astronomy – A Darker View

Observing from the Pali

With four nights in the park I planned to do a little observing along with the planned hikes. situated on the south face of the island the park offers a view of southern skies objects that cannont be matched anywhere else in the 50 states.

Makaʻiki Mk2 setup at the Hilina Pali viewpoint in Hawaiʻi Volcanoes National Park observing the southern sky

The plan was simple… Getup in the wee dark hours and drive the 20 minutes to the Maunaiki Trailhead. I could then setup my little 6″ travel scope and observe the southern sky.

Arriving I at the trailhead I was not happy, unusual morning clouds covered the sky, not a star to be found. This is the Kaʻu Desert!! It is supppose to be dry and clear in the morning. My cursing had no effect on the clouds.

A quick look at the satellite imagery and I headed further down the road to the Halina Pali Overlook with some hope. It was dicey, but I was already driving around in the middle of the night, why not?

And behold… Clear skies. Somewhat. It had clearly rained in the night as everything was wet. But at least some of the sky was beautifully dark and clear. As long as the rainclouds looming in the east held off I could do what I suffered such an early alarm for.

Quickly setting up the little scope I found conditions were not bad, though I did have to hop about a bit to avoid some drifting clouds. There was usually some part of the sky clear… Use it!

NGC 5286 – Bright and obvious, small at 2′ diameter, unresolved, round with a bright center, the 4.6 magnitude M Cen is 4′ southeast

M68 – Bright and obvious, 3′ diameter, rich, not resolved, round with a bright and well concentrated core

NGC 4361 – Small, bright and obvious, a round 1′ disk with a bright central star and well defined extents, no color noted, no other structure noted

NGC 5139 – A spectacular swarm of stars, very bright and easy to sweep up, large at 30′ diameter, resolved, extremely rich, well concentrated with a exceptionally dense center that fades radially into a fine mist of stars, one cannot fathom such a region of the cosmos, a place where our mere common sense fails utterly
6″ RFT Makaiki Mk2, Hilina Pali Overlook HVNP, 9 Jan 2025

Omega Centauri, NGC5139, sum of 31 x 1min exposures, AT6RC and Canon 60D

Close to astronomical dawn the clouds swept across the sky, a curtain to end the show. A few scattered raindrops had me hurrying to pack the gear back in the vehicle. I was considering what to do next when the rain came in ernest, a steady rain that washed over the windshield.

The drive back into the main section of the park proved fruitful as I found the usually crowded trails deserted in the early morning rain.

Waiting for T Coronae Borealis

Things change in the sky. Contrary to the stenuous assertions of some, the night sky is not constant, it changes. Stars move, sometimes fairly rapidly, stars fade, and sometimes brighten dramatically.

Then there are novae, stars the flare to a brilliance far beyond their normal lustre. Such a star is T Coronae Borealis, or T CrB for short. This star is a recurrent nova, a star that flares to brilliance once or twice every century.

Sometimes called the Blaze Star, T CrB is normally a dim 10th magnitude star, a star that requires a small telescope to view, lost in a field filled with similar stars. A few times in the annals of astronomy the star has blazed to second magnitude, about 1500 times brighter. In 1866 and 1946 the star rivaled nearby Alphecca, the brightest star in the constellation of Corona Borealis. It may also have been observed in 1217 and again in 1787 giving a rough period of about 80 years.

T CrB is a white dwarf that is stealing material from a stellar companion, a red giant near the end of its own fuel. When that material builds up enough the white dwarf flares into temporary brilliance as a fusion reaction tears across the surface of the stellar remnant. The cycle repeats over the centuries causing these regular novae. Eventually the accumulating mass will be too great and instead of a recurring nova the star will meet its final end as a type Ia supernova.

I am of course among those awaiting the eventual nova. Yesterday evening I took a few images of the field to capture the scene. Hopefully I can take the images again to get a before and during image of T CrB.

Last year T CrB started exhibiting behavoirs similar to what had been measured just prior to the 1946 eruption. As a result we expect the star to go nova on schedule this year, most likely in the next month.

We have been waiting, stargazers keeping an eye on the constellation all summer.

Not yet.

Awaiting the recurring nova of T CrB — T CrB on the evening of 22 Aug 2024… Still about 10th magnitude, no nova yet. The 4th magnitude star Epsilon CrB at the top.

A Changing Sky

Gazing up at the sky while reading the old texts one would not be amiss in believing that the stars never change. Indeed there are many who insist vehemently that the stars are eternal and unchanging. But the stars do indeed change, often quite visibly, sometimes within the span of a human lifetime.

VLT/SPHERE image of the star L2 Puppis and its surroundings — A VLT/SPHERE image of L² Puppis showing the enveloping cloud of gas and dust representing an early stage planetary nebula. Image credit ESO/P. Kervella used under Creative Commons 4.0

One such star is L₂ Puppis.

A bright star, one of the few naked eye variable stars that could be seen to fade and reappear without the aid of a telescope much like the far more famous stars Mira and Algol. On star charts the star is found prominently drawn at magnitude 4, buf if you attempt to locate it today you will not find it without the use of a telescope.

I first encountered this star quite recently while starhopping through southern Puppis with an 8″ telescope from the driveway. The chart showed two bright stars close together, L₁ Pup and L₂ Pup, while the view in the finder ‘scope showed only one bright star.

Segment Exchange

Lifting segment 4-76 out of the Keck 2 primary mirror for re-coating and repair — Lifting segment 4-75 out of the Keck 2 primary mirror for re-coating and repair

Of Green Stars…

Wandering the sky using a telescope and a field guide published in 1844, the better part of two centuries ago, is… uhhm… interesting. In mid-April the classic winter constellations are dissapearing into the sunset, with constellations like Monocerus and Puppis well placed for observing from my driveway just after dark. On my observing table is a reprint of that 1844 field guide, The Bedford Cycle.

Working through the entries I come to the entry for a double star Argo Navis 72 P. VIII, a designation from a very old catalog. It takes a few moments research to convert 72 P. VIII to the slightly more modern catalog number HD 71176. Modern? The Henry Draper Catalog was first published by Harvard Observatory in 1918, still over a century ago.

With the HD number I can look up the position on a modern chart and spend a few moments star-hopping the Astrola to the correct star. This double star is now located in the constellation Puppis after the ancient and absurdly large constellation Argo Navis was broken up into Puppis, Vela, and Carina.

Kinipōpō – A Small Ball ‘Scope

For the last couple years I have been exploring 3D printed telescope designs. The latest result of this oddessy is Kinipōpō, a 4.5″ f/4 Newtonian using a entirely 3D printed ball mount design.

The Hawaiian word kinipōpō translates as ball or sphere.

A ball telescope offers a number of advantages, the first of which is ease of use. It is simplicity itself to aim at a target, no odd controls, no weird angles, just freely push the ‘scope to the target. As the tube can be freely spun the eyepiece can always be positioned for easy viewing.

The design is an RFT, or Rich Field Telescope. This type of ‘scope is designed to be a low power, wide field ‘scope ideal for enjoying sweeping the sky and providing views rich with innumerable stars. It is not a good ‘scope for planets, the magnification is far too low. It’s prey is large, bright targets, star clusters, bright nebulae, or even the dark nebulae silhouetted against the rich starfields of the Milky Way.

Another ideal target is bright comets. My prototype providing pleasing views of comet C/2022 E3 ZTF a month before preihelion and maximum brightness.

The short focal length does create coma issues around the edge of the field, stars near the edges of the field smear a bit and will not focus. The problem does not seem too objectionable, but it is there.

The design is inspired in part by the classic Edmunds Optics Astroscan telescope, in being both small, portable, and simplicity to use. On the other hand the design offers a number of improvments over the Astroscan. Primarily the ‘scope offers an increased aperture of 114mm compared to the Astroscan’s 105mm, while being very close to the same overall size.

The scope costs about $200 to assemble, the largest chunk of that being the primary mirror. While the needed plastic filament for the 3D printer is cheap, it does take quite a bit of time to print. The largest part, the spherical shell requires over 60 hours on the printer, with many of the other parts being overnight prints. Assembly is not difficult, mostly cleaning up the plastic prints, heat setting a number of brass threaded inserts, and a bit of epoxy here and there.

Three of these little telescopes have been built, and three have been given away. I get photos of them every now and then, fun little telescopes under a dark sky.

A simple helical crayford telescope focuser

Mirror test stand with 6" telescope mirror

Truss tube clamp on the Kinipōpō ball telescope

Three copies of the Kinipōpō ball telescope

Waiting for Dark

Awaiting dark with the 20" telescope — Andrew Unger beside the 20″ Obsession while waiting for properly dark skies at Kaʻohe

A View from the Past

As an evening pastime in these COVID restricted days I have been delving into the past again. Again reading the work of an amateur astronomer from long ago.

Frontspiece of Bedford Catalogue, 1844, Capt. William Henry Smyth

I had previously read through the work of Rev. Thomas Webb, a vicar and amateur astronomer active in the late 1800’s. Webb frequently refers to the work of a yet earlier observer, Capt. William Henry Smyth.

Retired British Navy Captain Smyth was a backyard observer, gazing at the stars with a 150mm refractor from a garden behind his home in Bedford England. His telescope was quite good for the time, made by Tully of London, the best money could buy. This telescope was eventually purchased by the British Government to be used in the 1874 transit of Venus expedition to Egypt and the 1882 Venus transit in Jamaica. It now sits in the collection of the Science Museum, London.

Capt. William Henry Smyth's Telescope at Bedford — Capt. William Henry Smyth’s Telescope at Bedford

Smyth published two volumes on astronomy in 1844 under the title A Cycle of Celestial Objects . Volume II of this set, commonly called The Bedford Catalogue or The Bedford Cycle, contains descriptions of more than 850 double stars, clusters, and nebulae, serving as a guide to what may be observed with a small telescope. The Bedford Catalogue became the standard at-the-telescope reference for other amateur observers for many decades until it was generally replaced by Webb’s Objects for Common Telescopes.

Andrea Ghez awarded the Nobel Prize in Physics

UCLA scientist and Keck Observatory user Andrea Ghez has been awarded the Nobel Prize in physics. She shares the prize with two other researchers; Roger Penrose, a British mathematical physicist and German astrophysicist Reinhard Genzel, for work in black holes and galaxies.

Andrea Ghez presents a community lecture at the Honoka'a People's Theater — Andrea Ghez presents a community lecture at the Honoka’a People’s Theater

There is no Nobel prize in astronomy and the Nobel in physics has traditionally gone to scientists involved in hard physics for discoveries of some new theory or subatomic particle. It is only in recent years that we have seen a few Nobel prizes awarded to astronomers.

Andrea is the only Nobel recipient I have known personally. I can say one thing, she completely deserves it. While her scientific achievements may justify the award, her activities beyond the science are just as commendable.

Star Types

I have been observing a lot of stars during my driveway sessions at the telescope lately. Some of these are new to me, will have to look them up and hunt them down…