing “I” with “Q” or “U” above (note, that’s an upper case “I” for the externally masked I maps – use a lower case “i” for the auto-masked I maps).

– 20180724

SMU work and data checks

In May our engineering staff undertook major maintenance work of the Secondary Mirror Unit on the JCMT. After this work it was noted that the Secondary mirror was sometimes vibrating, which lead to beam deformation. This was noticed due to sporadic increased FCF values – and could also be seen in the aspect ratio of our calibrators (see image below). Observers who collected data between UT dates May 24th 2018 and 08:10UT on June 30th 2018 should be aware of this issue. Astronomers who may have affected observations should check their data closely. This issue was noted to be intermittent. If you have questions about the data quality please contact your Support Scientist or the observatory directly.

On June 30th, we applied a temporary work-around to account for these SMU vibrations. To implement a more permanent solution, the observatory briefly removed the GoreTex membrane to work on the Secondary Mirror Unit. This work was performed between Tuesday July 24th, and Monday, July 30th.  The PI and Large Program time were unaffected.

Below is a plot showing the aspect ratios of calibrator CRL 2688 over time. The blue, shaded region represents the nominal values. Note that the high aspect ratios observed in between the temporary and permanent fix (boxed in red) were part of a low elevation, poor weather (wet grade 5), poor seeing engineering and commissioning project. Regular observing was unaffected.


 – 20180815

CHIMPS-2 members meet in Liverpool

Members of the CHIMPS-2 Large Program met for a two day meeting in Liverpool on June 28th and 29th. The meeting covered data collection, reduction and analysis with astronomers from all over the globe. For more information on the CHIMPS-2 project click here. We wish the team “clear skies” as they look to expand the JCMT CO heterodyne data towards the Galactic Centre this summer.

– 20180708

2018 OT update

We are always striving to do better at the JCMT and that means we often update our software. One software update that uses should be aware of is a new version of the JCMT Observing Tool.

It is particularly important to note that the OT version used for all semester 18B MSB preparation must be 20180516 (or newer). This may be checked via the OT start-up splash screen and also via the “Help -> About” menu option.

– 20180525

Engineering shutdown – May 2018

From time to time the JCMT is closed due to major maintenance work. The next scheduled closure of the JCMT will occur from April 30th 2018 to mid May 2018. During this time the Gore-Tex membrane windblind will be removed to provide access to the Secondary Mirror Unit for maintenance work. As the telescope will be unavailable for science during this time the SCUBA-2 Gas Handling System will also be worked on. SCUBA-2 will be warm during this period and should back to operational temperature/available for science use by the end of May.

– 20171201

Membrane removal scheduled for December 2017

The staff at EAO would like to announce that we are planning an approximately month-long observing campaign without our iconic Gore-Tex membrane windblind.

The removal of the membrane is due to the high demand for sub-mm polarimetry. Currently the instrument POL-2 is commissioned and working beautifully at 0.85mm, with some fantastic science results. POL-2 science at 0.85 mm has been so successful that we are keen to see if operating without the membrane – which can limit the throughput and increase instrumental polarization – we can commission POL-2 at 0.45 mm.

Observing without the membrane is not our normal mode of operation and the telescope will have additional operational limitations during this time. The JCMT will not take daytime observations and the operational wind limits will be reduced.

We expect to remove the membrane early in December and thank the JCMT astronomical community for their support.

– 20171122

Green Land Telescope Receiver testing progressing well at the JCMT

The Greenland Telescope (GLT) is a novel project; taking a 12-meter radio antenna – prototype for the Atacama Large Millimeter/Submillimeter Array (ALMA) project from Chile, and relocating this telescope to Greenland.

By repurposing this telescope astronomers can take advantage of the near-ideal conditions of the Arctic to study the Universe at specific radio frequencies. Whilst the telescope is being commissioned the initial receiver that will be used at the GLT is being tested at the JCMT in Hawaii. Last week the alignment of the instrument was performed this morning using the Sun as a source – and at the JCMT the first astronomical source for this instrument!

form more information visit: www.asiaa.sinica.edu.tw/project/vlbi.php and www.cfa.harvard.edu/greenland12m.

The GLT receiver installed inside the receiver cabin on the JCMT.

The inside of the GLT receiver

Delivery of the GLT receiver to JCMT

– 20170814