A Darker View

GenPIC First Code Release

I have had hardware for a while now, it is about time I release some firmware that actually runs it.

GenPIC Development Setup — The development setup in use generating the first software release for the GenPIC utility PCB

Here it is!

The first GenPIC code revision is a test and demonstration release. It contains support for one serial port, an LCD character display, user input including the encoder and pushbuttons, the indicator LED’s, timer generation, analog input including onboard temperature readout.

Also included is a serial command interpreter implementing a serial interface usable with any serial terminal. There is also a user interface system with a state setup that provides multiple input screens. This should handle a wide array of basic control capabilities, either using the serial port or through using the LCD screen and the encoder.

The code allows you to exercise many of the basic functions of the hardware and provide a framework on which a real application can be built.

It works, it runs, it looks fairly good. Now time to make something useful with it…

First code release
11Feb2017

Code Rev0.1

There will be additional code releases as this project continues, as always check the GenPIC main post for the latest!

Venus Becomes a Crescent

Even when Venus is high in the sky and well placed for observation I will seldom take the effort of turning a telescope towards the planet. Why? Because Venus is pretty boring to look at. Perpetually cloud covered it has all the detail of a cue ball. It is a white disk with nothing of note to be seen. Yeah, pretty boring. Now turn the telescope to Jupiter.

Crescent Venus — Venus approaching inferior conjunction, 24Dec2013

One exception to this occurs when Venus is approaching, or just emerging from inferior conjunction. As the planet passes between the Earth and the Sun we are looking at the nighttime side of the planet, with only a little of the daytime side to be seen. As a result Venus will appear as a brilliant crescent.

This begins as the planet passes maximum eastern elongation, about two months before inferior conjunction. At this point the planet is seen from the side with respect to the sunlight, the planet will be about half illuminated. In the weeks after maximum elongation the planet will appear ever more crescent.

Venus 28May2012 — Venus on 28May2012, about 12°44′ from the Sun

The last weeks before conjunction, as Venus is very low in the sunset, or the first weeks after conjunction as it sits very low in the dawn are the most interesting. During this time the planet is a very fine crescent, quite a beautiful sight in the telescope. Many observers, including myself, have made a point to observe Venus at this time, the one time this planet really becomes interesting to view.

Imaging Venus in the Daytime — Imaging Venus in the daytime a mere 12°44′ from the Sun.

As the planet is quite low in the sky it makes it a challenging telescopic target and distortion by the atmosphere can be troubling, blurring the view.

It is possible to enjoy this sight in the daytime, while the planet is high in the sky, the seeing can be better and the view sharper. Of course this also occurs when the planet is near the Sun, thus extreme caution should be practiced at the telescope to avoid any direct sunlight and possible eye damage.

Planetary Drawings by Galileo — A page from Galileo’s 1623 treatise The Assayer—Il Saggiatore

The phases of Venus are quite interesting from a historical standpoint. The phases of Venus clearly show that the planet revolves around the Sun. The phases were one of the primary arguments used by Galileo in his treatise The Assayer—Il Saggiatore published in 1623, where he lays out many of his ideas on science itself and how observation and experimentation should be primary.

While the the evidence challenged prevailing ideas of the time, some astronomers attempted to explain the phases of Venus by any other means to preserve their Earth centered universe, which led to rather tortured models of planetary motion. But it was clear to most that Galileo was right, the simple and elegant answer was that the Sun lay at the center. The orbits of Mercury and Venus, the phases, along with other observations like the moons of Jupiter, were hard evidence that few could ignore.

In 2017, eastern elongation occurred on January 12th. By now Venus has begun to show a substantial crescent, about 30% illuminated if you look today, Feb 12th. Over the next few weeks as the planet sinks into the sunset, the crescent aspect will thin dramatically.

By the end of February the planet will be only 17% illuminated, another week after that it becomes only 11%, by which time the planet will be difficult to spot in the sunset. Inferior conjunction will occur on March 25th. A couple weeks later and it will be possible to spot the planet in the dawn and observe the now thickening crescent.

Venus Events for 2017
	Date UT	Separation	Mag
Maximum Elongation	Jan 12	47.1°E	-4.4
Inferior Conjunction	Mar 25
Maximum Elongation	Jun 3	45.9°W	-4.3

Source: NASA Sky Calendar

Pakoda

To Play in the Snow

There are days when it seems like the entire island population comes to Mauna Kea. This is certainly the case on a snow day, the first day the road is open after a fresh snowfall will see a crowd of folks ascending to the summit to play in the snow.

Loading Snow — Loading pickup trucks with snow for export from the mauna.

This winter the snow came for Christmas, several feet of snow just before the holiday. MKSS was able to plow through the snowdrifts and open the road for the public on Christmas Eve. The result was predictable, hundreds drove up to the snow to enjoy a white Christmas.

One local tradition is the hauling of snow from the summit to the beach. On some days dozens of pickup trucks can be found on the summit, or filled with snow making their way down the mountain road. The snow will be the basis of parties and games on the beach or in green tropical lawns. Online you can find photos of snowmen under palm trees or snowball fights and smiling keiki on Hilo yards.

Continue reading “To Play in the Snow”

Full Moon

Full Moon will occur today at 14:33HST.

With this full Moon a penumbral lunar eclipse will also occur, visible across Europe and Africa, and partially visible from North America. None of this eclipse will be visible from the mid-Pacific including Hawaiʻi. For the islands the next good lunar eclipse will occur Jan 31, 2018.

Continue reading “Full Moon”

TMT Opponent’s Alternative Facts

A number of other commentators are noting the use of alternative facts by telescope opponents. While I have commented a few times here on DV about the issue, it is heartening to note that I am not alone in this.

Ahu — An ancient ahu (shrine) at 11,000ft on Mauna Kea

Environment Hawaii has published a number of articles that cover the ongoing TMT contested case. The latest is quite critical of Sierra Club Director Marti Townsend’s recent testimony. The article is quite forthright in noting a list of factual errors in her testimony.

Many of the witnesses have testified on cultural and religious issues, no problems here, these are personal matters where there is no objective truth. But over and over we have seen witnesses make very specific physical and scientific claims that are simply wrong. It will be interesting to see how these inaccuracies are addressed in the findings of the hearing officer.

No, Mrs. Townsend, there are no glaciers on Mauna Kea. There used to be, about ten thousand years ago, but they are gone now.

ATM Gallery

Gluing the Mirror Box — Gluing the mirror box for Deep Violet, and 18″ f/4.5

Mirror Cell — The 18 point mirror cell, built to the plans from Barry & Kriege

The Strap — The primary mirror support strap

Ground Board — The ground board with center pivot and teflon pads in place

Drilling a Pocket — Drilling a pocket to accommodate a carpet pad in the side of the rocker box

Nearly Ready — Deep Violet fully assembled and nearly ready for dark

Deep Violet at Sentinel, Arizona for the 2015 Pierre Schwarr Star Gaze

Axis — Detail of the tripod head, latitude adjustment and the RA and declination axis

Set Up — Primero setup at Jarnac Observatory among a friendly crowd of other telescopes

Binocular Parts — Stripping and cleaning the 14×100 binoculars

Celestron Cometron in Parts — A completely disassembled Celestron Cometron telescope

Upper Truss Clamp — Detail of the upper truss tube with the lever type latch

Threadsert — Detail of the brass threadserts used to hold the lower truss clamp

12.5" Dobsonian — A 12.5″ dobsonian telescope after the refit

Machining the Mirror Cell — Machining the mirror cell from a piece of scuba tank

Empty Mirror Cell — The mirror cell prior to installing the primary mirror with the focus knob at the back of the strut

Mirror Mount — A very standard design for the mirror mount

Front View — A front view of Makaʻiki ready to observe

Strut Extended — Makaʻiki with the main strut extended for use

First Light for Makaʻiki — Makaʻiki under the stars for the first time at Hale Pōhaku on the side of Mauna Kea

Pier Forms — The forms for the pier upright filled and leveled

Pouring the Upright — Bill Lofquist pouring concrete into the upright part of the pier

Complete Pier — The completed pier with a telescope atop

Orange Tube Corrosion — Looking at what remains of the paint on an old Celestron C8 orange tube telescope

Stripping the Orange — The orange paint just crumbles away under a few sweeps of a power sander

Ready for Paint — Parts of the mount prepped and taped for painting

Drying Paint — Paint drying on the front and rear castings of the old orange tube

Restored C8 — A restored Celestron C8 on a similarly restored TeleVue Renaissance mount.

Transit Telescope — The C8 set up along the old Saddle Road for Mercury Transit

Secondary Cage — Re-assembling the secondary cage on the 20″ Obsession. The truss tube clamps still need to be cleaned up and re-installed, same with the focuser.

Rusted Hardware — The rusted hardware removed from a 20″ Obsession telescope

Fixing the Clamp — Opening up the truss tube clamps by widening the slot with a hacksaw.

Secondary Mount Fix — A fix for the secondary mount

Clamps — Clamping the rocker box of a 20″ Obsession

Primary Mirror from the Back — Installing the primary mirror. This is a Galaxy Optics 20″ f/4. Oddly enough Sky Hudek, the son of John Hudek, the owner of Galaxy is a good friend and dive buddy.

Trunk Handles on the Rocker Box — Trunk handles added to the rocker box to make picking it up and loading it in a vehicle easier. They are mounted just high enough to avoid the wheelbarrow handles when installed.

My copy of The Dobsonian Telescope by David Kriege and Richard Berry

20" f/4 Obsession — 20″ f/4 Obsession #004 fully assembled for the first time in over a year. Ready for alignment and use!

Hammered

Various types of hammers await use in the Keck machine shop

Taming a Rotary Encoder

The rotary encoder is a popular input device for many microcontroller devices. A knob that can be used to increase or decrease a setting with a nice tactile click for each increment. You can even get an integral pushbutton, just rotate for the setting then press the same knob to enter. With some clever programming you can create a one device user interface using only the encoder.

I have integrated a rotary encoder in the GenPIC utility board. With the combination of an LCD display and the rotary encoder you have all the ingredients for a functional user interface arranged neatly for a panel mount unit.

In the past I have simply set an interrupt to fire on the edge of one channel, then sampled the opposite channel to detect the direction. With the addition of a small delay to debounce the result. This worked well in previous devices, but this time I encountered trouble, the direction sampling was erratic, the value going up when it should have gone down and vice-versa.

Breaking out my logic analyser I found out why, this particular encoder proved to be somewhat noisier than I had seen in the past, with notable periods of bouncing signals.

Continue reading “Taming a Rotary Encoder”

Venus Events for 2017