I’ve been amassing the components of my astrophotography rig over time. Before Christmas I got hold of a guide scope and I attempted to rig up a modified webcam as a guide camera. This wasn’t too successful so recently I bought a dedicated but inexpensive guide camera. After a brief experiment in my back garden to make sure it worked OK, I headed out to my favourite spot in Somerset.
This was the first attempt at using the guide camera and also at using a laptop to control guiding and exposure using PHD Guiding and BackyardEOS. Previously, without guiding, I was able to expose for about 45 seconds before tracking errors became apparent. With the guider, I managed a 5-minute exposure without any visible tracking errors.
This is a single frame depicting M1, the Crab nebula. Exposure of 5 minutes at ISO 6400 using a 6″ f/5 Newtonian telescope. As it’s a single frame, the noise is quite bad. M1 was in an area of sky over Bristol, quite badly light-polluted so the background was quite pale. I stretched the contrast to make it appear black again. The focus isn’t quite spot-on, either.
The laptop I’m using for this is old and not very powerful, but I chose it because it’s small, light and frugal with its power consumption – which is useful when all the equipment is running from the car battery. However, it didn’t quite have the grunt and the processor was running at 100% the entire time. It worked, but was frustrating to use. Next time I’ll just take a normal laptop and keep an eye on the car battery voltage, in case I get stranded.
Anyway, having proved that the equipment was functioning and that my technique was at least acceptable, I set about taking some “proper” exposures to form part of a stack later on. At this point, the silence of the night was pierced by a squealing sound. I investigated, and found the source to be the laptop’s 12V power supply. As I looked at it, it made a loud pop and the magic smoke escaped. Clearly it wasn’t capable of supplying enough power. The laptop’s battery was at only 7% and obviously hadn’t been charging for a while. It lasted another couple of minutes, and then ran out – leaving me with no guiding or automatic exposure.
So that’s another astronomical outing where I came home almost empty-handed (without a proper picture to show for it, anyway) but at least I learnt some important lessons. Hopefully next time there will be some picture of some of the dimmer Messier objects that I haven’t been able to photograph in the past.
Jonathan Gazeley 