This week there have been a few press releases from the HET partners about our progress on the HETDEX survey so far. The graphical presentation of the data is amazing and the whole survey will represent a major accomplishment for observational cosmology once completed. Read more at the following links below.
Meanwhile, our hearts are with the radio astronomy community as they mourn the not-unanticipated structural failure of the Arecibo radio telescope this week. Send warm thoughts to all the large aperture telescopes being maintained out there – they are are precious tools to view the cosmos and is is quite sad to lose such a giant.
https://mcdonaldobservatory.org/news/releases/20201201
https://news.psu.edu/story/640405/2020/12/01/research/hobby-eberly-telescope-dark-energy-experiment-survey-begins-full
https://phys.org/news/2020-12-hetdex-track-probe-dark-energy.html
This week the VIRUS spectrograph reached another milestone with 70 active units on sky. Below is a reconstructed/magnified image of one observation (the units actually have gaps between them but are shown magnified here). White squares show the locations for 8 remaining units.
Each dithered VIRUS observation now contains 31,000 spectra covering 46 square arcminutes. Next stop: the full 78 units!
This week at the HET we have taken the top end of the telescope so that we can rework the layout of the IFU fibers and add 11 new fibers. That will leave just 17 IFU fibers to be installed. Just to be clear this is not spectrographs being installed but just the IFU fibers that feed future spectrographs. At the moment we have 41 spectrographs units installed and stable. This means we are not more than half way towards our total goal of ~78 units.
This week we are pleased to announce that a new VIRUS unit was installed in side two of the VIRUS enclosure. This brings us to 22 VIRUS units or 44 spectrographs. We also took a little time in the last engineering run to add on some valves to the vacuum fittings which will allow us to cold pump on the VIRUS units which takes far less time to do than to warm up and then repump which was our older methodology. Keeping 22 VIRUS units going is starting to be a little easier but still takes a lot of management.
In addition to the work on VIRUS, we have also installed in the coherent fiber bundles for the HPF. These coherent fiber bundles will be used to setup stars on HPF science fibers. HPF will arrive in the coming weeks and we are very excited to get our first high resolution instrument on sky in the coming months.
The next few days are going to be very busy at the HET. The HET team along with help from Austin will be installing IFU’s for the second virus enclosure in preparation for more virus units to be installed. This involves stringing fiber cables from the enclosure up to the top of the tracker to be attached to the IHMP (Input Head Mounting Plate). The team will also be investigating and trying to remedy problems with the IHMP dither mechanism. During this time there will be no science or engineering related night work due to immobility of tracker, structure or dome for the IFU deployment.
This week has been an exciting week ramping up to science. The Board of Visitor Staff Excellence Award Winners were announced by Director Armandroff and are as follows: Henry Cantu, Angela Davis, Steve Odewahn, and Trent Peterson. Congratulations to the winners.
We are quickly moving in to science mode with the upcoming new moon. Currently this week the first half of each night is being used primarily for science with the second half used for engineering due to the moon. The weather looks to be clearing over the holiday weekend, so hopefully we will be able to collect some good data for the HET community!
One of the many powerful thunderstorms that passed by us this month. This one produced hail just north of the HET.
This week we finally had a break in the stormy weather and started wave front sensor commissioning. A team from Austin came out and installed an imager and wave front sensor in the IHMP (Input Head Mounting Plate) to calibrate all other wave front sensors on the telescope. These devices once calibrated will help keep the tracker in perfect alignment with the mirror to optimize the observations we are taking for science. This will be the main focus for the next month. Hopefully the weather is more cooperative than it has been. If you would like to see a time-lapse of some of the recent storms follow this link: https://www.youtube.com/watch?v=shRD2WmPWd4
16 Virus units and their controllers lined up in the HET receiving bay. The controllers are the small boxes near the center of the image.
This week has been a busy one for the virus units at the HET. All of the virus units were removed from the enclosure, backfilled, pumped to vacuum and reinstalled. While doing this cooling fans were installed on all of the virus controllers to help keep the electronics cool. They hope that this will make the virus system a bit more stable.
The HET has been churning out lots of science during dark time this month as well. All groups that have submitted targets have received data!
In the past week we finished cleaning up the upper hex. In the process we had to move some of the cameras around in our internal views of the dome so the view located at:
http://het.as.utexas.edu/wfu might look a bit strange until we get around to moving the cameras back into place.
This week we will be starting the metrology of the upper hex in preparation for putting on the upper and lower X rails. This metrology is done with a laser tracker and small “nest” mirrors placed around the telescope structure. Other activities this week will include finishing up the cable-ways in the lower electrical room and spectrograph room, work on the structure azimuth cable wrap, and work on the static cable ways. It is amazing the amount of power wires, optical cables, glycol and air lines that need to be strung up.
We are still right on schedule.
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