This past weekend I was planning to image a galaxy known as the Southern Pinwheel. Everything was perfect: The weather was cold and dry, the galaxy was nice and high in the sky, and it was a good dark night. I spent a bit of time with my trusty Deep Sky Hunters atlas, Stellarium and Cartes du Ciel planning my route to find the thing. I set up the scope in the afternoon so that I would have plenty light to work by, and set up the camera. I pointed the scope at a distant water tower, just peeking over the horizon, and used that to align the finder and find focus. I pointed up at the zenith and snapped twenty images of the fading sky for later use as flats. And then I covered it all up and went inside to help my wife out with the kids. Everything was ready for a perfect evening’s stargazing and photography. Or so it seemed…See, one of my darkest failings is that I don’t actually get out under the skies as often as I want. When I do get the chance, I feel so pressured to get it over with that I end up just touring the same old favourite few objects before packing up again. I write authoritatively about the subject, I’ve even managed to become the director of ASSA’s astrophotography section, but the truth of the matter is that I’ve gotten rusty at basic observing skills. So after I’d powered up the camera and drive, and hooked up the laptop, I pointed the telescope at the 3rd magnitude Pi Hydrae, and got ready to star-hop to my destination. That’s when the trouble started.
Star-hopping is very simple, in concept. It’s a way of navigating the stars, following a series of landmarks until you are looking at the object you were looking for. Telescopes have very narrow fields of view, and most of the objects we want to look at are too faint to see with the naked eye, so to actually find the object and get the telescope pointing at it is a technical and complex task. These days, of course, sophisticated electronic mounts are included on even many entry level telescopes that do all the work for you, but my telescope comes from a time when such systems were horribly expensive and not even that accurate. So I have to do it all manually, and the process works a lot like how we used to navigate before GPS was invented: Open out a map, find your starting point and your destination, and work out a route. Then start writing down a list of instructions – turn left onto this highway, turn right at that junction, head on straight for 55km, and so on. Except with stars.
So what we do is open our star chart up, find start and destination, and then figure out a route between them. The route is a series of hops, from star to star. Each star on the way is chosen to be something that’s part of a recognizable pattern (so that you can find it), and each hop is chosen to be smaller than the field of view of the finder scope (so that you don’t have to hop so far that you wander off course and get lost). It really helps to have some sort of template to place over the map showing the size of the view through the finder’s eyepiece, because then you know for sure that your view matches what’s on the map, and that it’s safe to move on to the next hop. But apart from that, it’s easy. No sweat. Do it in my sleep.
Now in real life, you run into a few problems. First, the view through the telescope is generally upside down, mirrored, or both, so immediately you have to mentally reverse all the directions. Map says go left and up a bit? You want to go down and right a bit. Or was it down and up a bit? Then you find that your lovely crisp map with all those beautiful tiny stars printed in stunning detail doesn’t work so well in the dark. The stars are invisible. You need a light, but then your night vision goes and you can’t see anything in the sky! And finally, you need to be an acrobat to use a telescope. It’s pretty much a given that, no matter what you want to look at, the telescope will point in such a way that the you have to bend down to half height, and turn your head through 180 degrees to squint through the eyepiece. And then you have to hold that position while using one hand to shift the telescope and the other to tighten the locking screws. And you have to do all this while dressed like the Michelin Man because good viewing evenings are usually very cold.
So there I am. It’s about 11pm, my muscles are shrieking in protest at the gymnastics I’m putting them through, and I’m muttering the filthiest curse words I know because, for the twelfth time in a row, I have gotten lost on the star-hop. I’ve made my life easier by switching to an electronic starchart which flips and rotates the view to match what I’m seeing, and it has an ‘eyepiece’ mode, which replicates the view through the eyepiece exactly, solving two of the problems above. I’m starting to finally get the hang of this, but the pressure is building. Once I’ve acquired the target, there’s still at least an hour of image acquisition to go before I’ve collected enough light frames and calibration images to create a beautiful image, and I have work the next day. So I return to the start, and start the hop again. And again. And again. Several times I’ve thought I might be on target and just fired off a 30 second test exposure at maximum ISO sensitivity, using the camera to see if I’m actually on target, but returned only an ugly picture of residual skyglow and lots of stars.
But I know I’m getting closer. Each time, as those stars on my route burn a little deeper into my memory, the star-hopping goes a little faster, and I get lost closer and closer to the destination. And then, at 11:30pm, the camera goes “click”. All by itself, without me touching it. I stand, work the latest crick out of my neck and bend to look at the display: “Change Battery”.
I only have one battery for the camera, and one battery in the telescope drive. The laptop is pretty amazing, it was still reporting 5 hours power left, but the camera was now dead. The evening was at an end, with nothing to show for it but twenty useless flat frames. It was not a successful evening. Frustrating, cold, wasted, and curiously motivating, but not successful. The entire rig is still out there, under its cover, with just the camera packed away, so that the next available evening, I can pick up where I left off. The laptop hasn’t even been shut down – the charts are still open, still in dark-sky mode, still waiting for me to finish the job. And I will. But now I have a new project: Get some electricity out to the pier, with adaptors for the mount (needs 12V, no clue what the current requirements are), and the camera (also, unclear since Canon don’t make this information easy to find). And from now on, I run from mains. But I do wonder what to do about power when I’m away from home. Internal batteries are clearly not up to the job, if they die before I’ve even found my target. Suggestions? Say something in the comments – I’d love to hear some ideas.