Category: Astronomy

Exploring the cosmos

Transit of Mercury May 9, 2016

On May 9th, 2016 Mercury will transit the Sun. While transits of Mercury are not rare, they are not all that common either. The last transit was almost a decade ago in November of 2006. On average there are fourteen transits of Mercury each century or one every seven years. If you wish to observe one the situation is much better than transits of Venus which occur in pairs over a century apart.

This particular transit will favor observers in Europe and North America where the entire transit will be visible. Unfortunately for observers in the islands only the final three hours of the transit will be visible having begun well before local dawn. Sunrise will occur around 05:48 for the island of Hawaiʻi, with the transit ending at 08:42 in the morning.

Mercury Transit
Mercury transiting the face of the Sun, 6 Nov 2006
Mercury Transit May 9th, 2016
  UT (geo) HST HST (offset)
First Contact 11:12 01:12 –:–:–
Second Contact 11:15 01:15 –:–:–
Greatest 14:57 04:57 –:–:–
Third Contact 18:39 08:39 08:39:58
Fourth Contact 18:42 08:42 08:43:10
 

Source: NASA Eclipse website

 
The table at the right gives the transit geocentric UT and offset HST times. As our line of sight is shifted slightly from Hawaii there is a slight offset in the timing from our vantage point.

First contact is simply the first moment that the disk of Mercury begins to impinge on the disk of the Sun. Second contact will be the moment when Mercury is entirely in front of the Sun. Third and fourth contacts are a reverse of first and second with fourth contact as the end of the event.

Observing a planetary transit of the Sun requires proper eye protection. If you can not look safely, do not look! The Sun can cause permanent eye damage if viewed without proper protection. As Mercury is quite small some magnification will be useful in observing this event, a telescope of binoculars with a solar filter. A pinhole camera can be made out of things lying around in your kitchen that provides a very good image. Read my Guide to Safe Solar Viewing for a lot more information on viewing the Sun safely.

The next transit of Mercury will occur November 11, 2019 at 15:20UT (mid-transit). This next transit also favors Europe and eastern North America where the entire transit will be visible.

Mercury Appears in the Evening Sky

The planet Mercury is starting an evening apparition. The planet should become visible this week just above the fading glow of the setting Sun as a magnitude -1 object. The planet is moving about 1° further from the Sun and higher in the sunset each day, reaching a maximum elongation of 21° on May 6th.

Continue reading “Mercury Appears in the Evening Sky”

A Pop, a Puff of Smoke, and an Ominous Red Glow… Not Good

When powering up a nearly three decade old computer for the first time I should really have a video camera running…

The loud pop, and the stream of smoke issuing from the side vents was bad enough. It was the ominous orange glow seen for just a couple seconds from the same vent that really sent me the message…

Not good.

Compaq Portable III
A Compaq Portable III personal computer, circa 1987, photo courtesy Wikimedia Commons
I yanked the power cord as quickly as I could, then just sat there for a moment considering the implications of disaster. A Compaq Portable III, a design first marketed in 1987. A computer that runs DOS, predating the first versions of windows. This is the computer that holds the software that operates the Keck II dome.

Without this machine it will be very difficult to program the old PLC the dome runs on. I do have a replacement for that PLC controller running in my office, but I face the challenge of verifying the design, I would like to run the old software in the test setup to compare it to the new. I would also like to have a backup in case something goes wrong during the transition, a way of putting the old PLC back into the system and programming it.

Continue reading “A Pop, a Puff of Smoke, and an Ominous Red Glow… Not Good”

Reasons to Carry a Camera

I work at the summit of a nearly 14,000ft mountain that sits atop a pretty tropical island. That alone is good enough reason to carry a camera at all times. You never know when you will need that camera, beauty appears when you least expect it.

Dome Motor Controller
The control wiring for a Keck 1 dome VFD motor controller
There are other reasons to carry a camera in my life. I often use the camera to document my work. There is a camera, the little EOS-M, in my backpack alongside the rest of my tools. Wire cutters, screwdrivers, allen wrenches, a multimeter, all the useful tools I need every day, along with a camera, memory cards and spare batteries.

The advent of digital cameras where the cost of each photo is negligible has made this possible. This would not have been practical in the days of film. Yes, I remember those days, counting out every frame of a 36 exposure roll, deciding if the shot was worth it. In this digital age I usually have a dedicated camera along and never worry about shooting. If that camera is out of reach there is always the iPhone in my pocket.

The equipment I work on is often unique, there may be only one copy in the world. Two if we have one installed on both Keck 1 and Keck 2. The documentation can be of varying quality, some is good, some is abysmal, some is just plain wrong. Some of this gear was professionally built by engineers, some of it was built by graduate students who would never need to fix it years later.

Continue reading “Reasons to Carry a Camera”

A Very Short Eclipse

We have been lucky in the islands lately when it comes to total lunar eclipses. A series of total eclipses have been visible from start to end from our vantage point in the middle of the Pacific. There is an average of one eclipse visible per year from any given place, but that is an average, you can go several years without an opportunity. Both 2012 and 2014 have given us two good eclipses and 2015 provides one.

Total Lunar Eclipse 4Apr2015
The sum of 699 exposures taken through the lunar eclipse of Apr 4, 2015
This eclipse would be a bit different however… Overall the eclipse lasted as long as is normal for a lunar eclipse, about three and a half hours. It was the total phase that was unusually short for this particular eclipse. It was only about four minutes that the moon would be entirely within the umbra, the darkest part of the Earth’s shadow. This usually lasts about an hour. The umbral magnitude of this eclipse was 1.0008, just barely over the threshold of one that designates a total lunar eclipse.

On Friday I did a quick interview with a reporter from the West Hawaii, Today, our local newspaper. He was looking for a little more information on the eclipse and a somewhat more local angle than a wire article on this eclipse. I chatted for a while, and got written up in the article…

Continue reading “A Very Short Eclipse”

Mauna Kea Starscape

With all of the emotion being expressed over telescopes on the mountain this week, just a reminder of why Mauna Kea is the perfect place from which to look to the heavens…

Mauna Loa and Meteor
Looking over a snow covered Puʻu Hau Kea to Mauna Loa, a bright meteor is visible, as is the GMD laser, Canon 6D and Samyang 14mm f/2.8 lens, 30s at ISO6400

Total Lunar Eclipse Reminder

Total Lunar Eclipse 14Apr2014
The total lunar eclipse on Apr 14, 2014, Canon 6D on 90mm f/12 APO
Early tomorrow morning a total lunar eclipse will be visible across the Pacific. Sky watchers in Hawaiʻi will be able to observe this event from beginning to end.

Penumbral Eclipse Begins  11:01 HST   09:01 UT
Partial Eclipse Begins   00:15 HST   10:15 UT
Total Eclipse Begins   01:57 HST   11:57 UT
Greatest Eclipse   02:01 HST   12:01 UT
Total Eclipse Ends   02:02 HST   12:02 UT
Partial Eclipse Ends   03:44 HST   13:44 UT
Penumbral Eclipse Ends   04:58 HST   14:58 UT

Timing for the 4Apr2015 total lunar eclipse

Total Lunar Eclipse

Early on the morning of April 4th a total lunar eclipse will be visible across the Pacific. Sky watchers in Hawaiʻi will be able to observe this event from beginning to end.

Total Lunar Eclipse 14Apr2014
The total lunar eclipse on Apr 14, 2014, Canon 6D on 90mm f/12 APO
This eclipse is just barely total with an umbral magnitude of 1.0008. The northern edge of the Moon will be barely inside the umbra and probably much brighter than the south hemisphere. The eclipse is also quite short, with a total phase lasting only four minutes. Compare this to the next total eclipse of 2015 where totality lasts over an hour.

Maximum totality will occur at 12:02UT or about 02:02HST. First contact will occur at 11:01HST on the evening of the 3rd, with umbral first contact a little after midnight at 00:15HST. It is this umbral contact that will be the first obvious effect of the eclipse to a visual observer, a notable notch out of the Moon.

Observing a total lunar eclipse requires no special equipment, simply the desire to look up. The most useful piece of equipment will be a reclining chair or some other method of staying comfortable while watching the sky. A pair of binoculars or small telescope can provide beautiful views of the Moon during an eclipse. Photography is somewhat more challenging, but not that difficult. Focal lengths of around 1000mm will fill the field of most DSLR cameras allowing photos like that shown here.

Penumbral Eclipse Begins  11:01 HST   09:01 UT
Partial Eclipse Begins   00:15 HST   10:15 UT
Total Eclipse Begins   01:57 HST   11:57 UT
Greatest Eclipse   02:01 HST   12:01 UT
Total Eclipse Ends   02:02 HST   12:02 UT
Partial Eclipse Ends   03:44 HST   13:44 UT
Penumbral Eclipse Ends   04:58 HST   14:58 UT

Timing for the 4Apr2015 total lunar eclipse
The entire eclipse will be visible during the night, quite convenient for amateur and casual sky-watchers.