I first saw it from the highway as we approached Honokohau, the sailboat in a bad spot.
A very bad spot.
A large vessel is sitting on the reef just off of the Honokohau beach about half a mile north of the harbor entrance. The beach is closed as it is part of the Kaloko-Honokōhau National Historical Park, closed along with other effects of the federal shutdown. We took a few photos as we cruised past the beach on the way to a Sunday morning of diving.
I looked through the news Monday, looking for information on the incident. There is none, no explanations as to how the sailboat got onto the reef, or what is being done about it. Everyone in the harbor knew about the boat, not a whisper in the media. Tuesday’s news?
A very nice day. True, the weather was not great, scattered clouds and vog in Kona. It was a great day to be underwater. We dove Pipe Dreams and Hoover’s Tower, for a pair of pleasant dives on a Sunday.
Pete was playing with a new toy, a very nice Fix housing for his G12 with a wide angle dome. The results are some very nice photos…
The author diving the intake pipes at OTEC, photo by Pete Tucker
An evening stop in the local market to pick up a few groceries. There is always a stack of local newspapers on the checkout counter. But this edition looked a little familiar… That is my photo! I knew Steve, our PIO at Keck, had forwarded the image to the newspaper. I did not expect it to be at the top of the front page!
The image has gotten some traffic. Posted to Facebook the news of snow on Mauna Kea resulted in the highest traffic day I have had in years for this blog. It is not even a great image, just a snapshot taken as we headed for the vehicles to get off the mountain. The light is horrible, the scene seems flat, but it is snow, and that is always big news around here.
Actually, this is my second front page image. A panorama shot from the Keck roof was featured on the front page of the Star-Advertiser earlier this year. It is always a nice surprise to see an image of mine get some press!
The front page of the West Hawaii Today, 12 Oct 2013
Photography was not always a process of pixels, megabytes, SD cards and Photoshop. Once it was chemicals, paper, darkrooms and something called film. I learned to shoot in another age, when every shot counted, there were only 24 or 36 frames available. When it was a week or at least a few days before you knew if the shot worked.
The stream flowing into marble Grotto makes a tempting target for a medium format film camera, photo by Randy ZelickI still have a few relics of those days, cameras kept for the memories they carry. Traveling through Europe or the Desert Southwest, capturing images on celluloid and silver. Several experiences over the last couple months have served to remind me of those days… Walking into a camera store in Portland, a store that is as much a museum to the era of film, shelves filled with beautiful machines from the past. Watching Randy load roll film into a classic Pentax 6×7 on a glacier in Alaska, hearing the soft click of that mechanical masterpiece. Reading blog posts from a friend on Oahu about his adventures in film.
Winter might just be starting in Hawai’i. A fall storm dropped the season’s first snow on the summit of Mauna Kea this afternoon. Not much, just enough to turn the summit white. I had to scrape the frozen snow from the windshield to free the wipers before I could drive down.
We got 1.2″ of rain at the house, quite a bit when you consider we get 10″ a year in the shadow of the mountain. I am headed back to the summit tomorrow morning, wondering what we will find, this storm is just starting.
A light snowfall marks the start of winter on Mauna Kea.
Warping is not much fun. Warping is now on my list of responsibilities. At least I know I am accomplishing something critical to the operation of the telescope.
A Keck mirror segment after stripping and cleaning, ready to place in the chamber to receive a new reflective coatingWarping is a process of tuning the performance of a mirror segment after a segment exchange. A segmented mirror offers large advantages over a monolithic mirror, not least of which is the ability to swap a few segments out for re-coating and refurbishment without the weeks of downtime needed to re-coat a monolithic mirror. Throughout the summer Keck schedules a couple days of SegEx each month, so that at the end of the summer we have a completely clean and re-coated mirror.
Exchanging segments does require some interesting procedures to realign each new segment, each must be warped and the edge sensors tuned. The first few hours of the night after a SegEx is used to evaluate the performance of the newly replaced segments. Using a special alignment camera system the optical figure of each segment can be evaluated and a set of corrections generated to be applied the next day… Warping.
A map of the segment types in the Keck primary mirrorThere are six segment types that make up the primary mirror, each with the slightly different curve needed to make up the correct part of the hyperbolic curve. In theory the segments are interchangeable, any type four can be swapped with any other type four. This works… With a little help. It is necessary to adjust the figure of each segment, just slightly, to tune the figure of each segment for its place in the array.
To apply the correct pressure there are small knobs and screws at specific points in the whiffle tree. Each adjustment point also contains a strain gauge, allowing the applied pressure to be measured precisely. A computer and analog interface allows all of the points to be read out and checked against the calculated values.
the warping computer set up in the subcellThere are thirty adjusters and strain gauges on the back of each mirror segment. The problem is that you can not simply adjust each one. Adjustment of one point affects all of the nearby points, particularly if the adjustment is large. Typically it is necessary to go around three times before the segment is properly warped. Thirty adjustments becomes ninety. Three segments in a day becomes 270 knobs to turn, 540 over two days, a lot of knobs.
After setup, it takes about an hour to do each segment, an hour of painstaking frustration. the mirror cell is just the right height, too high to sit down and reach the knobs, too low to stand up fully. Working in a jungle gym of frigid steel just makes it worse. A day in the mirror cell is a nice recipe for a tired and sore body.
How careful was I? Did I get all of the points set correctly? The computer is displaying all of the correct numbers. I will not know until the next day, when the night’s performance data is reduced, when we can see the figure of the primary mirror and check the errors.
My first warp is a success, most of the segments show less than 20nm rms error. Next SegEx there are only two segments being exchanged, but Sergey is threatening to have two others re-warped to address some lingering issues. Four? Better than six. Only 360 adjustments to make, more or less.
Today Mercury reaches maximum elongation, the furthest point it will reach from the Sun in our sky and the highest it will be above the sunset for this evening apparition. The planet is easily visible as a bright, starlike object about 25° above the setting Sun as twilight begins. Over the next couple weeks Mercury will slide back into the sunset, heading for inferior conjunction on November 1st.
