Tag: Keck

Yeah, It Was One of Those Days

Can anything go smoothly? Please?

A simple job. Get an 80 pound optical interferometer back under the bench. Nothing like two guys setting the thing on my chest so I can worm my way underneath and heave this beast back onto it’s shelf. Then we have to bolt the fold mirror back in place, another thirty pound piece of awkwardness, just hold it in place to get the bolts in. I hold while Olivier tries to thread the bolts. We also have to replace the pellicle, a bit of ultra-thin optical film that will break if you touch it. Then there is an hour spent aligning the thing. chasing my tail trying to get a properly centered image of the deformable mirror. Sometimes optical alignments just go that way. I finally got a decent image, just to learn there was some vibration in the system. I adjusted some shims to reduce the issue, but there is more to be done.

Much of the remaining day is spent troubleshooting a simple optical shutter in the K1 laser. It fails to completely open. When it fails the safety system detects the failure and shuts down the entire laser. A couple hours of checks later has me convinced that the hardware is working, more or less. The design could have been better. The critical issue is the tight timing requirements. The circuit expects the mechanical shutter to actuate in 50ms, it used to, but as it has been used for a few years, it doesn’t any more. Why they did not simply allow a few hundred milliseconds I have no idea, dumb design, there is no issue with a longer timing window.

One of those days
One of those days on the summit in the K1 laser enclosure
Of course I can not simply change the timing. It is hard coded into a Xilinx CPLD. Give me a few days to setup the Xilinx software, another day or two to understand the code, then maybe I could fix it. I have one day, then the laser is scheduled to be on-sky. Great, time to use my hacking skills to dream up a solution in one day… Tomorrow.

There is a camera in the laser enclosure. We use it for tele-presence. As I worked, Pete, our laser engineer, was on the phone assisting from headquarters. He could run the software remotely and watch as I probed the system to measure the timing. Unbeknownst to me, Pete saved a couple images from the camera and sent them to me. The photo does reveal the day I was having. Thanks Pete… I think.

Employment Opportunity at Keck – Adaptive Optics Opto-Mechanical Engineer

Adaptive Optics Opto-Mechanical Engineer

W.M. Keck Observatory seeks a qualified Opto-Mechanical Engineer at its facilities in Hawaii to join a team that develops optimizes and maintains the Observatory’s Adaptive Optics (AO) systems.

Keck Observatory operates two of the largest and most scientifically productive optical/infrared telescopes in the world. Both telescopes are equipped with operational Laser Guide Star (LGS) AO systems whose capabilities continue to be developed to maintain their scientific competitiveness. The twin 10-meter telescopes are located on the summit of Mauna Kea, at almost 14,000 feet above sea level on the Big Island of Hawaii, one of the premier sites for astronomy.

Responsibilities

  • Opto-mechanical design including analysis, tolerancing and error budgets.
  • Implementation and optimization of opto-mechanical systems including installation and alignment.
  • Maintenance of the AO system opto-mechanics including preventative maintenance,
  • Performance monitoring and troubleshooting.
  • Prepare and review written documentation and drawings for new systems and modifications to existing systems.

Qualifications

  • B. S. in Opto-Mechanical, Optics or Mechanical Engineering or equivalent.
  • Experience with Adaptive Optics or instrument development.
  • Track record of precision designs of opto-mechanical components/systems.
  • Competence with Zemax, SolidWorks or equivalent.
  • Engineering process and documentation experience.

Applications/Resumes are received online only via the website:
www.keckobservatory.iapplicants.com

Light Snow Makes for a Pretty Day

A light snowfall delayed our arrival at the summit this morning. It was really only a few inches, but as usual it drifted into all the wrong places. Thus ice and drifts on the road meant we were waiting for the snowplows to break through.

Waiting was no problem, the Sun was out, creating a very pretty mountain. Olivier and I walked up to Keck from below Subaru as the snowplow cleared the last bit of road. We both had cameras in hand, enjoying the scenery. Not a lot of snow, but a fair amount of ice on any exposed surface. A few days before Christmas it all seemed appropriate.

After a quick job in the AO bench we needed to wait for some adhesive to cure. I ended up joining in with the snow shovel crew, clearing our doors and walkways of small drifts. Shoveling snow is not easy at nearly 14,000ft. Breathing hard, but having fun…

Light Snow
A light snowfall atop the summit of Mauna Kea

Comet Lovejoy in the Daylight

I did attempt to see comet C/2011 W3 Lovejoy in the daylight. I actually tried several times. Once on the morning of the 15th and a couple more times on the morning of the 16th after I heard that the comet had survived perihelion passage. Neither time did I see the comet with an unaided eye.

On the 15th I was not surprised I could not see it. I was in Waimea where there was a lot of low altitude haze and a lot of glare around the Sun. On the 16th I had a much better chance using the clean high altitude air of the summit of Mauna Kea. But still, no comet seen even though it should be just over four degrees from the Sun. This is about the same separation that had allowed me to see comet McNaught in early 2007.

Just to be certain I set the camera on a tripod, placed it just inside the shadow of the Keck 1 dome, and blazed away. Examining the photos on the camera display likewise revealed no trace of the comet, but there were some interesting spots of light.

It was not until I sat down and really analyzed the raw frames that I found something. Using some astronomy software, I calculated the position of the comet when the shots were taken and the field of view of the camera. And lo! There it was, a small spot with a trace of tail. It showed up best in the green channel, and not at all in the blue thanks to Rayleigh scattering in our atmosphere. Stacking nine of ten frames and processing the heck out of the frames does allow you to clearly see the comet…

Comet C/2011 W3 Lovejoy
Comet C/2011 W3 Lovejoy photographed 4° from the Sun on at 19:47UT on the morning of 16Dec2011. Canon 60D and an 85mm lens, stack of nine frames, green channel only.

Postcard from the Summit – Colorful Commute

As winter descends on Mauna Kea, commuting to and from the summit had become… interesting. Fog, snow and ice being regular features of the drive. Winter weather has also brought fantastic cloud formations, all the more interesting as you drive into them. The later dawn and earlier sunset means that our usual arrival and departure times are filled with dramatic light. All elements become part of a spectacular show.

Colorful Commute
Shane, a Mauna Kea Ranger, heading down the mountain into a rainbow

Article in the North Hawaii News

CB52-80-07286-DCLarry, our PIO officer asked me to write an article about Keck for the North Hawai’i News. He has arranged for us to get a nice one page article into this local weekly paper each month. This month I contributed the text and photos for the Nov 10th edition.

It is interesting to write a piece for a more traditional format. With the added advantage of having a professional do the editing, with feedback. The result is much like the articles I have written for Darker View. Some rehashing of material I have used here, but re-written to provide a more complete story. The photo below is the one chosen by the editor to illustrate the article.

Pushing Steel

A snippet of overheard conversation. I was in Keck 2 control talking with the operator when a few words drifted over the video conference link from Keck 1. Some sort of trouble. I headed for the other end of the building.

Sniffen, our night attendant was looking for the cause of a drive fault. For some reason the computer refused to move the telescope, displaying a drive fault error. It would not move manually either, drive power would not come on. As he explained this to me I was a bit worried. This could be really simple, or really bad. Possibly something that would cost us the night.

Fisheye Keck 1
The Keck 1 Telescope awaiting lights out and release for the night
Opening the doors to the drive electronics cabinet I began decoding the cryptic status and error LED’s on the interlock control boards. Dozens of unlabeled indicators with a chart pasted to the door, a bit of 1980’s tech we still have to deal with, upgrade scheduled for the year after next. It takes a few moments… Right Final Limit error?

Sniffen and I looked at each other… How had the computer driven into a limit? This was not supposed to be possible. While we occasionally put the scope in a limit during maintenance, I had never heard of this occurring during the night. Was it really in the limit? The computer was indicating we were well clear of the limit. Something was lying to us.

Walking out into the dome and looking up confirmed we actually were on the limit switch. The telescope had driven as far around in azimuth as it could go, stopping just before the hard stop, a massive steel assembly that will definitely stop the telescope.

Oh !#%$! We have to push.

Yes, it is possible to push 300 tons of steel when it is floating on a film of oil. I have never had a chance to do it myself, but years ago someone had shown me how to do it. With Sniffen pressing a pair of pencils into the electrical contactors to release the brakes, I shoved the telescope out of the limit.

It moves surprisingly easy. I had braced my back against the laser enclosure and put my feet against the steel rails used to move the instruments. One good shove and it was moving. I really did not need to brace so well, just a good hard lean against the railings would have done it.

Once you get 300 tons of steel moving, it keeps moving. After I stopped pushing it continued to glide for another few degrees. Low friction creating a clear example of Newton’s first law of motion.

A surreal experience… 2am, in a darkened dome with stars overhead, pushing one of the world’s largest telescopes by hand. Life is interesting sometimes! Twenty six minutes of precious dark lost, but with a quick reinitialization of the telescope we were back on-sky.

Postcard from the Summit – Laser Panorama

Assembling panoramas properly is not a trivial exercise. I have been attempting to master a program called Hugin and may have achieved some modest level of competency with it. It is surprising complex, and extraordinary powerful. Even more impressive as it is free software. Properly mastered it allows correction of tip, tilt and yaw in the camera, lens distortion, even translation of the camera’s position in x,y, and z. The task is made even more complex if the scene changes during the sequence, which is inevitable during the fifteen minutes it takes to sweep a moonlit scene on the observatory roof with one minute exposures. The stars move, the telescopes move, while I try not to shiver uncontrollably in the bitter wind.

Laser Panorama
A moonlit panorama from the roof of Keck during a night of laser engineering

Keck and a Nobel Prize

We are celebrating a bit at Keck today. It is somewhat unusual for an astronomer to be awarded the Nobel Prize in Physics. Today it was announced that three astronomers will share the award for their work in cosmology. Saul Perlmutter, Brian Schmidt, and Adam Riess led a pair of teams that were investigating the expansion of the universe through observing type Ia supernovae. Saul Perlmutter led the Supernova Cosmology Project, while Brian Schmidt and Adam Riess led a separate group, the High-Z Supernova Search, performing nearly identical work.

Both teams discovered something disturbing in the data. The expansion of our universe appeared not to be slowing as astronomers expected, but actually accelerating. The result, had both teams scrambling to understand the data, checking and triple checking everything in an attempt to see where they had gone wrong in their analysis. When each team finally published they were glad to see that they were not alone, that another group had independently confirmed this unexpected discovery.

A couple decades later we have come to accept this result as further data has accumulated. We now understand that there is another element of the universe that had not been appreciated before. What the astronomers had found was the effects of something that had been hinted at in a number of physicists theories (including Einstein), something we now call Dark Energy.

SN2011fe in M101
Type Ia supernova, SN2011fe, in the galaxy M101
The teams used a number of different telescopes in a coordinated effort to both discover and then obtian the spectral data on the supernovae. Smaller telescopes would be used to discover the supernovae, searching wide swaths of sky looking for these rare events. Then the team would use large telescopes, like Keck, to gather the spectral data of the supernovae. The spectra would confirm the event as a type Ia supernova and give the redshift.

The most critical data, the spectra of the furthest and faintest supernovae, were made possible by the Keck telescopes, then the largest in the world. It is these most distant objects where the effect of our universe’s accelerated expansion is most noticeable. Looking through the tables of data in the original scientific papers, the Keck Observatory is often credited.

It is somewhat unfortunate that only a few individuals are named with a Nobel Prize. The discovery of dark energy and the acceleration of the expansion was an effort made by teams of individuals. Both supernovae search teams and all the members deserve real recognition for this. In turn their efforts depended on the staffs of the observatories that made the observations possible. Big discoveries are rarely made by individual scientists, but by the cooperative effort of many. There are only three names on the Nobel Prize, but a lot of folks are celebrating today.