observing

Shooting for the stars

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Just like any other field of science, astronomy has had its share of colorful characters over the years. One of the more recent ones was no doubt Fritz Zwicky (1898-1947). Zwicky was a Swiss astronomer, who came to California Institute of Technology as a graduate student, and ended up as a full professor, spending the rest of his life in Pasadena.

Zwicky was known for his antics and sometimes odd behaviour, both during social gatherings, but also during scientific work. In terms of the latter, one could probably consider him thinking very far outside the box. One of the more famous episodes happened during a night of observing with the 200″ Hale telescope at Mt. Palomar Observatory;

One of the challenges when observing objects close to the Earth, is the ability for the telescopes to track fast-moving objects. You want your telescope to be able to move fast across the sky. At the same time, it needs to move smoothly enough so that the object you are tracking stays on the same spot on your detector. This is far from trivial, and even with modern telescopes, accurate tracking of near Earth objects can be quite challenging.

In the days of Fritz Zwicky this was even more true than today. And understandably it was of interest to determine just how fast and accurate it was possible to track objects with the Hale Telescope. Zwicky took an somewhat unconventional approach to testing this.

The 200-inch Hale Telescope at Palomar Observatory

The 200″ Hale Telescope. Photo credit: Palomar/Caltech.

Together with his night assistant, Ben Traxler, he conducted an experiment, where several shots were fired with a rifle out through the dome slit. Zwicky would then attempt to track the bullets with the Hale Telescope. There are no reports as to how successful this experiment was, but  it is definitely an example of Zwicky’s outside-the-box thinking. The incident did however, result in Zwicky being temporarily banned from using the Hale telescope.

On the other hand, his way of thinking did lead to groundbreaking research in supernovae amongst other things. He also proposed several ideas that were subsequently confirmed, like neutron stars, gravitational lensing and dark matter, many of which were not taken seriously at the time.

To my knowledge, Zwicky has been the only astronomer who was literally “shooting for the stars”. Which should probably be considered a good thing.

Thanks to Barbarina Zwicky for providing details for this story.

The casket with an IMPACT

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Most astronomical instruments do not come in anything that resembles standard shapes and sizes of normal cargo. It’s not like you go down to the local post office and ask for “one of those boxes for shipping satellites you have out back”. Getting the instruments from A to B usually requires a little more effort, as it is sensitive equipment, often in odd shapes. But sometimes you are in the lucky situation where a more ordinary container can be used with success.

Stereo1_med

Artists’ illustration of one of the STEREO satellites. Photo credit: NASA STEREO

In October 2006, NASA launched the STEREO mission, which consists of two, nearly identical satellites, with the purpose of making stereoscopic observations of the Sun to study, for instance, coronal mass ejections and other Solar phenomena. But first the satellite and the instruments on board had to be assembled, which involved shipping some instrument parts in… non-standard containers.

The IMPACT instrument, which is used to study the energetic particles from the Sun, is mounted on a large extendable boom that would be deployed after the satellite had launched. But first the boom and the instrument had to get to the facility where the satellite would be assembled.

On one of many travels from a STEREO meeting, the IMPACT project manager, Dave Curtis, and IMPACT engineer Jeremy McCauley were discussing the status of the instrument. They had come up with a stable and functional design for the boom, but schedule was getting tight. The boom had to be sent to Los Angeles for testing, only a few weeks in the future.

Jeremy had been running the preliminary design numbers and figured that they needed a roughly man-sized box to transport the boom. To this, Dave quipped, “Wouldn’t it be great if we could just use a coffin?” They had a good laugh about that, and went back to work.

STEREOTransportCaseEricBellm

The STEREO boom transport case. Thanks to Eric Bellm for providing the photo.

A few days later, Jeremy returned to Dave’s office, asking if he had been serious about using a coffin. He had researched both options, and learned some interesting facts about caskets along the way.

Caskets can be made from metal, which was a requirement for STEREO, and one could be bought for $6000 and delivered within two days. For comparison, a custom built metal case would’ve cost more than $12,000 and taken 6 weeks to get delivered. Being on a tight schedule, the choice was obvious. A casket was ordered, and the boom shipped to LA in this rather unconventional container.

One additional thing had made using a casket especially attractive – it turned out that every wide-body airplane has a special space for a casket to be transported in the nose of the plane.  So, not only was it cheaper and faster, but shipping was significantly easier since it was a container in a standard form that people were used to dealing with.

This shipment no doubt raised more than a few eyebrows, and one can only imagine what went through the heads of the people dealing with it. Was some old, worn-out instrument getting retired and transported to its final resting place? Do NASA really send dead aliens in caskets? Or had some high-ranking official within the organization passed away? Sadly it was not nearly that interesting, it was merely some astronomers being dead serious about getting their instruments delivered on time.

It’s also a good example that not everything in astronomy needs to be custom-made. Sometimes less will do just fine, even if less means something unconventional.

Thanks to Jeremy McCauley for providing this anecdote.

“Mind your words, young man”

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Astronomical observations are naturally very sensitive to light pollution, which is why you typically place observatories in desolate locations. Even there, you are not guaranteed success, as someone may turn on the light in the dome, shine a flashlight towards the telescope etc. meaning that your observations will be ruined.

Young George Coyne was observing at the Vatican Observatory in Castle Gandolfo, when someone opened the door to the observatory and let in a lot of light, ruining the exposure. George shouted “close that bloody door”, after which the visitor promptly vanished, closing the door behind him. George then continued his observations for the remainder of the night, without further interruptions.

The following day, Pope Paul VI reminded him “my son, you should be in better control of your temper.”

Guess you never know who might be popping by the observatory at night…

Blame the animals, it wasn’t our fault!

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When doing radio interferometry observations, one needs to combine observations from a number of different telescopes, at different locations, to get good quality data. This of course means that there is a potential for a lot of different things going wrong, as one needs to deal with multiple sites. Some of the problems that may come up, are completely out of your hands. However, even if one is having problems with the observations for these reasons, as the good scientists we are, we investigate the problems in detail. This is to make sure that it was indeed out of our hands, and not just us overlooking some obvious step we could have taken to avoid the issue in the first place. A situation that occurs more frequently than one would imagine.  Such inspection can also allow us to at least put the blame for loss of observations in the right place. Whether this means it will not happen again, is a completely different story. A beautiful example of this is the following excerpt from a paper by N. Bartel and colleagues on radio observations of the galaxy M82:

“No data were taken at station D during the period 0830 to 1630 GST due to the presence of a red racer snake (Coluber constrictor) draped across the high-tension wires (33,000 V) serving the station. However, even though this snake, or rather a three-foot section of its remains, was caught in the act of causing an arc between the transmission lines, we do not consider it responsible for the loss of data. Rather we blame the incompetence of a red tailed hawk (Buteo borealis) who had apparently built a defective nest that fell off the top of the nearby transmission tower, casting her nestlings to the ground, along with their entire food reserve consisting of a pack rat, a kangaroo rat, and several snakes, with the exception of the above-mentioned snake who had a somewhat higher density. No comparable loss of data occurred at the other antenna sites.”

At the very least, that snake will not be interrupting the observations again in the future. If you are interested in the actual outcome of the observations, the paper can be read in full here.

Getting your priorities right

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Astronomers tend to be very dedicated to their work, and giving it very high priority in their lives. This is likely true for any branch of science, but sometimes you wonder if we are getting those priorities quite right. Here’s a story from back in the days;

Friedrich Argelander was observing at the observatory of Turku, Finland, on the 4th of September 1827, when a fire broke out and destroyed practically all of the city, including the university. Argelander’s observation log contains the following line:

“Hic observationes terribili illo interceptae sunt incendio, quod totam fere urbeam ad ineres reduxit, observatorium vero, gratiae habeantur Deo O.M., salvum intactumque reliquit.”

Argelanders' observing log on display at Helsinki University. Photo credit: Olli Wilkman.

Argelanders’ observing log on display at Helsinki University. Photo credit: Olli Wilkman.

which roughly translates to:

“Here the observations were interrupted by a terrible fire, which reduced the entire city to ashes. The observatory was, thank God, spared.” A couple of days later the astronomical observations continued as normal. One could argue that most other people would likely have a rather different opinion on what should be considered important during such a disaster.

After the fire the university was moved to Helsinki, where it remains, now called the University of Helsinki.

Getting too attached to your work.

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When observing with telescopes, a fairly fundamental requirement is that the telescope dome is open. This will also mean that whoever is inside the dome, will be exposed to the elements, which may require some special precautions. In particular if you are observing in the colder parts of the world. Like, for instance, Poland.

The winters in Poland can get quite cold indeed. But this will not hold back the dedicated astronomer from braving the elements to get some much needed observing done. This was the case during a particularly cold night at the observatory, where the guiding of the telescope is done manually, by looking through an eyepiece. As astronomical exposures are often rather long, this eager scientist had to guide the telescope during the full 30min exposure he was performing.

Having secured the exposure, the observer no doubt wanted to celebrate this, by getting back inside in the warm, and have a nice, steaming hot cup of coffee (I know I’d want that!). However, when the poor man tried to leave the telescope, he found that this was in fact, impossible to do, without leaving behind a significant amount of skin from around his eye. Anyone who watched “Dumb and Dumber”, can likely imagine the general concept of what had happened…

Luckily for this guy, he had quite some acrobatic skills, and very flexible body parts, so after fiddling around for a while, he managed to unscrew the entire eyepiece and carry it with him inside, resting it on a table for another 15 minutes, before the entire thing had defrosted and could be removed from his eyebrow.

This amount of dedication and attachment to your work is rarely seen and definitely deserves sharing with the world.

Signal lost!

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When doing observations, it sometimes happens that things just won’t collaborate, one way or the other, making it impossible to get any good data. This is true for all areas of astronomy, where you can have clouds, high water vapor, light pollution, radio frequency interference or equipment malfunction of various sorts. Sometimes the reasons for not getting observations are tricky, but in other cases they are fairly obvious… Or so you would think.

Doing a pulsar survey one night at the Parkes Observatory, an undergrad student observer doesn’t seem to be getting any good data from the 64m radio telescope. In fact, he’s not even getting bad data, he’s getting no data at all. As much as it is annoying getting bad data, getting zero data is just immensely frustrating. The bad data would at least get you something that could potentially be useful. But having gone through all the planning and work associated with observations, for zero gain, is just painful.

After long hours that no doubt involved pulling out hairs and being frustrated, the relief, which happens to be the supervisor of the undergrad student, enters the observing tower at 4am. He’d apparently been keeping an eye out for things on the ground on the way there, as he had found a receiver lying on the ground outside. His immediate reaction was along the lines of “Huh, I wonder what that’s doing here? I better pick that up and bring it in with me.” The receiver was then brought to the control room, after which the supervisor continued to try and get some observations going, with very limited success.

At sunrise, one of the staff members arrive, to meet what was no doubt a very frustrated astronomer, who had not gotten any useful data at all that night. Upon seeing the receiver in the control room, he casually pointed out that there was a very nice receiver-shaped hole in the radio dish. In fact, it looked suspiciously like the receiver the supervisor had picked up during the night, would fit exactly there. Which of course provided an immediate explanation as to why no data was received. One can only wonder, why this had not come to mind earlier. I suppose it’s like when you are looking for your glasses while already wearing them. You just don’t see what’s right in front of you.

The Parkes Radio Telescope from the air Credit: Shaun Amy, CSIRO

The Parkes Radio Telescope from the air. Credit: Shaun Amy, CSIRO

Apparently, the receiver had recently been changed, and whoever was putting the receiver in, had not tightened the bolts sufficiently, so as the telescope was turning, the receiver had gotten loose and fallen to the ground. I suppose that the lesson here is: If you find a fairly essential piece of your instrument in a weird place, that might be a good place to start, when trying to figure out why nothing is working. In addition to that, some safety advice; Always wear a hard hat when observing. Even if in the middle of nowhere, with no tall things around, you never know what might hit you.