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Showing posts from 2019

The wobblings of Betelgeuse

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You’ve probably heard in the mainstream media that there’s a star in Orion that’s gone dim over the last couple of months and might "go supernova". Maybe, but don’t hold your breath. Betelgeuse is a red giant star in the constellation of Orion, one of the shoulders of the Hunter. Of course, in the Southern Hemisphere, we see it "upside down", so Betelgeuse is the lowest bright star in the constellation. Just now, from Southern Australia, Orion is rising in the East after sunset. A red giant is a huge star. If it were transferred to where our sun is, the Earth would be inside the star itself. So would Mars and – nearly – Jupiter. Only large stars can result in supernovas, but this one is plenty big enough. It’s also true that it’s gone suddenly and significantly dimmer over the past few months. Betelgeuse was until recently one of the top 10 brightest stars in the sky. Now it’d struggle to make the top 20 list. However, it's also variable, changing brig

James Baguely's phone images

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30 December 2019 Yes, you can use a phone to get deep sky objects! People often ask me what is the best camera to use for astrophotography. The answer is fairly complex because of factors like setup and cost. But there's a saying that the best equipment is the stuff you reach for first. In this case, that camera is an iPhone 11. James lives in Canberra and recently got himself a telescope - a 10-inch go-to Dobsonian. This scope is actually designed for visual work, but after James was knocked out by what he saw through the scope he decided to try taking photos. He got himself a saxon ScopePix mobile phone adapter and started experimenting. He learned pretty quickly to use the 3-second count-down timer on the phone, and then found that a 10-second exposure in night mode on the iPhone’s native camera app worked best. The fact that it’s a newer model phone helps, as the new ones are much more sensitive to low light. Once set up, the Dobsonian tracks the stars on its ow

Birds at the dark sky site

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27 December 2019 As you probably know, not only am I an amateur astronomer, but I'm also a bird watcher. My wife says I really only have one hobby - expensive optical equipment. While I've talked - at length - about the Astronomical Society of Victoria's dark sky site near Heathcote (Vic) before, there is an aspect of it that I don't think I've mentioned. Without being too specific about the location of the place, it's away from any built-up areas and surrounded by box-ironbark forests. This means birds. The birds there are great. The big problem is hats. If I'm wearing my astronomer's hat I tend not to concentrate on the birds, either because I'm setting up, tearing down, or being otherwise distracted by people or dinner. I spotted this bird on my most recent trip. I initially thought it was a Restless Flycatcher, but on closer inspection it turned out to be a Hooded Robin. While I was photographing him, I also got a rather poorly-li

Belt modification preparation

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25 December 2019 Merry Christmas to all our customers and readers! To everyone who's having a break over Christmas, I hope you all have a relaxing and safe time. To the rest of us, try to keep cool - it's been a hot start to the summer so far. This isn't great for astronomy, for a couple of reasons. First, hot weather makes for poor "seeing", with the atmosphere boiling away, causing light to be dispersed one way then the other, and ruining your view. It's like looking through heat haze, and you can see it in a little sequence I put onto our YouTube channel . The second reason why the hot start to summer isn't good for astronomy is the smoke. It's been a bad bushfire season so far, and looking through smoke haze doesn't make for good views. Incidentally, the heat isn't good for birds either. City birds will do all right, not being far from sprinklers and other water sources. But in the bush, the dryness and heat will really thin the

Summer solstice

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20 December 2019 In my post on the Spring equinox I mentioned it was a pretty sparse time for astronomers. Well, that's over, and the Summer glut of things to catch is here! Start with 47 Tuc, the Pleiades, try the Sculptor Galaxy, then a bit later move to M42, the Great Nebula in Orion, and just go from there. The one I'm waiting for this year is the Rosette Nebula. The Rosette itself might be too dark to see with anything but a large telescope, but it also has a pleasant star cluster in the middle. It's also huge, 1.3 degrees, so you'll need the longest eyepiece you've got. This is suited to a Dobsonian telescope which has a low focal length and wide aperture. Here's the list - as usual I'm giving you the name as well as its rough transit time - the time on the 21st when it's highest in the sky. Some of them don't set. My poor photo is the Horsehead and Flame nebulas in narrowband. Globular cluster: NGC 104 - 47 Tucanae (07:55 PM) G

ASV Star-be-cue

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20 December 2019 ASV Star-be-cue weather forecast is good - well, a lot better than it was a couple of days ago. We've got an updated meteogram for the ASV's dark sky site for tomorrow's Star-be-cue. A few days ago the forecast was for 100% cloud all night. Because of this, some people were considering not coming. But worry not! The cloud is now forecast to be less - certainly enough to do at least some astronomy. Besides, part of the reason for the Star-be-cue is to catch up with fellow astronomers, so my advice is to take the risk. You'll have a great night, even if you don't see as many stars as you might have. I'll be there - a bit late though, as I have to work here until 4pm - so probably after 6, depending on traffic.

Mynas

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I noticed the other day that I have Common Mynas nesting under a loose tile in my roof. Ugh. I’m no fan of Mynas. They're horrible pests and have wreaked havoc on the Australian environment (not as much as humans have, of course), but I can't bring myself to evict them - that'd be a death sentence for the young ones. Damn those principles. When the chicks fledge, I’ll reset the tile and concrete it in, but not before. However, for pure interest, I did spend some time watching and photographing them. I guess that's why it's called "bird watching". The parents are very industrious. They have established a perimeter around the nest. Anything that comes close is heckled and, in some cases, swooped. Mickey, our poor mild-mannered Labrador, gets it constantly. She’s such a sook that one of us has to stand guard while she eats her bones.The parents have also established a feeding routine. This is what they do for the whole day, interrupted only when anyone

Deanne's first light photos

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16 December 2019 This is a first light photo with a difference. First light photos are photos taken with something new. They might be taken with a new scope, or a new camera, or something else. In this case, it was a first photo taken with any telescope. No kidding. But there’s a story. Deanne is already an accomplished photographer, being in the Australian Institute of Professional Photography. She has a number of awards already, and has taken wide field shots using a wide lens. On a visit to Mt Burnett she met Andrew Campbell (of Andy's Astropix) and through him, discovered astrophotography through a telescope. She was hooked, but as with other astrophotographers, Dee found that she had to wait before she was able to afford the equipment she wanted. Finally, however, Dee turned up at the shop and came away with a big saxon 250DS Newtonian and a saxon AZ-EQ6 GT Pro. Dee joined the ASV, and the learning started. After she put the scope up at home and became familiar with

2019 astrophotography contest winners

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16 December 2019 Time to announce the winners of the Optics Central astrophotography competition for 2019! We had lots of entries from some very talented photographers this year, and we had a bit of head scratching to determine who our winners were going to be. But eventually we decided on these two. The winner of the wide field class was Clint Conn of Clint Conn Photography  for his photo of calcarenite reefs taken at Point Roadknight in Anglesea. The winner of the narrow field was David Rolfe's Eta Carina in narrowband. Both are beautiful photos. Congratulations to both winners and thanks to all who contributed. David and Clint, please contact us to arrange your prizes!

Christmas Star-be-cue

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13 December 2019 Christmas Star-be-cue at the ASV's dark sky site, 21-22 December! I'm always spruiking the Astronomical Society of Victoria to people starting out or getting further into astronomy. If you want to see a bit more about what the ASV is about, meet other keen astronomers, see their kit and look through some monster telescopes, then here's your chance. The ASV has a couple of events up at its dark sky site each year, including this big Christmas event. It starts at noon on the 21st and goes all night (obviously). The dark sky site is near Heathcote, about two hours' drive from the CBD. Along with a bunch of other astrophotographers, this is where I take my photos from, so come up and have a look at the place. Places for non-members are NOW FILLED. Of course, if you're an ASV member (like me), then you can just rock up. (I'll be late as I'm working at Optics Central that day.) During the day, there will be solar observing (using a spe

Comet Borisov

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11 December 2019  There’s a comet around, although it’s a bit hard to see. I’m often a bit skeptical when it comes to comets. You hear that there’s one coming, and that astronomers hope it’ll be bright, but so often, particularly in the city, you see a dull fuzzy blob that may just as well be a smear on your lens. So, I’m always trying to manage expectations down, not up. Comet 2I/Borisov approached the solar system from the North, crossing the equator a few months back. Its closest pass to the Earth is on the 28th of December. As to brightness, it's been dim so far, but there’s the possibility of an outbreak of gas as the comet warms close to the Sun. Experts guess it might get as bright as magnitude 15. That’s not bright. You’ll need a big aperture - something like a 10-inch Dobsonian (www.opticscentral.com.au/saxon-10-inch-dobsonian-telescope.html) to see that. The interesting thing about Borisov is that it’s an interstellar comet. In fact, Borisov is only the se

How problems with telescopes lead to solutions

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4 December 2019 I've talked about different types of telescopes before, but I'm having another go - this time with some hand-drawn diagrams that I've scribbled. This blog was originally three Facebook posts, so they haven't really edited together perfectly... Chromatic aberration in refractors It wasn't Galileo who invented the telescope - he just took credit for it. In fact, the refractors we sell in the shop aren't like Galileo's refractor at all - unless you are buying a pair of opera glasses (https://www.opticscentral.com.au/binoculars/opera-theatre-binoculars.html). Galileo's refractor had a single convex lens out the front and a small concave lens for an eyepiece. It showed the image the right way up, but the field of vision was very small - it was like looking through a straw. It was Kepler who replaced the concave lens at the back with a convex lens, lengthening the scope but giving a much bigger field of view. It didn't really matter i

Moon mosaic - with a difference

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2 December 2019 I spotted this photo on the Sky-Watcher Facebook page the other day and immediately realised it was something special. The Moon is everyone's first target. In fact, some people end up specialising in lunar photos, there's just so much detail. What's more, the angle of the light changes constantly, so the views change every night, increasing the fascination. But while a full Moon shows the whole disc, having the light right behind us flattens a lot of the detail. It all really comes out when the light is on an angle. The craters reveal their shadows, highlighting the 3-D effect. Jacob uses a Sky-Watcher 8” go-to Dobsonian (www.opticscentral.com.au/skywatcher-8-go-to-computerised-dobsonian-telescope.html) he got from BinoCentral in Perth. He uses a Nikon D7500 and a 3x Barlow to take lunar photos. The magnification that this gives him means he can't get the whole face of the Moon. Instead, he has to make mosaics, and fit them together on his comput

How to use an intervalometer

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29 November 2019 The cheapest way of taking a photo through a telescope is using a mobile phone, normally stabilised using a phone adapter, such as the saxon ScopePix. This is a good start, but the next step in astrophotography is to use a DSLR. These attach to the business end of your scope using an adapter called a t-ring (this is a photo of mine). But then you've got a whole new set of problems. Every time you press the shutter button, you rock the scope slightly and it ruins the photo. And you want to take lots of photos so you can give them to your stacking software. And you don't want to be hovering over your rig all night, just pressing the button every minute or so. After all, we all need to sleep occasionally. What you need is a way of pressing the button without your having to actually be there. If only there were some gadget that does that for you. Of course there is, it's called an intervalometer, and it’s like an old cable release with a brain. Mo

Ny-Ålesund

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27 November 2019 You probably know that I'm a bit of a Nordophile. I lived in Norway for three years, but sadly never got to visit the archipelago of Svalbard up near the North Pole. This is, you may recall, the location of Brage Bærheim's astroterrestrial photo that I featured a while back. It seems there is a weak point (what that means I'm not sure) in the Earth's magnetic field near Ny-Ålesund, a settlement on the West side of Svalbard. During auroras, the solar wind gets in through this weak point and interacts with the atmosphere, ionising it and drawing some of it out into space along the magnetic field. A while back, scientists at Ny-Ålesund launched two sounding rockets into an aurora. They were able to take readings in a very narrow time period, and gathered data about what they call the "atmospheric fountain". That study is ongoing. However what they do know is that the amount of atmosphere lost into space is only a tiny proportion of th

Southern Hemisphere resources

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Astronomy is a popular pastime the world over. Because of this, there is a pile of information available for people like us to keep up-to-date with what's going on. For an annual guide, the ASV Astronomical Yearbook provides me a pile of information. Being the astrophotographer I'm always looking up rise and set times for the Moon. But there are other very useful and more regularly-updated resources. I get a daily email from EarthSky News, which updates me on anything topical. I also use SpaceWeather.com for solar and aurora updates and Heavens-above.com for satellite information. For maps, my go-to app is Stellarium. This shows me planets, other solar system objects, satellites, deep sky objects and a heap more. However, I was talking with an astronomer the other day, who said she was a bit dismayed at the lack of resources specifically for Southern-hemisphere residents. Most of the stuff we see is mainly for the Northern hemisphere. Because of the different angle, wh

Magnification from a telescope

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One of the most common questions clients ask us is how to get more magnification from a telescope. Just about everything optical these days comes with a zoom lens, so people think nothing of zooming in and out. So how do you do this with a telescope? Short answer: you change the eyepiece. Warning: I’m about to get a bit technical. I’ll use pictures to illustrate, but I won’t be offended if you don’t read on! All telescopes work in the same basic way. The main scope bends light into a focus, and then you use an eyepiece to look at that focus. The main scope might use a lens or a mirror, but the effect is the same – all the light squashed into a focus. The distance between a lens and its focus is called the focal length. The shorter the focal length, the more powerful the lens. Have a look at my little hand-drawn diagram. I’m starting to get a reputation for this .  Magnification of a telescope is given by the focal length of the objective (main) lens or mirror divided by the

Gariwerd hike with Emma

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I’m back in the shop after hiking in the Grampians with my daughter. The Grampians (or as it’s more properly known, Gariwerd) is a great place for a birdwatcher to spend time. We hiked the currently-open section of the Grampians Peaks Trail, a three-day loop that starts and ends in Halls Gap. We spent nights at Bugiga and Borough Huts. When the GPT is complete, it will have 12 campsites. I won’t belabour you with details of the hike itself, apart from saying it was tough in parts but memorable. Views from the western side of the valley were spectacular (as you can see in my phone photo), and it’s rare that you get to stand on the edge of a big cliff. Bugiga was especially cool. It’s a zero-contact eco camp, where you walk and camp entirely on boardwalks. Setting the tent up on a timber deck was a challenge, but our tent doesn’t need pegs, and we were able to fix our guy wires to a cable on the edge of the platform. But the birds were everywhere. Because it’s Spring, they may hav

Joanne Tucker's photos

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18 November 2019 One of the things I especially like writing about is the development of skills in this hobby. More than any other pastime, the demands of astrophotography - precision, care, understanding and patience - create a pathway where beginners develop into skilled users of the equipment. In particular, and I've mentioned this for others before - you don't need to have high-end equipment if your skill level is high. I met Joanne the other day when she came into the shop to upgrade an equatorial mount. She had a Sky-Watcher Star Discovery mount on which she could put either a 127 Maksutov or an Evoguide 50ED scope. This was what she was using for deep sky objects. I was impressed when Joanne told me she was getting photos using a goto alt-az mount, but you remember Josh Carnovale proved it was possible this year. But then she showed me the photos and I was stunned. These are next level stuff. She sent me some, and I said I'd publish three. I've attached

Voyager

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15 November 2019 Voices from interstellar space. Back in 1977, NASA launched the twin probes Voyager 1 and Voyager 2. Voyager 1 left the solar system in August 2012, and now, nearly 18 billion kilometres from the Earth, Voyager 2 has finally left as well. It's outside the "heliosphere", or the bubble of particles ejected from our Sun, and so is now in interstellar space. How can we tell that Voyager 2 has crossed the heliosphere? The probe has a few sensors that are still working. These can measure the temperature, pressure and density of plasma particles blown out of the Sun. Scientists at NASA describe the plasma inside the heliosphere as "solar wind" and the particles outside as the "galactic wind". The characteristics of these winds are different. Voyager 2's measurements all fell significantly in around November 2018, and levels have remained low. This indicates that it wasn't just a random zone of low plasma density, but Voyager

Colour fringing

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Ever wondered how refractor telescopes deal with colour fringing? The other day I pulled apart a telescope lens cell. Here's what I found. Because we service telescopes, occasionally we get patients which are, sadly, unsalvageable. This one was one of those, an entry-level refractor with a terminally mangled focuser. I took the opportunity to pull the front lens off and see how it worked. The telescope is (was?) a doublet-type refractor, meaning there are actually two lenses at the front, built especially to refract blue and red light to the same point. Single lenses refract blue closest to the lens, green in the middle and red furthest away. This is the dreaded "chromatic aberration" that refractors produce. Visually, it's not much of a problem, but taking a photo with this type of lens looks ugly. Check out my photo of the Southern Cross. See the blueish purple fringes around the brighter stars? That's what happens when most of the light is in focus, but th