Comet Holmes
For the last couple of weeks there has been a strange, tailless comet in the constellation Perseus. It started getting more attention in the news when it suddenly brightened, so it’s one of the more popular things in the sky at the moment. Hopefully it will be around for a while; you don’t normally have things that easy to see from the city.
Now, usually I would be whining about how much I hate comets, but this time I was actually able to find it myself, so this one is okay.
Here is a wide-field photo of Holmes, taken with my camera mounted piggyback on my telescope, using a 100mm macro lens:
And, here is a close-up taken through the telescope:
You can see some vibration in the close-up photo. I am pretty sure this was caused by the shutter when I took the photo. Normally I set the mirror to pre-fire, and I take photos on a timer, so I can’t think of anything else that could cause any vibrations.
There is this technique called the “hat trick” (at least, that’s what Michael Covington called it in his great book on astrophotography), which is the simple solution to this problem. Put something large and dark in front of the telescope - say, a hat - start the exposure, then move the hat out of the way. That way there will be absolutely no vibrations during the exposure.