Postcard from the Reef – Raccoon Butterflyfish
TMT Construction Restarts
With the announcement the TMT will restart construction everything seems headed for a showdown on the mountain. The protesters are clearly preparing for action. The day is Wednesday. I was scheduled to do a training session for our crew this Wednesday, I have cancelled this. This sort of thing is common as the rest of the observatories consider how we will deal with a possible prolonged blockage of the road.
Dan confirms that the rocks were rounded boulders in mixed sizes. Rounded rock, as one would find in a stream bed, is particularly desirable in the building of a proper sacred structure such as an ahu or heiau. According to legend that the rock to build the great heiau at Puʻu Kohala was hauled all the way from Waipio Valley by a chain of men across the island.
Obviously they are daring the construction crews to dismantle the structure, then to be able to claim desecration when that happens. Whatever happens our crews will have a first hand view from our site overlooking the TMT site.
I hope for more updates as the situation evolves. With Wednesday cancelled I still hope to go up Friday to complete a few things, whether I do attempt to go up is a bit indeterminate at the moment. Will wait and see.
Venus and Jupiter
The dance of Jupiter and Venus continues in the evening sky. Over the next few days we will see the pair drawing closer. Currently an obvious pairing in the sky after sunset, the two are just 4.5° apart today. With Venus shining at -4.4 and Jupiter somewhat dimmer at magnitude -1.8 it is hard to miss the pair.
The closest approach will be about 0.3° on June 30th at 16:14HST. Thus the evening of June 30th will see the pair at their closest for observer in Hawaiʻi. If you want to see the closest approach you can also try to observe the conjunction in the late afternoon sky. Both planets are bright enough to see in the daytime.
After this the pair will separate slowly and disappear into the sunset glow together.
At their closest the two will be easily close enough to bee seen together in the low power view of amateur telescopes. It makes a fascinating sight to see the two planets together in the eyepiece.
Summer Solstice
Summer solstice occurs today at 06:38HST. Today the Sun will occupy the most northerly position in the sky of the year. The term solstice comes from the latin terms Sol (the Sun) and sistere (to stand still). On this day the Sun seems to stand still as it stops moving northwards each day and begins move to the south. This is the first day of summer as marked by many cultures in the northern hemisphere. Alternately this is the first day of winter for those living south of the equator.
| 2015 Solstices and Equinoxes | ||||
|---|---|---|---|---|
| UT | HST | |||
| Perihelion | Jan 4 | 08:59UT | Jan 3 | 22:59HST |
| Vernal Equinox | Mar 20 | 22:45UT | Mar 20 | 12:45HST |
| Summer Solstice | Jun 21 | 16:38UT | Jun 21 | 06:38HST |
| Apehelion | Jul 6 | 12:59UT | Jul 6 | 02:59HST |
| Autumnal Equinox | Sep 23 | 08:20UT | Sep 22 | 22:20HST |
| Winter Solstice | Dec 22 | 04:48UT | Dec 21 | 18:48HST |
| Source: NASA Sky Calendar | ||||
Fabrication
Scientists Discover Brightest Early Galaxy and Likely First Generation Stars
W. M Keck Observatory press release…
Astronomers using several of the largest telescopes on Earth and space have discovered the brightest galaxy yet found in the early Universe and have strong evidence that examples of the first generation of stars lurk within it. The results have been accepted for publication in The Astrophysical Journal.
A team — led by David Sobral from the Institute of Astrophysics and Space Sciences, the Faculty of Sciences of the University of Lisbon in Portugal, and Leiden Observatory in the Netherlands — peered back into the ancient Universe, to the reionization period approximately 800 million years after the Big Bang. Instead of conducting a narrow and deep study of a small area of the sky, the team broadened their scope to produce the widest survey of very distant galaxies ever attempted.
Continue reading “Scientists Discover Brightest Early Galaxy and Likely First Generation Stars”
Dome Control PLC Replacement
The time came.
It moved.
700 tons of steel and aluminum smoothly rotated until I hit the stop button.
Nothing crashed or seriously broken.
It even moved the right direction.
The risk of breaking something was a real possibility. A mistake here could leave the dome damaged for days or weeks and the telescope useless. I reviewed my plan one more time before starting. A fully written plan with a step by step testing method carefully thought out and reviewed by the other engineers in the department. The plan also had a whole section of “what can go wrong” risk analysis, with risk mitigation steps. What if the brakes release but the motors do not come on? What if the old controller fails when removed from the system?
After a fitful night’s sleep and a long ride to the summit the moment came when I brought the new controller online. Swapping out the connections with the old controller and applying power, the correct indicator lights came on. Even better, as I tested each of the controls in turn the dome and shutters operated perfectly. It worked from the control panel, from the radio controller, under computer mode from the control room. I even tracked the telescope and dome together for an hour without trouble. The tracking was excellent, within 0.1° the whole time.
New Moon
Keck Domes
Serious Apprehension
Today is the day I will close my eyes, cross my fingers, and press a button.
Further tests will open and close the shutters. If anything this part is even more worrisome. The controller is responsible for releasing the brakes on the shutters. If the brakes were to open without motor power the shutters will be able to simply run downwards.
Fortunately they will not fall, but they can run downwards to the hard stops rather quickly. There will be a tech stationed at the shutters with a finger poised over the e-stop button during these first tests. The button blows the dome main breaker, which removes power from the brakes, causing them to close.
A brain replacement is fraught with opportunities for error. Currently the old and new PLC’s sit next to each other in the cabinet, installed last week. Monday morning I will remove the old one and slave the I/O cards to the new controller.
Then the testing begins.