Summer Shutdown 2021

I returned to work on site at Kitt Peak National Observatory in November 2020. Social distancing regulations were put in place along with several other protocols to minimize the risk of COVID-19 infection. In that time, we’ve been making great strides commissioning the DESI spectrograph and starting it’s five-year survey, which is intended to result in the most comprehensive 3D map of the universe yet made. The instrument is already getting results. For those who don’t recall earlier posts about DESI, it has 5000 optical fibers mounted at the prime focus of the Mayall 4-meter telescope. Each fiber can be positioned to align precisely with an object on the sky. The fibers run to a spectrograph where the light is analyzed and redshifts of distant objects such as galaxies and quasars can be measured. The following image shows how much sky DESI gets in one pointing. It shows the nearby Andromeda Galaxy taking up much of the field, but as an example, you see that one fiber has landed on a distant quasar. It’s spectrum is displayed in the inset box. Each of the pizza-slice segments represents the 500 fibers in one petal of the DESI instrument.

The disk of the Andromeda Galaxy (M31), which spans more than 3 degrees across the sky, is targeted by a single DESI pointing, represented by the large circular overlay. The smaller circles within this overlay represent the regions accessible to each of the 5000 DESI robotic fiber positioners. In this sample, the 5000 spectra that were simultaneously collected by DESI include not only stars within the Andromeda Galaxy, but also distant galaxies and quasars. The example DESI spectrum that overlays this image is of a distant quasar that is 11 billion years old. Credit: DESI collaboration/DESI Legacy Imaging Surveys/LBNL/DOE & KPNO/CTIO/NOIRLab/NSF/AURA/unWISE

Summer in Arizona is monsoon season. In short, we get a lot of rain. Clear skies can be few and far between. As a result, this is the time of year engineers often choose to shut down the telescopes to do maintenance and make modifications. The DESI instrument has been performing well, but that doesn’t mean it can’t be improved. The fibers in each of those pizza-slice shapes are aligned by a system called the “Command Action Network” or CAN-Bus for short. It was determined that the CAN-Bus system in DESI could be improved. To do this, each petal has to be removed from the Mayall’s prime focus and placed in an area where it can be worked on. We’re able to do this work this summer because of the availability of COVID vaccines. We do take care to practice social distancing where possible and, especially in the wake of the Delta variant’s rise, we’re staying masked throughout the day. This next photo shows DESI with four of the petals removed.

DESI opened up. The red device in the foreground is used to carefully extract the petals.

The trickiest part of this operation is that the DESI petals are all attached by several yards of fiber optic cable to the spectrographs two stories below. When we remove the petals, we don’t want to torque or strain those cables too much. The petals are lifted down and placed on the floor beside the telescope. Once there, they’re placed into clean tents where they’re worked on. Here we see two members of the DESI team diligently working on the CAN-Bus electronics behind the fiber positioners.

Working on the petals. The fiber optic cables come out of the tent, run along the top and then over the rail to the spectrographs below.

Finally when all the new electronics are installed, the petals have to be tested. Among other things, we need to make sure we didn’t break any of the fibers as we handled the petals. DESI is designed to be able to shine light from the spectrograph up through the fibers. We call these “back illuminators” and a camera mounted just below the telescope’s primary mirror can take an image of the back illuminated fibers to see what position they’re in. Here we see the petal out of the telescope with the back illuminators turned on.

DESI’S fibers glowing a friendly blue, telling us all is well after the work has been completed.

Once the upgrades are completed, the petals are reattached to the telescope. This is a big collaborative effort involving many people from around the country and around the world. Once it’s done, we should have made what was already a powerful machine designed to answer questions about dark energy into an even more powerful machine.

Once More Unto the Breach

On the early hours of March 16, I walked out of the Mayall 4-meter telescope at Kitt Peak, aware that the world had been gripped by the COVID-19 pandemic, but thinking I would be back for my next normal shift. After all, a facility like Kitt Peak needs maintenance and care even when things were shut down and my team, the observing associates, were one group standing by to fill that role.

As the following week wore on, plans evolved. The number of people who would be on site would be significantly scaled back. Engineers were ordered to ready the telescopes and instrumentation at the observatory for a long-term shutdown. A very small skeleton staff would come to the mountain to maintain those systems that required attention. My team would work from home.

As it turns out, I had a productive spring and summer. One major job was creating a plan for safe reopening. Unfortunately, right as we started discussions of this plan, cases of COVID-19 began to rise dramatically in Arizona. We made our plan. It was reviewed by upper management and then we waited for cases to go down again. While waiting, I made strides on improving the operations manual for the Mayall 4-meter telescope. Not only did I revise it to discuss updated software for moving the telescope, I took some online courses in Cascading Style Sheets and Javascript and put those skills to use modernizing the look of the manual. It’s even mobile friendly, now, though I suspect that’s a function that won’t get much use! Still, we do have limited wireless in the building and I can imagine a future when people might access the site on phones or tablets.

David at the Mayall

On November 6, I returned to the Mayall telescope. I was the last operator to work during a commissioning run for the Dark Energy Spectrographic Instrument. I would be the first operator to wake up the sleeping giant and put it through its paces with some pointing and tracking tests. It turned out, after several hot, dry months, we found ourselves with a stormy weekend. Winds gusted as high as 75 miles per hour. We had fog, rain, and even snow. Despite that, we did have a few clear hours. We actually haven’t opened up the main mirror on the telescope. We only used a small pointing camera mounted to the telescope’s side, but it’s good to know the telescope still can point to targets on the sky as it’s designed to. We tracked a few targets for extended times. After my shift finishes, other observing associates will work with the DESI commissioning team to get the spectrograph itself running again. It should not be long before commissioning resumes and hopefully not long after that before the telescope begins regular science.

One thing that has been a challenge, is getting used to working within “bubbles.” As I’ve noted in posts before the shutdown, the telescope operators, DESI scientists, and any needed engineers would gather together in one big control room to do the night’s work. Since I’ve been back, I haven’t even stepped into the new Mayall control room. I’ve done all my work from the old console room, we though abandoned many months ago.

Working in the Old Console Room again.

A lead observer works alone in the new console room and we communicate using conferencing software. My meals are still prepared by the Kitt Peak cafeteria, but they’re delivered to the console room before I arrive. I get to heat them up in the microwave. So my days are mostly going between my dorm room and the console room. In the few times a night I do need to venture forth, I don my mask and check on the radio to make sure I’m not going to get within six feet of another person. It’s a little awkward, but not too different from working with observers who have signed in to work from their home institutions.

All in all, it’s a challenge getting used to this “new normal” while remembering everything required to operate the telescope. Still, it’s good to resume science operations. Shakespeare’s Henry V might look at us getting ready to resume science operations and say: “I see you stand like greyhounds in the slips, Straining upon the start.”

Chargers

No, this isn’t a post about a football team that started in Los Angeles, moved to San Diego, then returned to Los Angeles. This past week, I operated the WIYN telescope at Kitt Peak National Observatory. About halfway through the week, the charger circuit on the telescope failed. The WIYN is a telescope with a 3.5-meter primary mirror, making it the second largest aperture optical telescope at the observatory. This large telescope needs to track the sky as smoothly as possible to get the precise measurements we make of astronomical objects. Because of that, the motors don’t actually work off a power cord plugged into the wall that could be subject to brown outs or power spikes. Instead, we have a charger circuit that charges up a set of small batteries. The telescope drives actually are powered by the batteries, shown in the photo to the left.

Although I have some experience with electronics, I’m not actually an electrical engineer. When failures like this occur, my job is less to make a repair, but to see if I can find a way to limp along for the rest of the night and continue to take data in spite of the trouble. However, the circuit is so fundamental to the telescope’s operation and the problem bad enough that I couldn’t even limp along. We had to close up and wait for more expert help in the daytime.

Fortunately, our expert electronics crew was able to repair the charger circuit in less than a day, so we were back on sky and taking spectra of galaxy clusters the next night. What has always amazed me about the charger circuit on the WIYN telescope is that a bank of relatively small batteries can move a 3.5-meter telescope. Those batteries need to move the telescope in three axes. The obvious axes are altitude and azimuth. As WIYN tracks the sky, images rotate in the field of view, so there’s also a rotator that keeps north up in the images.

The charger system strikes me as a metaphor for my approach to seeking inspiration for my writing. The charger system takes current from the wall in whatever form it exists, uses it to charge batteries, which change the form of the current to produce good telescope motion. I take inspiration from my work in astronomy, from the books I read, the movies I see, and my time interacting with friends and family, allow myself to process that through my brain and turn that into the stories and novels I write.

I have taken variable star data with telescopes that use wind-up clock drives and that has helped to inspire and inform clockwork gadgets in my steampunk stories. I once helped an astronomer to take one of the deepest images of the center of our galaxy in the infrared, which helped me to imagine a voyage to the center of the galaxy in my Space Pirates’ Legacy novels. Working late nights on a lonely mountain top in meandering buildings informs my horror. If you’re a writer, I’d love to hear about some things that have inspired your writing in the comments below.

Explore the worlds I’ve created at http://www.davidleesummers.com