Showing posts from September, 2019

Tawny Frogmouths

Frogmouths have nested at my local park for as long as I have lived here. There are a few nest sites, all in Ironbarks, and normally close to the creek. Only one site is not near the creek, and I suspect this is only used when the population is high and nesting sites are hard to come by. The nests themselves are flimsy; a handful of sticks placed across a horizontal fork in the branch. The fork has to be fairly close to the trunk. Frogmouths are famous for their camouflage. They really do look like stumps, especially when they adopt that head-up pose. The local pair lost their previous site a few months back when the branch broke off in a storm. I haven’t seen the new nest yet. I have seen an adult on several nights, so it must be close. People think Frogmouths are owls, because they’re active at night. They’re actually nightjars. Owls are genuine raptors who catch their prey in their talons. Nightjars use only their beaks to catch prey. If you have a close look at a frogmouth,

Southern hemisphere equinox

A few days ago was the equinox - vernal or autumnal, depending on where you are on the globe. Day and night are pretty much equal in length. My parents have some friends living in Boston in the US. These friends noticed thiscartoon in the Boston Sunday Globe on the 22nd. It's about right. Because sunshine just grazes both the North Pole and the South Pole at the time of an equinox, everyone on the Earth's surface gets a bit of sunshine on that day (barring those tucked behind mountains, in holes, wearing sunglasses, and so on). Please don't troll me. Of course, all these things are "more or less", because of any number of factors. Probably the most important one is the precession (yes, that's spelled right) of the equinoxes. This happens because the Earth's axis of rotation also rotates - imagine a spinning top slowing down. It starts to wobble, but the direction it droops towards rotates around slowly - much slower than the top itself is spinni

Where on earth is Procyon? Sky alignments for your go-to mount

Go-to mounts are great Many of our Sky-Watcher or saxon telescopes come on computerised mounts. These are great, and allow you to quickly find stars, planets and other targets without having to slog your way through star maps. But they need to be aligned For go-to slewing to work, you have to align the mount to the sky when you set up the scope.  Sky alignment allows your mount to know which way it is pointing. Telescopes, like planes and boats, change directions in three ways: pitch (up and down), roll (twisting clockwise or anticlockwise) and yaw (left and right). Roll, for an alt-azimuth mount, such as a Sky-Watcher Star Discovery or a saxon AstroSeeker, really isn't much of a problem. This is because your mount should be close to level, and you're not going to move it anyway. To set pitch (known in astronomy as altitude ) and yaw (known as azimuth ), though, you're going to have to show it some stars before it can take over. There are a number of different

Spring equinox

The Spring Equinox might be great for bird watchers, but it’s pretty slim pickings for astronomers. The list of things to look for isn’t as long as at other times of the year. Not that there’s nothing to see, of course! Here’s my list of springtime objects. Remember, new Moon is the best time for seeing the dimmer targets such as the nebulas. Remember also that the size of the target will determine how well you’ll see it in any particular scope. Sometimes magnification isn’t your friend! The list is ordered by the time targets pass the meridian – that is, their highest point of the night. So the Omega Nebula is starting to set after 6:45pm, so look for that one first. Also, depending where you live, some of these targets are “circumpolar”, meaning they don’t set at all. To this list you can add a number of summer objects, as Orion is rising in the early morning even now.  I’ve already seen a few photos of the Orion and Horsehead nebulas published by keen astronomers. This pic

Great Nebula in Orion

M42, the Orion Nebula, or simply the Great Nebula. This is probably the most famous of all the Deep Sky Objects, partly because it's so bright, and partly because it's near the equator and so can be seen by nearly the whole planet. It's also, I think, the most photographed object in the sky after the Moon. It's everyone's first nebula, and for good reason. This one is one of my early goes using a DSLR, which I still think was pretty good. Orion is imagined as a hunter having a belt of three stars, from which hangs a sword of thee stars. In the Southern Hemisphere, of course, he's standing on his head, so the sword is above the belt. Here's a Stellarium map. In the Southern Hemisphere, the pattern is sometimes known as "the saucepan", so for "belt and sword", read "base and handle". The Nebula itself is easy to find. Round Christmas, find the "belt" stars, and then find the three sword stars. Now look carefully a

Lunar 100 challenge

The Lunar 100 challenge – are you up to it? The detailed study of the Moon is called Selenology, and you can do it with a beginner scope. With nearly no exception, beginner astronomers start by looking at the Moon. After all, it’s the obvious thing, hanging there in the sky looking back at you. But after watching the Moon for a few nights, lots of people decide it’s time to move on, and begin looking for new sights. What else is up there? But hang on – why look beyond the Moon in the first place? The Moon, unlike nearly everything else in the sky (even planets), changes on a daily basis. Several years ago, Sky and Telescope ran an article listing 100 things to see about or on the Moon. The list is here , and starts - somewhat obviously - with L1 “the Moon”, and moves to L2 "Earthshine" (see my photo), before getting more and more detailed. The list was created as a bit of a challenge, and has re-engaged many astronomers with our nearest neighbour. The Moon is brig

Eagle Nebula without stars

I'm always trying to find better ways of processing my images. Like others, I'm never satisfied. I love the backgrounds that narrowband filters give me. The swirly, mysterious clouds that you find in nebulas, combined with false colour that highlights the different elements can produce the most spectacular and aesthetic images. The problem is that the stars you find in these images are awful. It's well known that narrowband stars have a purple tinge that makes them look wrong. If you look closely at the first of these images you'll probably see what I'm talking about. Yuck. If only I could get the beautiful false colour backgrounds along with visible colour stars. Well, recently I've found a way of getting just this. Out in the field, I have to collect data for two images - a false colour image using narrowband filters, and a true colour image using red, green and blue filters. Back at home, I process the narrowband filters to get a nice background,

Josh Carnovale's Lagoon and Trifid Nebulas

You might think this wide field shot of the Lagoon and Trifid together is pretty reasonable, but when you find out it was taken with a saxon 70mm travel scope, it raises it to a remarkable achievement. Josh is a year 10 student at Charles Latrobe in Macleod, which has a STEM focus, including an astronomy club. Josh has been taking Milky Way photos with a 50mm lens, but decided to get into narrower field astrophotography. His brother recently upgraded his 10" Dobsonian by attaching tube rings and putting it on an NEQ6 mount. Josh wanted to get to know the new mount before putting a large scope on it. The family happened to have the travel scope, so Josh attached a Canon 1200D and put it on the mount. Using this, he found that he wasn’t able to track stars for more than 25 seconds before they started to turn into spaghetti. Josh realised he needed better polar alignment, so he came into the shop. We talked about the polar alignment routine that I’d demonstrated on our YouTube

Magpie season (and some other garden birds)

Yes, it’s definitely spring. Adult birds are busy preparing to make baby birds. This involves a lot of calling and a good amount of flying about carrying nesting material. But mostly, it involves chasing. Yesterday evening, my local Pied Currawongs caught my attention. They were out in my Camphor Laurel tree, calling their little hearts out. I used my phone to record their calls. However, they weren’t the only birds active in the area. It seems that Currawongs chase Little Ravens. A lot. Perhaps the locals have had problems with Ravens raiding their nests, or perhaps Pied Currawongs just find Ravens a threat. Either way, whenever a Little Raven came past, the Currawongs would make sure it kept going. That wasn’t the only chase. Noisy Miners will chase just about anything. They’re like a dog chasing a car, in that if there’s only one, they chase aggressively but they don’t really seem to know what to do when they get close enough to make contact. Noisy Miners’ strategy seems to be

Leicas at Goschen

The other day, I visited Goschen, a small reserve about 15km west of Lake Boga in North Western Victoria. It's near a ridiculously tall communication antenna. Some Crimson Chats had been reported there recently, and while I had seen one before, I wanted a decent photo, and besides, I hadn't seen my birding mates for a while. Our party totalled four, and they're much better birders than I am. Paul and Ruth are the current record-holders for birds seen in one year in Victoria. But Paul and Ruth didn't have the Crimson Chat on their Victorian list, and so they were keen to go. So at 4am I was up and setting off (astronomers and birdwatchers get used to sleepless nights). The trip from Melbourne is a shade under four hours, so we had plenty of time to talk. To my surprise. everyone else owns Leica binoculars - more evidence of the seriousness of these birders. Paul uses Trinovid 8x42, and Ruth has Trinovid 10x32, which are lighter. Alan has the wonderful Ultravid 8x