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.

Morning Observing

First quarter moon… Telescope time.

Observing Table
The observing table under red light.

I find myself reliably rising early, often around 4am, something that seemed to have begun during the pandemic. Those who knew me in my younger years may find this a bit unbeliveable, I used to hate mornings, but now?

The other factoid about island mornings. It is almost always clear. The afternoon and evening clouds have dissipated and clear skies are the rule.

Combine these bits with a love of the sky and the result is morning observing sessions, often half a dozen mornings will be spent out with a telescope in those couple weeks the Moon is absent from the morning sky.

Get up, shrug on some ratty old clothes, and wheel the telescope out of the garage. The ‘scope of choice is almost always the old Astrola, even with larger and more sophisticated telescopes available there is just something about using that old manual ‘scope that I find satisfying.

At the telescope in the driveway again
At the telescope in the driveway again

Perhaps the lack of computer or digital setting circles means it is my own skill enabling my path among the stars. The Astrola does have manual setting circles, but I rarely use those. A star chart, a finder, and starhopping allow me to wander through rather than jump about… I just see more, often stumbling across unexpected bits of beauty.

I have upgraded the Astrola a bit lately, adding a larger finder ‘scope with a wide field eyepiece. It is a 50mm 3D printed finder of my own design allowing me to see more sky at once with fainter stars.

There are a few more days until the bright Moon crosses into the morning sky, a few more mornings you will likely find me out with the ‘scope.

The Sky for 2017

Looking ahead to 2017 it appears that the skies will be kind to us this coming year. We have good meteor showers, a total eclipse of the Sun, a bright comet or two, and the usual planetary conjunctions to look forward to. Below you will find some on my notes to what we can look forward to during the coming year.

Jupiter 14Apr2016
Jupiter on April 15, 2016, stack of the best 2000 frames of 7600, Celestron NS11GPS at f/20 and Canon 60D
As is my practice I have spent more than a few evenings loading up DarkerView with scheduled posts for the year. Well over a hundred posts are set as reminders for the interesting astronomical events for 2017. It is a useful effort, as I can see for myself what the year will bring and begin my planning.

Covered are elongations for Mercury and Venus, interesting conjunctions, oppositions, eclipses and meteor showers. Posts include notes for visibility in the Hawaiian islands for those events that are location dependent.

Continue reading “The Sky for 2017”

The Sky for 2016

Looking ahead to sharing a fun and pretty 2016 with everyone. As usual you can come to Darker View for heads up on everything happening in the sky for 2016. I have spent the last month setting up pre-scheduled posts with all of the significant sky events for the year. We have a couple interesting eclipses, including a total eclipse across the Pacific, and some nice conjunctions. Comet C/2013 US10 Catalina continues to be naked eye into January and C/2013 X1 PanSTARRS should be marginally naked eye in June.

Young Moon
A very young moon over Waikoloa, this is only 26 hours after new, visible to the unaided eye as a sliver in the fading glow of sunset
Setting up all of the scheduled astronomy posts for the year allows me an excellent overview of what the coming year will bring. As I go though the schedules I have assembled a summary here to give my readers a preview of the year and to allow advance planning.

The Moon

Below are tables of all of the new and full moons of 2016 for those who prefer to plan early for those observing outings. Eclipses are noted with an asterisk in the tables and are explored more fully in the following section.

For those who like supermoons you will have to wait for later in the year when the orbit and lunar phase align. November will be the best supermoon of the year when full moon occurs only two hours away from perigee on the 14th of the month. For a few months either side of the November full moon you will find perigee occurring within a day or two of full, allowing for larger and brighter than average full moons.
Continue reading “The Sky for 2016”

The Sky for 2014

What is happening in the sky this year?

There are no exceptional sky events expected in 2014. A pair of good lunar eclipses, a decent Mars opposition, the usual meteor showers, and no bright comets predicted. There is one odd meteor shower that might provide some fireworks in May mentioned below. Otherwise there is always the possibility of a new discovery, a nova or supernova, or a new comet. For now this looks to be a routine year for sky watchers.

Mars during the 2005 opposition
Mars during the 2005 opposition

Planets

Venus is as always a fun planet to follow through the year. The brilliant morning or evening star is always notable when it passes other bright objects such as the Moon or Jupiter. In April and May Venus will pass both ice giants, Uranus and Neptune with under a degree of separation. In August it will be Jupiter, passing about 35′ away on August 14th. The approach will be even closer if you are able to observe the pair during daylight hours, closing to 12′ at 08:06HST on the 14th.

Mars will pass through opposition on April 8th this year. This is a relatively good viewing opportunity with the red planet appearing just over 15″ in size. Close approach will be a week later, on April 14th. On September 27th Mars will pass about 3° from Antares.

Jupiter and Saturn continue to be well separated in the sky. This results in one or the other being available for observation much of the year. We start with Jupiter in the evening sky until early July. Saturn is currently in the early morning sky, passing through opposition May 10th and available for observation in the evening sky for the latter half of the year.

Minor Planets

The minor planets Ceres and Vesta are quite close all year. So close they will experience opposition in the same week. The dance will take place with the constellation Virgo as the backdrop. 4 Vesta will pass through opposition on April 13th, only two days later 1 Ceres will do the same on the 15th. At the same time the planet Mars will be just a few degrees south of the pair, going through opposition on April 8th. I wonder if the astrologers have noticed this? If so I am sure they will attach some ridiculous speculations to the event. They do not usually pay attention to the minor planets.

Lunar Eclipse 28Aug2007
Total lunar eclipse, photo is a 8sec exposure with a Canon 20Da on a 90mm f/12 APO

Eclipses

There are two solar eclipses and two lunar eclipses for 2014. An odd annular solar eclipse will be visible from Antarctica and Australia on April 29th. A deep partial solar eclipse will be visible across much of western North America on October 23rd. Neither will be visible from the islands.

The two lunar eclipses are more interesting. Both total eclipses will feature good magnitudes and the eclipses will both be visible in their entirety from Hawai’i. Better yet, the first eclipse will begin soon after sunset, providing an excellent viewing opportunity for outreach. Occurring on April 14th and October 7th, these will be the highlight of the year for eclipse aficionados.

Meteor Showers

2014 offers an interesting year for meteor watchers. Of the three most reliable showers it is the Quadrantids that will be seen to best effect in 2014, untroubled by moonlight. The Geminids will be partly obscured, while the Perseids will peak quite close to full Moon.

In addition to the traditional showers there are predictions for a new shower associated with Comet 209P LINEAR. In late May this debris stream may produce a strong, or even storm level meteor shower. Watch here for more information on this possible event.

Comets

While no spectacular comets are predicted for 2014 there are several decent comets available for telescopic observing or photography. Late summer and into early autumn look for comet C/2012 K1 PanSTARRS to peak around magnitude 6.

As usual you should keep tuned to Darker View for timely reminders of upcoming celestial events. Over a hundred posts are already entered and waiting for the appropriate date to pop up here, reminding you and I to keep looking up.