A Darker View

Today Mercury will be at maximum eastern elongation, as high in the evening sky as it will appear for this current apparition. After today the planet will slide back into the sunset, passing through inferior conjunction on September 30th and reappearing in the dawn during the first weeks of October.

Continue reading Mercury at Maximum Elongation…

A small box with my name upon it, sitting on the shelf in our shipping department for me to pick up. The procedure is simple… Grab the box and note your receipt on the clipboard hanging at the end of the shelf.

Overpackaged

A ribbon cable, one of three in a shipment.

I have been awaiting this shipment for a while now, hoping to continue a project to build a new test fixture. But the shipment is not complete. The latest box contains three little bags, not what I am really hoping for.

What is it this time? I open the box, open one bag, take out the anitstatic bag within that and find… A ribbon cable.

I just have to sit back and stare at this in sheer disbelief.

The disbelief has been building for a week now as the boxes have appeared in our shipping department one by one. A single order, a pair of A/D units and accessories. I have now received four separate boxes, all delivered FedEx, and not received the actual A/D systems themselves, only the various accessories.

One box with three double bagged ribbon cables that weigh all of a few ounces each and are ten inches long. All of the accessories I have received in the four boxes could easily have fit in one box. The anti-static bag is even more unbelievable. These metallized mylar bags are not cheap. Why would you put one around a component that is totally immune to static damage? A ribbon cable with connectors at each end? To be static sensitive it would have to at least contain a semiconductor component of some sort. One transistor? Then you seal a poly bag around that? At least it was brown paper and not foam peanuts used to fill the rest of the box.

With this order National Instruments has by far topped the worst overpackaging I have seen to date. Quite something in the electronics industry where overpackaging is the norm. It used to be Digikey was the worst I had ever seen, but they have gotten much better over the last few years, shifting to all brown paper packaging aside from the plastic bag around the parts themselves.

How is it even possible to receive a small order in four separate FedEx shipments and not even get the primary thing you ordered? To Hawaiʻi? How can you construct a shipping system that inefficient and make any profit after paying the shipping bills? It is not like any of the accessories do me any good without the main units, no need to rush them. One box with everything would be quite acceptable.

Still waiting for the A/D units. Maybe tomorrow?

The satellite views of the central Pacific are endlessly fascinating. Three major hurricanes surround the Hawaiian Islands. Social media continues to buzz, with re-posts of the imagery.

So far only minor effects in the islands… Major surf on the northern and eastern shorelines, closed beach parks, and lousy observing weather keeping the telescopes shuttered.

Central Pacific Hurricanes

Three hurricanes in the central Pacific, GOES West 4km IR image from 2Sep2015

The secondary mount is often one of the most complex pieces of a telescope build.

Secondary Mount

Side view of the Travel6 secondary mount

The mount must be small, not blocking any more light than the secondary mirror. It must be adjustable to allow tip, tilt, and centering of the secondary mirror. it must be rigid, able to hold the adjustment precisely once the telescope optical alignments are made.

Thus I have put together a new design for myself, to be used in the 6″ travel ‘scope under construction. The design is simple and robust, a pretty solid little device using the lessons I have learned across the years. It draws upon ideas from many other secondary mounts I have seen.

Secondary Mount

Rear view of the Travel6 secondary mount

The body is square as this is easier to clamp during each of the manufacturing operations. The square is as large as possible to provide a stable mount, with the corners beveled just enough to stay behind the secondary.

The mount shown here is designed for a 31mm minor axis diagonal mirror. Thus the body of the mount is one inch square with 0.1″ beveled off each edge. This could be scaled up or down for another size diagonal mirror. The overall length of the entire mount is as short as possible. A bar of aluminum was cut to size and beveled first. A four inch bar yielded two complete mounts. I left the machined surfaces a bit rough to break up the smooth surfaces, better to hold paint and to avoid reflections.

There are four adjustment screws here. This allows for a simpler adjustment scheme than a three screw arrangement. With three screws adjustments are often made using all three screws at once. A four screw scheme allows the screws to be adjusted in pairs to effect moves in one axis at a time.

Secondary Mount Drawing

Mechanical drawing for the Travel6 secondary mount

I have made mounts with spring loaded screws in the past. They are easier to adjust, no need to loosen and tighten opposing screws. But they are not as rigid, the careful adjustment more likely to drift. This mount uses pusher screws that must be loosened and tightened in pairs.

Shallow pockets are drilled into the rear of the wedge for the tip of each adjustment bolt. this prevents any rotation or the wedge as long as the adjustment bolts are tight.

Secondary Mount

Top view of the Travel6 secondary mount

Vertical adjustments will be made by adjusting the height of the standoffs used to mount the secondary, or perhaps by shimming with a washer or two. The two mounting screws will sit in slotted holes allowing the secondary to be aligned with the focuser.

The center screw sits in a counterbored hole, only a small section of the shaft near the head is constrained. This allows it to tip slightly and allow the adjustments. A split lockwasher keeps some back tension during adjustments.

The secondary will be attached with RTV adhesive. The corners of the mount line up with the edges of the secondary making alignment quick and simple. All that is needed is a coat of flat black paint on the sides to prevent odd reflections in the optical path.

Hurricanes whirling past, satellites breaking up overhead. I am reluctant to ask… What is next?

Hurricane Ignacio

Hurricane Ignacio as it passes the Hawaiian Islands. GOES West 1km visible light image from 1 Sep 2015

Even better video of the breakup of Cosmos 1315 over Hawai’i. Taken by Josh Lambus, of course.

Be sure to hit the HD button!

One of the more sublime sights seen from Mauna Kea is the shadow of the mountain rising through the mist and haze at sunset. One of the more sublime sights in the heavens is the Earth’s shadow crossing the face of the Moon, a total lunar eclipse. It is possible to combine these two phenomena if the timing is right, the Earth’s shadow seen twice.

Eclipse in the Mauna Shadow

The eclipsed moon rising in the shadow of Mauna Kea, February 20, 2008, photo by Alex Mukensnable, used with permission

The moment of totality in a lunar eclipse occurs when the full Moon is directly opposite the Sun in the sky. By simple geometry this same anti-solar point is where the tip of the mountain’s shadow will be projected for an observer standing near the summit of the same mountain. If the eclipse is in progress at sunset, and you are standing on the summit of a suitably prominent mountain, you will see the Earth’s shadow both in the sky and obscuring the Moon.

Back on Feb 20th, 2008 the timing was right. A friend of mine, Alex Mukensnable, noted the timing and set up to catch the eclipsed Moon rising in the shadow. The result was a great set of photos. The photo is nice enough as a still, be he did more than that, he shot the event as a timelapse and assembled a video of the rising Moon.

There are several possible variations depending on the timing with this sort of event… If the Moon was at the height of totality rising it would also be right at the tip of the mountain shadow as it rises. This is a relatively rare event as the timing requirements are tight. Unfortunately it would also be quite dim, darkened by the shadow, and not easily seen as it rose.

As lunar eclipses are long events, taking several hours to complete, the likelihood of the Moon being in at least the partial eclipse phase at sunset is fairly good. Still a rare event, but not extraordinarily so. Thus for a single site, the summit of Mauna Kea this even happens in both 2008 and 2015.

As the Earth’s shadow is about 2.6° across at lunar orbit, the closest a partially eclipsed Moon will be seen from the the very tip of the shadow is about 1.3°. This is a bit less than three lunar diameters. Of course these numbers will vary a few percent depending in the distance to the Moon which changes as it makes its elliptical orbit.

The Moon moves slowly across the sky from west to east, thus before totality the Moon would be above the tip of the mountain shadow. After totality, with the eclipse ending, the eclipsed Moon will be in the shadow. Placing the Moon in the shadow also makes it easier to see, the bright crescent a better contrast to the dark shadow. This is the case for the 2008 eclipse captured by Alex.

Of course you could reverse all this timing and watch the event at moonset and sunrise. If the eclipse was just starting at dawn it would again place the eclipse in the mountain shadow.

Another important point to remember is that the shape of the mountain’s shadow has little to do with the shape of the mountain. The shadow will always be a neatly conical form due to the effects of projection.

What brings this event back to the fore is that the timing will soon be correct to see this same event again. The total lunar eclipse of Sept 27th, 2015 will be a bit of a dud for Hawaii, most of the eclipse already over as the Sun sets and the Moon rises over the islands. However, this event will feature very similar timing to the 2008 eclipse. The Moon will still be in partial eclipse when it rises. As it rises a short time after full Moon it will again be deep in the shadow of Mauna Kea as it comes over the horizon.

You know where you will find me on the evening of the 27th. Now I just need some clear weather that day.

So last night a Russian satellite burns up over Waikoloa… And I miss it!!

Some of my friends and co-workers did not, asking me what it was this morning after personally witnessing it. There are videos all over Facebook. I am so envious!

The satellite was Cosmos 1315, a Russian signals intelligence mission launched in 1981. It re-entered just west of the Big Island about 11pm HST last night.

I have embedded a video below, the language is more than a bit rough, a few f-bombs. The language goes to illustrate just how dramatic the event was. Aside from the unfortunate choice of vertical format, the video is surprisingly good.

Several items stand out in the video…  The giveaway that it is man made is the very slow speed of the object, not the high speed typical of most meteors.  You can also see the satellite coming apart, fragments breaking away.  Larger meteors can also do this, breaking up upon re-entry.

The guy (I believe Chris Jardine) identifies the object as a meteor, a good guess. I first thought meteor when I saw the video.  I received word a bit later from Steve Cullen who passed along a link to information on the satellite.  The gal thinks comet? We need to do more public outreach and education around the island!

Gold Lace Nudibranch

A gold lace nudibranch (Halgerda terramtuentis) in a cave at Golden Arches

A beautiful image from the NOAA-NASA GOES Project of a full disk Earth. Off to the west of the islands you can see the re-formed Hurricane Kilo, to our immediate east if Ignacio, with Jimena right behind. The forecast calls for tropical storm force winds to begin on the island as soon as tonight. Also visible is an active region of thunderstorms off the Mexican coast, the spawning ground for the next hurricane.

Click on the image for full glory!

Three Pacific hurricanes visible in this full disk weather image from the NOAA-NASA GOES Project

Three Pacific hurricanes visible in this full disk weather image from the NOAA-NASA GOES Project