The Dobsonian Telescope

In restoring a 20″ Obsession telescope I found myself pulling a book from the shelf that had not been opened in a while. David Kriege and Richard Berry’s The Dobsonian Telescope – A Practical manual for Building Large Aperture Telescopes is a book I once read cover to cover.

The Dobsonian Telescope
My copy of The Dobsonian Telescope by David Kriege and Richard Berry
The information here was critical in the success of my building Deep Violet, my 18″ telescope. Within the pages of this book are plans and drawings of the important bits as well as detailed discussions of what does, and does not work, when building a telescope.

The Dobsonian Telescope is the primary reference for those building large amateur telescopes. This book, along with the design revolution that went with it, put large telescopes in the hands of countless amateur astronomers. These telescopes extended the capabilities of amateur observers immensely, allowing spectacular views of deep space objects that were only fuzzy smears in the eyepiece before. Want to see the spiral arms of galaxies? A 20″ telescope can do that!

As I perused my well thumbed copy I was surprised to find bits of my own telescope plans used as bookmarks. There was dust on the top of the pages, but I still remembered where I disagreed with Kriege in the dimensions of the mirror box, or how to place the truss tube clamps. I may have deviated from the plans shown here in some aspects, but in other parts of the design I directly used the dimensions shown in the book.

So many old memories, good memories. Pursuing an art that has been around for four centuries, combining bits of wood and glass to make an instrument that can reveal our universe. Sure you can simply buy a very good modern telescope. But it is hard to overstate the pleasure of building one yourself. This is an art that can still be done in a garage, with tools available at the local hardware store, with results that can rival or even surpass something purchased from a catalog.

Solar System Walk 2016

Walking from the Sun to Neptune is easy… At least when they are set up in a scale model along main street Waimea.

A fun day… The Sun, telescopes, the planets, a few asteroids represented by meteorites, and plenty of activities for the kids. It was a great day to be in Waimea as CFHT and Keck put on the Solar System Walk 2016…

Observing at Kaʻohe

A dark night under the stars! It has been too long… Why not?

Obsession at Kaʻohe
The 20″ Obsession telescope awaiting full dark at Kaʻohe, on the side of Mauna Kea

After all the work restoring the 20″ Obsession it was time to get it out under the stars for a decent observing run. During the many hours of work I had looked forward to simply using this telescope for a bit. While it would eventually be stored at the observatory and used for outreach, it seemed a shame not to spend a night or two under the stars with this instrument. Not like I need a 20″ telescope, my 18″ is just fine, but I loaded it up just the same, leaving Deep Violet in the garage.

Obsession at Kaʻohe
The 20″ Obsession telescope being set up at Kaʻohe, on the side of Mauna Kea

My favorite close by site is KaʻOhe, taking only a twenty minute drive from home to reach. At 5,700 feet on the side of Mauna Kea nearby home does not mean second rate. I really like this spot, the view is spectacular with the coastline below and the Mauna Loa and Hualālai volcanoes dominating the horizon. The entire southern horizon is unobstructed, allowing observations of southern objects right down to the horizon.

Better yet, recent rains meant green grass and a spot near the road maintenance gravel pile was hard packed rock, no dust! The area had even been mown recently! I sometimes have a few uncharitable words to describe DLNR, but not this evening.

Continue reading “Observing at Kaʻohe”

‘Heartbeat Stars’ Unlocked in New Study

NASA press release

Heartbeat Star
The overlaid curve in depicts the inferred cyclic change in velocities in one such system, called KIC 9965691, looking something like the graph of an electrocardiogram. Credits: NASA/JPL-Caltech
Matters of the heart can be puzzling and mysterious — so too with unusual astronomical objects called heartbeat stars.

Heartbeat stars, discovered in large numbers by NASA’s Kepler space telescope, are binary stars (systems of two stars orbiting each other) that got their name because if you were to map out their brightness over time, the result would look like an electrocardiogram, a graph of the electrical activity of the heart. Scientists are interested in them because they are binary systems in elongated elliptical orbits. This makes them natural laboratories for studying the gravitational effects of stars on each other.

In a heartbeat star system, the distance between the two stars varies drastically as they orbit each other. Heartbeat stars can get as close as a few stellar radii to each other, and as far as 10 times that distance during the course of one orbit.

Continue reading “‘Heartbeat Stars’ Unlocked in New Study”

Long-term, hi-res tracking of eruptions on Jupiter’s moon Io

UC Berkeley press release

NIRC2 image of Io
A NIRC2 image of Jupiter’s Moon Io
Jupiter’s moon Io continues to be the most volcanically active body in the solar system, as documented by the longest series of frequent, high-resolution observations of the moon’s thermal emission ever obtained.

Using near-infrared adaptive optics on two of the world’s largest telescopes — the 10-meter Keck II and the 8-meter Gemini North, both located near the summit of the dormant volcano Maunakea in Hawaii — UC Berkeley astronomers tracked 48 volcanic hot spots on the surface over a period of 29 months from August 2013 through the end of 2015.

“On a given night, we may see half a dozen or more different hot spots,” said Katherine de Kleer, a UC Berkeley graduate student who led the observations. “Of Io’s hundreds of active volcanoes, we have been able to track the 50 that were the most powerful over the past few years.”

Continue reading “Long-term, hi-res tracking of eruptions on Jupiter’s moon Io”