Stars, Galaxies, and Fiber Optics

The first time I remember learning about fiber optics was in a behind-the-scenes article published in 1980 or so about the making of Star Trek: The Motion Picture. The article talked about how they got light to all the buttons on the bridge set and showed them illuminated with bundles of optical fiber. Nowadays, as I’ve mentioned in several earlier posts, I work with instruments that use optical fiber to carry light collected by each of the telescopes I work with to the instrumentation where its analyzed.

On the telescope side, those fibers are attached to an optical assembly that must be placed at just the right spot to catch focused light. If the star or galaxy is out of focus, not all the light goes down the optical fiber. We also have guider cameras that work to keep the object precisely aligned on the fiber so all the light gets to the spectrograph. It’s a lot of complex hardware to work right to precisely measure the the redshift of distant galaxies or look at a star and determine whether or not it has planets in orbit. This past week, we’ve been commissioning both the DESI spectrograph at the Mayall 4-meter and the NEID spectrograph at the WIYN 3.5-meter. One of the most important milestones is to get light from the object you want to measure to the spectrograph and see if you get the flux you expect. Here’s the NEID team at WIYN looking at early test results.

Yes, light leaves a star dozens of light years away, enters our telescope, goes down the optical fiber and is photographed with the spectroscope, then all that data can be viewed and analyzed on a laptop computer. When I filmed the trailer for The Astronomer’s Crypt a couple of years ago, I was asked why we didn’t use a room full of fancy computers and monitors. We just had a couple of computers, one of which was a laptop. The reason is that I’ve seen a lot of control rooms where simple computers are the only ones present!

As you can imagine, it’s quite a relief to see all the work pay off in a spectrum that shows the flux level you expect. All of this is pretty exciting stuff and, as it turns out, my birthday fell during this past week’s tests. Seeing NEID as it nears readiness for scientific use is pretty exciting in its own right, but we had another surprise on the day of my birthday. Ethan Peck, who plays Spock on Star Trek Discovery, was on a road trip and decided to visit the observatory. A tour was arranged and he spent the beginning of the night at the WIYN telescope. For me, it was quite a thrill to have Spock, of all people, wish me a happy birthday! He brought a Polaroid camera with him and we snapped a photo of us standing by my control station. Here we are at WIYN. Ethan Peck is in the center (in white) and I’m to the left.

Meanwhile, across the mountain at the Mayall 4-meter, commissioning has continued on the DESI instrument. The instrument had its official “first light” a couple of weeks ago and a wonderful image was released that, I think, really illustrates the power of DESI.

Image credit: DESI Collaboration, Legacy Surveys; NSF’s National Optical-Infrared Astronomy Research Laboratory/NSF/AURA

Here you see an image of all 5000 DESI fibers superimposed on the sky. At the bottom of the fiber array is M33, the Triangulum Galaxy. Below that is a view of the spectrum from just one of the 5000 fibers showing the light from that little piece of the galaxy. In it, you can see the lines labeled that denote the presence of hydrogen, oxygen, nitrogen, and even sulfur. Now remember that each fiber in that picture gives the same kind of data for the piece of sky its on. You can read the full press release about DESI’s first light at:

All of the robotic positioners moving those fibers at the top of the Mayall telescope get hot and there’s a chiller system to keep them cool. This week, that chiller system will be automated, but last week, we had to monitor it by eye and it requires a person to turn the system on and off by hand. The person doing that remarked how spooky it is to be in the depths of the Mayall with all the lights out and remarked how she kept looking over her shoulder, wondering if someone was there. This is another aspect of my job that definitely helped to inspire The Astronomer’s Crypt. You can learn more about the novel and see the trailer I mentioned earlier at http://www.davidleesummers/Astronomers-Crypt.html.