Tag: Keck

Shaken and Back On-Sky

I understand it was quite the scramble, but both telescopes are back on-sky tonight.

The earthquakes started just after two this afternoon with the magnitude 4.5 event that got our attention so quickly. This gave day crew three hours to have everything inspected, checked out and ready for the night. Physical inspections, instrument checkouts, and more, an extensive checklist to follow and insure that no real damage was done by the temblors. Just after 5pm we got word that everything was good-to-go and both telescopes would be released for the night’s observing.

As of writing this, about ten hours after the first quake, there have been 32 separate events under Mauna Kea detected by the seismographs. A half dozen of those were near magnitude three. I have felt thirteen separate aftershocks, this plus the original quake makes fourteen, the most I have ever felt in a single day by a wide margin.

The USGS has released a statement noting that this was probably a “structural adjustment” a result of the enormous weight of Mauna Kea stressing the underlying rock…

Magnitude 4.5 earthquake on the north flank of Mauna Kea

By USGS/HVO

Hawai‘i Island, HAWAII—The U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO) recorded a magnitude-4.5 earthquake located beneath the Island of Hawai‘i on Wednesday, October 19, at 2:10 p.m. HST. This earthquake was centered about 9 km (6 mi) northwest of Mauna Kea’s summit and 49 km (31 mi) west-northwest of Hilo, at a depth of 18.7 km (11.6 mi).

The earthquake was widely felt on the Island of Hawai’i. The USGS “Did you feel it?” Web site (http://earthquake.usgs.gov/eqcenter/dyfi/) received more than 500 felt reports within an hour of the earthquake.

The earthquake was the largest in a cluster of about 20 earthquakes on the north flank of Mauna Kea on Wednesday afternoon. Most of these aftershocks were too small to be felt, but, as of 3:30 p.m., two earthquakes with magnitudes greater than 3.0 had occurred in addition to the magnitude-4.5 event.

Over the past 25 years, the north flank of Mauna Kea has experienced 10 earthquakes greater than magnitude 4.0, including today’s event, at depths of 10–40 km (6–25 mi). Deep earthquakes in this region are most likely caused by structural adjustments within the Earth’s crust due to the heavy load of Mauna Kea.

Adjustments beneath Mauna Kea during past similar events, such as in March 2010, have produced a flurry of earthquakes, with many small aftershocks occurring for days after the main quake. Given this history, it is possible that additional small earthquakes may be recorded in the coming days.

Today’s earthquakes caused no detectable changes on the continuing eruption of Kilauea Volcano.

For eruption updates and information on recent earthquakes in Hawai’i, visit the Hawaiian Volcano Observatory website at http://hvo.wr.usgs.gov

Nobel Prize in Physics Awarded for Accelerating Expansion of the Universe

W.M. Keck Press Release…

The expansion of the universe is accelerating, and this is likely driven by dark energy, a mysterious repulsive force. Three astronomers won the Nobel prize on Tuesday for their research on exploding stars, or supernovae, that led to this profound cosmological conclusion. They are Saul Perlmutter of the Lawrence Berkeley National Laboratory in Berkeley, California, Brian P. Schmidt of the Australian National University in Weston Creek, Australia, and Adam G. Riess of the Space Telescope Science Institute and Johns Hopkins University in Baltimore, Maryland. Their discovery relied fundamentally on spectroscopy using the W. M. Keck Observatory and its LRIS spectrograph, in the period 1995 to 1997.

Perlmutter, Schmidt and Riess were members of two competing teams who were both studying the most distant supernovae. These Type Ia supernovae have been demonstrated to be “standard candles” and can thus yield relatively precise cosmological distances. The Keck spectra of the extremely distant supernova candidates were essential in order to indicate they are Type Ia, and to determine the redshift, or its velocity as seen from Earth, of the galaxy hosting the supernova. It was the redshifts and distances of a modest number of distant supernovae that revealed that the expansion of the universe was not slowing down, as was predicted, but in fact was inexplicably speeding up. The accelerating expansion of the Universe, first reported in 1998, was confirmed by the two separate groups. This accelerating cosmological expansion and the hypothesis that it is driven by dark energy has now become one of the most important areas of study in astronomy and physics today.

At the time, “We were a little scared,” Schmidt said. Subsequent cosmological measurements have confirmed that roughly 70 percent of the universe by mass or energy consists of this anti-gravitational force called dark energy.

In fact, Albert Einstein introduced this bizarre behavior with a fudge factor in his equations in 1917 to stabilize the universe against collapse. He later abandoned this idea, and then considered it his greatest blunder. “Every test we have made has come out perfectly in line with Einstein’s original cosmological constant in 1917,” Schmidt said.

In the years since then the three astronomers, along with their collaborators, have shared a number of awards, including the Shaw Prize in Astronomy, for this ground breaking research.

Perlmutter, who led the Supernova Cosmology Project out of Berkeley, will get half of the prize of 10 million Swedish kronor ($1.4 million). The other half will be shared between Dr. Schmidt, leader of the rival High-Z Supernova Search Team, and Riess, who was the lead author of the 1998 paper in The Astronomical Journal, in which the dark energy result was first published. They will receive their prizes in Stockholm on December 10.

“The recognition by the Nobel Committee of the importance of this work validates the enormous value to our society of ground-based optical / infrared astronomy,” said Taft Armandroff, Director of the W. M. Keck Observatory. “By making our two Keck telescopes and their instruments work at the highest performance, transformational science like that of Saul Perlmutter, Brian Schmidt and Adam Riess happens.”

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system. The Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

Laser Susan

The old saying “Necessity is the mother of invention” has a certain truth to it.

In this case the necessity is created by the conditions. Sub-freezing temperatures, bone chilling wind, and the need to be outside under these conditions. The summit of Mauna Kea can be downright miserable for mere human beings. Yet, in order to operate the laser, someone has to watch and insure we do not illuminate some passenger aircraft on the way to Australia.

Thus we have laser spotters, a hardy crew indeed. Braving the conditions, spending hours watching the sky to insure we operate safely. We are attempting to introduce technological solutions to the problem. The FAA however is an extraordinarily conservative organization, rightly so when hundreds of lives are at risk on any given flight. It takes time, many years, to approve another method of insuring safe laser operation.

It is a cold job. I have done it for a few hours, just enough to instill a real respect for the guys who do it all night. You bundle up in many layers of insulation and attempt to get comfortable in a position that allows observation of the area of sky around the beam. Given the heavy clothing it is a pain to simply sweep the sky, and completely reposition each time the telescope changes target.

Given the problem, Doug Macilroy, one of our intrepid Keck crew, saw a solution. It took time, and a number of prototypes to get it right. But he now has a neat way to stay comfortable and warm while scanning the sky. Now we have the “Laser Susan”!

YouTube video for the Laser Susan

Neptune and Triton

Mike Brown did more than give a lecture while in Hawai’i. He just finished a four day observing run using Keck 2 with AO and OSIRIS, as well as gathering data with NIRSPEC. The target? Among other things Mike and his team observed Neptune and the large moon Triton. Triton is thought to be a captured KBO (Kuiper Belt Object). These objects, including well known Pluto, and lesser known, but just as large objects like Eris, Haumea, Makemake and Quaoar, are Mike’s area of expertise.

It is always nice to see a system I help maintain operating well and producing images like this…

Triton and Neptune
A Keck AO / OSIRIS photo of Neptune and the large moon Triton, credit Mike Brown/CalTech

It’s Fixed

A long frustrating day.

With four days of observing scheduled starting tonight, the pressure was on. Both Keck telescopes, four nights, lost for something I am responsible for? Not an attractive prospect. Everyone in the department has a helpful hint or two, some of them even made sense, most we had already tried. Phone calls and emails fly as everyone chimes in, even the guys at JPL who built the cameras get involved.

It was not until three in the afternoon that I found it. Comparing oscilloscope traces between the two FATCAT instruments I note something amiss in the video signal. Most of the waveforms makes sense, even look OK if viewed alone. The colored trace on the screen isn’t the same as the working camera. Now I recall a couple other waveforms I had looked at earlier and wondered about, even to the point of making some notes about. Realization dawned with an enormous sense of relief. Those clock edges are not supposed to be rounded like that!

I pull the clock driver board out of the working camera and install it in the problem child… The noise goes away!

I stole a spare clock drive card from the instrument guys, from the spares for LRIS. I suppose I will hear about raiding their precious stash Monday when they find my note.

I need both cameras and two good clock boards. The spare has to be configured correctly, which takes another hour of logic and good guesses in the absence of decent documentation. Only two hours before dark we perform the final checkouts on the system, the mood notably lighter as we realize it is going to work.

As I write this the FATCAT cameras are on-sky, detecting fringes of interfering light from some distant star.

An Interesting Day

Any day that starts with two flat tires is bound to be an interesting day.

Waiting for a Spare
Waiting for another spare tire to fix the second flat on Mauna Kea
Yes, not one, but two flat tires in a matter on moments. I felt the first tire blow out and as we inspected the damage a hissing could be heard from the opposite side. The summit road is known to be a problem, and flat tires are not an uncommon event. We do get practice changing tires on this road. Fortunately other Keck vehicles were coming up behind us, and we could ask for another spare to be brought down from the summit. In the meantime we spent a pleasant half hour waiting for the second spare. The weather was beautiful, and so was the view from high on the side of Mauna Kea.

I had planned on working on one of the cameras in Interferometry. The camera has been having trouble automatically filling with liquid nitrogen. In addition I had a list of smaller issues that needed to be dealt with. Unfortunately one of those minor issues turned out to be not so minor.

Fast Delay Lines
The Keck-Keck Interferometer fast delay lines
Thus I spent much of the day troubleshooting Fast Delay Line #5. Used to compensate the optical path between the two telescopes, the delay line is a cart that runs on rails, carrying a set of mirrors. The cart should track very smoothly, changing the path length on the order of micrometers (a few ten thousandths of an inch), instead it visibly jittered and jumped along the rail, something wrong in the motor control software or circuitry. It took much of the day, but in the end it was tracking smoothly.

The entire day was busy from beginning to end. I attempted to finish the last few tasks on my list as the last few minutes of the day sped away. The rest of the guys were ready to leave about a quarter to five, while I was still connecting a few last metrology cables. “Yes, I am coming!” I answered on the radio for the second time. I grabbed my tool bag and headed to the door as the clock hit 17:00.

One of those days I return home exhausted. I will have to head up again, quite soon, to deal with other problems still unfinished. Hopefully a somewhat less complicated day.

Just a Little Nudge

One of the tasks I have helped with on the K1 AO Laser is aligning the Launch Telescope Assembly (LTA). This is not so much an electrical engineer’s task, but a mechanical one. So how did I end up with the task? Simple, I was present the first time it was done. Since the mechanical engineer who was first responsible has now left the observatory, I get the job by default. Just the way things work around here.

The launch telescope is a small telescope, about 0.5 meter in aperture, that projects the laser into the sky. Mounted behind the secondary mirror of the Keck 1 telescope, it must be precisely aimed to exactly the same spot in the sky the main telescope is aimed.

Launch Telescope Adjustments
Adjusting the mounting of the K1 Launch Telescope
The procedure is not all that difficult. Mount two dial indicators in place, restrain the motion by using wooden wedges or a really big c-clamp, loosen the bolts, make the adjustment, tighten the bolts. No problem, right? The challenge is to move the large assembly just a few thousandths of an inch and have it stay exactly where you want it while re-tightening the bolts.

In practice this adjustment is about one to two hours crouched in the secondary assembly of the Keck 1 telescope. Each time the bolts are tightened the assembly moves about 10-15 thousandths of an inch. Thus I have to guess how much to offset the measurement so it ends up correct when the bolts are tight. It takes anywhere from three to five repetitions to get right sometimes.

This is where I curse the mechanical engineer who dreamed up the mounting for the launch telescope. I look at the dial indicators, shift my stance against the cold steel to stop the cramping, loosen the bolts and try again.

The last adjustment was a mere 0.004″ (four one-thousandths of an inch) to move the pointing about 30 arc-seconds on the sky. I am now only about 10 arc-seconds from the optical axis. Keep in mind that a single arc-second is 1/60th of an arc-minute, which is in turn 1/60th of a degree. Ten arc-seconds is pretty good, but we want closer. Here I go one more time…

Postcard from the Summit – In The Hall

Another processed infrared image from Mark Devenot. This time the subject is an everyday scene inside the facility with some of the crew standing in the hallway. The odd feature behind them is actually the large doors that lead into the Keck 1 Telescope dome. Everything looks much different in the thermal infrared…

IR Hallway
In the hallway, a mid wave infrared image taken with a FLIR PM250 camera, with artist effects added in Photoshop, photo by Mark Devenot