A New Year, a New Night-Time Photography Class!

I’m happy to report that Royal Botanical Gardens has asked me to lead another Night-Time Photography class! If we get sufficient response, we’ll start at 7 PM on the evening of Thursday 26 January 2017, at RBG’s Nature Interpretive Centre. The class will run for a total of four sessions, weekly.

The class will be a hands-on opportunity to take photos at night, with an emphasis on capturing beautiful images of the sky. We’ll cover equipment, celestial objects, post-photography processing, and more. This isn’t an astronomy class per se, but we will talk a bit about astronomy. By the end of the course I am hoping everyone will feel confident going out at night with their cameras and experimenting with capturing beautiful images.

We’ll try to end each two hour classroom experience with a quick dash outside to see be seen. Guidance will also be given on photo opportunities taking place between classes.

RBG’s public program calendar is available on-line at: http://www.rbg.ca/files/pdf/education/publicPrograms/RBGexperiences1116.pdf

You can register on-line for any of the RBG programs at: https://tickets.rbg.ca/PEO/

To find the Night-Time Photography course, just click 26 January 2017 on the calendar on the web site. Registration is limited to 20.

If you are planning to take the course, please contact me ahead of time for more information. It’s recommended that participants bring their digital cameras and tripods to the first class. Digital cameras should be able to be operated completely manually. A wide-angle lens is best for this sort of photography. Tripods should be very sturdy. I can make recommendations if anyone has any questions.

 

 

Consider Being a Citizen Scientist – Amateur Astronomy with a Purpose

There are a lot of different, wonderful reasons to be interested in astronomy. One of the more interesting is that everyone – amateurs anywhere – can actually contribute to science through their hobby. This is not something that is true for many kind of “amateur” activities (those that are done for the love of the thing, not because you’re a professional). Amateurs are sometimes the most interested, creative and knowledgeable people in the fields they’ve chosen. Passion runs high among amateurs, and that’s a wonderful thing.

Recently there was a great example of amateur astronomy brought to my attention. In August a nova appeared in the constellation Delphinus. Given the very straight-forward (if not particularly sexy) name Nova Delphinus 2013, this newly appearing star was discovered on 14 August 2013. At the September 2013 meeting of the Hamilton Amateur Astronomers (http://www.amateurastronomy.org), John Gauvreau, HAA’s Observing Director, presented an overview of what’s known about Nova Del 2013. He pointed out that observers all over the world have been looking at the new star and judging its brightness, using the standard way of expressing the brightness of a star, in apparent magnitude. Magnitude is a sort of reversed scale. The fainter the star, the higher is its magnitude. When Nova Del 2013 was discovered by Koichi Itagaki in Yamagata, Japan on August 14, it was at magnitude 6.8. It reached its peak, about 2 days later, at magnitude 4.3. It then started to fade. By the time I took a photo of the nova on 24 August, it was down to about a magnitude 5.5.

Nova Delphinus 2013, imaged from Ripley, Ontario on 24 August 2013. Ten days after the nova was discovered, it had already faded considerably.

As of this date (14 September, a month after discovery) the nova is being reported at about a magnitude 7.5 – pretty tough to see with the unaided eye, but well within the grasp of binoculars or a small telescope.

The light curve of Nova Del 2013, plotted by the data access facility of the American Association of Variable Star Observers on the morning of 14 September 2013. The curve is a representation of thousands of individual estimates of the brightness of the nova, reported by people around the world.

What’s great fun is that you can contribute to observations of things like the brightness of variable stars. There’s a great organized hub for all of this, the American Association of Variable Star Observers (AAVSO) (http://www.aavso.org). Anyone can learn to judge the brightness of a star (that takes some time, but it’s very doable) either with your own eyes, or with the help of a camera, and then submit your reports to the AAVSO database.

There are other ways of contributing your own observations in astronomy, contributions that mean that your own hobby is more than a past-time, but is really helping science. There are also organized groups of amateur lunar and planetary observers, and even some amateurs that get involved with complex observations like recording stellar spectra. You can also contribute through programs like Galaxy Zoo, where you can help classify hundreds of thousands of photographs, helping observational astronomers chart the cosmos.

Copyright © 2013 David Allan Galbraith

View Nova Delphinus 2013 – A Limited Time Opportunity

Nova Delphinus 2013 (left) and planetary nebula NGC 6905 (right), cropped at full scale from the same photograph taken on the evening of 24 August 2013. While I’m generally pleased with the images I took that evening, there is evidence of some problems on this 30 second exposure – the pulled out stars should all be points. More details follow below.

Although a lot has been made of two comets passing through our skies in 2013, August has given us an unpredictable and much rarer astronomical event: a nova, visible to the naked eye. Nova Delphinus 2013 has proven to be the brightest nova in five yeas – definitely worth a look. Novas are fleeting, however. There isn’t much time.

According to Space.com, Nova Delphinus 2013 was discovered on 14 August 2013 by Koichi Itagaki in Japan. Prior to brightening more than 100,000 times in its explosion, the star was a dim little 17^th magnitude. It became as bright as 4^th magnitude in the days since it was first spotted, and is now fading a bit. Over the coming days and weeks it will fade completely.

I set out on the evening of 24 August from our cottage in Bruce County to see if I could see it. Novas are exploding stars, and the initial flash doesn’t last too long. First, I had to find out the coordinates of this transient object.

The nova is located in the constellation Delphinus, the Dolphin, not too far from the “tip” of another constellation, the arrow, Sagita. The astronomical coordinates are RA. 20 h 23′ 31″, Dec. +20° 46′.

Some near-by land marks help, too:

• Altair (α Aquilae), at 0.9 Magnitude, in Aquila, is the nearest very bright star.
• Sualicin (α Delphini), 3.6 Magnitude, in the held of the dolphin, Delphinus, is the nearest named star.
• A little blue planetary nebula, “The Blue Flash Nebula,” NGC 6905 is so close that it will appear in the same field of view through a wide-angle eyepiece. The 12^th magnitude nebula is located at RA 20h 23m 02.52, Dec+20° 08’57.2″

A wide-angle chart of the area of Nova Delphinus 2013, rendered with the freeware planetarium program Cartes du Ciel. This chart covers about 30° of the sky. The nova and the planetary nebula NGC 6905 are so close together that I’ve just indicated the nebula here.

A narrow-angle drawing of the areas of Nova Delphinus 2013, prepared with Cartes du Ciel. This chart covers about 5°. The nova sits just within the boundaries of the constellation Delphinus (indicated by the faint purple lines).

As it will appear in most telescope mount “go to ” databases, finding NGC 6905 is a great way to get to the area of the nova quickly.

I set out to a gravel parking area near the Bruce Botanical Food Garden on the east side of Ripley, Ontario, at 8:30 PM on the evening of Saturday 24 August 2013 to see if I could spot the nova. I had found this site the night before, and it proved reasonably quiet, and fairly dark, although there are some near-by houses a few hundred yards away.

Some high clouds made the night of the 24^th a little disappointing, and with moonrise set for 9:55 PM I knew I had to work fairly fast. I admit that I had trouble finding the nova with binoculars. I could see a fairly rich star field between Delphinus and Sagita, but really couldn’t decide if I was seeing my target or not.

I reverted to the aid of SynScan on my EQ6Pro mount to save the day, and wasn’t disappointed – eventually. I did found the nova, but only on photographs after the fact. Looking through a 28mm eyepiece on an 8” Newtonian, I couldn’t be sure at all what I was seeing. So, I re-reverted to imaging.

I set up a Nikon D800 body on the telescope, focused on a faint star using live view, and took a series of 30 second exposures at ISO 800. The nova turned out to be the brightest star in the frame, as expected. Actually, I spotted NGC 6905 first! The little blue ball was a charming sight on the photographs, and really stood out. I also have another admission, about NGC 6905. I didn’t know it was in the area of the nova until I saw my photos. At first I thought it was likely an artifact, but a quick check of the area on charts confirmed that in fact it was a planetary nebula, known as the Blue Flash Nebula. NGC 6905 is well worth a look on its own. It’s considered as a very lice planetary, and was discovered by William Herschel in 1782. This was another first for me – my first image of a planetary nebula. An added bonus for a night of nova hunting! The nova itself registered as a bright white star, bright enough to show faint diffraction spikes from the telescope’s secondary mirror spider.

Nova Delphinus 2013 (left) and the Blue Flash Nebula, NGC 6905 (right), photographed on the evening of 24 August 2013 at 9:51 PM EDT, from the east side of Ripley, Ontario. North is approximately toward the left. The single 30 second photograph was taken through a SkyWatcher 8” imaging Newtonian telescope with a coma corrector, and a Nikon D800 body, set to ISO 800, on an EQ6Pro mount. This copy has been reduced down in resolution and cropped from the original frame. The two smaller images at the head of the post are from the same frame, without reduction in resolution.

If weather and conditions permit, I recommend having a look for Nova Delphinus 2013. In the coming nights the moon will be rising later each night, and dropping in brightness, so this is a great time to try, while the nova is still bright. For southern Ontario Delphinus is nice and high in the sky after sunset. No reason not to go have a hunt for a truly rare sight!

Copyright © 2013 David Allan Galbraith

Betelgeuse: A Supergiant To Love

In the evening hours of late winter and early spring in the northern mid-latitudes like Ontario, the constellation Orion is a very familiar friend. The brightest star in Orion, Betelgeuse, is itself endlessly fascinating.

If you can picture the constellation then you can find Betelgeuse right away. It’s the orange-shaded bright star at the “right shoulder” of Orion – or on the left as we see the asterism. The other stars in Orion don’t have a noticeable colour most of the time, but Betelgeuse is decidedly reddish-orange.

Constellation Orion rising over a suburban street in Burlington, Ontario, at about 9:45 PM on the evening of 2013 March 26. Betelgeuse, the brightest star in Orion, is in the middle of the frame and about 1/8th of the way down from the top.

Betelgeuse has been known as an interesting star since antiquity, but what astronomers have learned in the past 20 or more years make it all the more fascinating. For one thing, we don’t know how far away it is too much in the way of accuracy. Betelgeuse is relatively close to earth – somewhere between 400 and 700 light years away, or only about half as far as the Great Nebula in Orion, which we see with our naked eyes as the third “star” in the sword hanging from Orion’s belt. The lack of accuracy is no indication of lack of trying. For stars of this distance, astronomers often use a triangulation method called parallax to work out distances. Betelgeuse is hard to pin down this way because it is not in fact a “point” of light in the sky. The star is so big and so close that it actually has been photographed as a disk by the Hubble Space Telescope in 1995 (Gilliland & Dupree. 1996). It has a complex outer envelope that is changing its size and shape, and makes the parallax method no better than about 1 part in 5 for accuracy. The star is about 640 light years away, but that’s plus & minus 140 light years!

The size of this star is also staggering. Its diameter is approximately the same as the diameter of the orbit of Saturn in our own solar system. It’s also shining about 100,000 times as bright as our own sun. It’s likely a relatively young star compared to our own sun, and some time in the near future (in astronomical terms) it will likely explode as a supernova.

Recent scientific papers on Betelgeuse have gathered together more observations of the star itself and have tried to interpret various areas that look brighter to us as either bright patches on a darker background, or possibly  as bright areas areas showing up through overlaying dark features.

This star is also moving quickly toward a linear “wall” of material that is part of the local stellar environment. Betelgeuse has a shell of glowing material thought to be part of the material blown off of the surface of the star in the past. This shell will hit the wall in about 5,000 years, followed by the star itself about 12,000 years later (Decin et al. 2012). Don’t wait up for it.

Sources

Decin et al. 2012. The enigmatic nature of the circumstellar envelope and bow shock surrounding Betelgeuse as revealed by Herschel. I. Evidence of clumps, multiple arcs, and a linear bar-like structure. Astronomy and Astrophysics 548, A113 (http://www.aanda.org/index.php?option=com_article&access=standard&Itemid=129&url=/articles/aa/full_html/2012/12/aa19792-12/aa19792-12.html).

Gilliland & Dupree. 1996. HST imaging of Betelgeuse. Stellar surface structure: proceedings of the 176th Symposium of the International Astronomical Union, held in Vienna, Austria, October 9-13, 1995. Edited by Klaus G. Strassmeier and Jeffrey L. Linsky. International Astronomical Union. Symposium no. 176, Kluwer Academic Publishers, Dordrecht, p.165 (http://adsabs.harvard.edu/full/1996IAUS..176..165G)

Copyright © 2013 David Allan Galbraith