Friday, 27 February 2009

I looked, I saw, I shot

There was a break in the constant greyness that has blanketed the skies for most of the week, It only lasted an hour but I made the most of it.

First off, I setup the 15x70's on my camera tripod, and headed out to try and find this elusive comet that has been around for the past couple of weeks, Comet Lulin. I tried on Saturday, but failed. Anyway, after checking it's position on Heavens Above, I pointed the bins to roughly the right place, and with only a minor sweep, there it was. Excellent and one of those Wow moments.

With my excitement levels rising, I dashed inside, grabbed the HEQ5, carted it out. Plonked it down roughly pointing north, leveled and polar aligned it. I was setup in about 5 minutes, which I reckon is pretty good going, considering it's only my third attempt.

So all setup, mount running, I slewed around, using the clutches, to the right point in the sky, then realised, I hadn't checked my focus... Ah well, Saturn is nearby, thinks I. The ringed one, is a great object for focusing on, as the ring pops out cleanly when focused. So I slewed back, attmpted to line up on what I thought was the star near Lulin I'd been looking at in the bins, and fired a test shot. Hmm, no comet. I used the motor controls to sweep about a bit, and try and find it, but this wasn't helping either. Then it occured to me. The RDF is great, but only for general locating. Given I have my Konus piggybacked (needed for weight balancing) I wondered if it would make a good finder scope. So I grabbed the 17mm Hyperion, popped it in, quickly found the comet and centered it (quite some finder scope a 24x80). Tried a test shot. Hmm, not in the image. I adjusted around a little till I found it, and started shooting 2.5 minute frames. The 3 minute frame was showing signs of trailing.

I set the timer remote to capture 11x2.5 minute subs, and went back to the bins for a longer look. I thought I could clearly see, after studying the comet for a while, that it was changing position relative to the background stars. After watching for a while, I went and had a look at Saturn. Not an easy target at this low power, but the rings could just be made out. I kept glancing round, as a cloud bank was moving in from the north, and I have to say I was very lucky, as the first fingers of it, passed just under Leo and the area I was imaging in. However, it wasn't enough, and I had to stop after only 7 subs.

I then spent a few minutes, adjusting the Konus position, with some card wrapped in duck tape, propped between the OTA and tube rings, to get the collimation a little more accurate, I doubt very much this will be an issue for guiding, as long as I can find a star in the FOV, but as a finder scope, it's more useful, as I can use a diagonal and a decent ep, instead of the camera viewfinder, thus it's much more comfortable (wish I'd thought of that a couple of weeks ago, but that's another story).

Anyway, I cleared up and packed away. Here's a single 2.5 minute sub


The results of the Stack. DSS has a comet mode which I used. It appears to have done a double stack, one for the comet and one for the background stars. Anyway, 7x2.5 minutes, 32.5 minutes @ISO800


And an animation of the 7 frames, which clearly shows the movement of the comet relative to the background stars.


I'm really glad the weather broke and allowed me the opportunity to see and image Lulin, I had feared I was going to miss it altogether.


Haydut said...

Nice one John. Glad you managed to get to see it at last, and managing to image it as well was a bonus.


John said...

Thanks Martin