The Scruffy Astronomer

  White knuckles It seems that everyone is getting into remote imaging these days. If you have an automated rig in a dome, you don't actually need to be present to make it work. I mean, what's the difference between sitting at a computer two metres from your rig and sitting at a computer 200 kilometres from your rig? The software is the same, the images are the same. You know I'm going to tell you what's different. Security.  Imagine something goes wrong. Suddenly your computer screen goes blank. You don't know if the power has gone out, and if it hasn't, you don't know if your mount is about to mash your expensive camera and filter wheel against the pier. Worse, the dome is open to the elements and there might be a rain storm coming. There's really no alternative but to drag yourself to the car and make a two hour journey out to your remote site. But astrophotographers do it. My state's astronomical society is piloting a couple of locations. A few y...

Nearly nobody reads these blogs, and so I’m going to write one which is pretty much for my own benefit. I normally take notes about my workflow. I rarely actually follow them, normally getting distracted and going off on tangents, but in this case I was so out of my depth (I even needed help from a Dutch expert) I decided to figure it out beforehand, actually follow it, and record it here. Perhaps someone will benefit from the work I've done. Perhaps that person will be me. If you’ve found this blog using Google, and you’re after the actual workflow, scroll down to the section called “processing the data”. Finally, a chance for a photo A couple of weeks ago I visited the ASV’s dark sky site. It was the first time I'd been there for a while (thanks to successive COVID lockdowns) and I was looking forward to taking a decent image. In the time, I’d taken other astrophotographs, but the aim of those was more as a test for equipment, rather than the image itself. No, this was a t...

Finally, an image! I've finally got around to processing an image of NGC1365 - the Great Barred Galaxy - that I got from the ASV's dark sky site in Central Victoria a couple of weekends ago. It isn't the best image I've taken, but it's interesting, and it's my first serious image since before the pandemic! But it was a challenge - I made things hard for myself by using two scopes, two cameras and one very rusty astrophotographer.  Frankenscope! The colour information in the image was gathered in 51 five-minute exposures using a colour camera on a Sidereal Trading modified telescope. This is one crazy machine.  The front half - the objective - of the scope is a saxon 102mm FCD100 triplet, which is a beautiful piece of glass. We removed the somewhat unworthy focuser and replaced it with an Astroworx Crayford focuser made in our own factory. This focuser will soon be launched onto the market, and we hope it will do well. The guide scope was made by Sky-Watcher, t...

Sight, in humans, is quite a popular thing. People regard it highly, and do seem to think it's an overall good idea. My experience of sight has been, like most other people, a given. It started great, and as a kid my family would occasionally use me to find things, like shop signs, in the distance. Of course, it does deteriorate over time, and I've worn glasses since early university. It started just for reading, but soon I was wearing them full-time.  It turned out that apart from being long-sighted, I had astigmatisms which were reasonably severe, and getting worse.  You get old Eventually I wasn't able to look through telescopes any longer: unless I had an eyepiece that I couldn't afford, the eye relief - the required distance between the eyepiece and your eyeball - was so short that I had to remove my glasses. Without glasses, of course, all I could see were comets. No, they weren't meant to be there.  Resignedly, I gave up visual astronomy and went deeper into ...

We've uploaded another video onto the Optics Central YouTube channel. This one is me unboxing the saxon Astroseeker 15075. This is a 6-inch Newtonian on a light computerised alt-azimuth mount. The mount is a nifty little unit, well capable of carrying the weight of the tube. It's a heavier duty mount than the SkyWatcher mini AZGTi, and is capable of taking a heavier tube than the Newtonian here. In fact, this mount is often found with a 127mm Maksutov. The mount can be controlled by the hand controller that's included in the box. Alternatively, because the newest versions of the mount have a built-in WiFi connection, you can also control it using the SynScan app for your phone. The tube is a standard Newtonian, with a parabolic mirror and a focal length of 750mm. This makes it an f/5, meaning it's good for deep-space objects, such as galaxies and nebulas. Star clusters and the Moon are also well within your reach, especially in light polluted areas, but planets wi...

I'm a refractor guy. I've seen these things called Schmidt-Cassegrains, and someone told me they can do astronomy with mirrors. One day I might be beguiled by the hyperbolic surfaces of a Ritchey-Chrétien, or the pure beauty of a well-machined truss tube. For now, though, I reckon that if it was good enough for Galieo, Kepler, Brahe and Copernicus, then it's good enough for me. But refractors have their problems. Chromatic aberration, where the different colours components in the light from stars don't focus at the same point, is the bugbear of the design. Of course, other designs do have their problems. Newtonians have coma, Schmidt-Cassegrains have astigmatism, and Ritchey-Chrétiens have an air of intolerable smugness (with apologies to the late Douglas Adams) So how do we manage chromatic aberration? We have two main ways of controlling the way light changes as it passes into and out of a glass lens. First, the amount the light bends is determined by the ...