Monthly Archives: May 2017

To Capture a Globular Cluster

I’ve tried many times to get a good photo of M13, the Hercules Cluster, and this is the best one yet, although it’s done with a telescope that is a bit low in magnification for this object.  M13 is a “globular cluster”, a group of stars that are gravitationally bound to each other.  In this case, there are about 300,000 stars in the cluster, so the goal in photographing it is to be able to distinguish one star from another as much as possible (obviously, we can’t come close to seeing all 300,000), which means getting excellent sharpness. Theoretically, a […]

Astronomy Season has (Finally) Arrived

Over the past week we’ve had some really great weather here in the Pacific Northwest, and I took advantage of the clear skies to start the astronomy season – with astro-photography, of course.  There are some dark-sky star parties going on as a write this, and I didn’t go because there is too much work to do at home, but that didn’t keep me from opening up the observatory and starting some semi-automated captures. The target this time was NGC6888, the Crescent Nebula.  This is a popular target in the Cygnus constellation, and is often photographed, both in natural color […]

You Don’t Always Get What You Want

We had some clear skies here for a few days, and although I’ve been too busy to stay up all night for deep-space object (DSO) photography, I had been waiting for the opportunity to try planetary imaging with the ASI174 camera I got a few months ago, and there was a transit of Io across Jupiter happening that night.  I didn’t get it. Here’s what happened:  The picture above was taken well before the transit started (I think the dim spot just to the left of Jupiter is Io) with the camera attached directly to my 8″ EdgeHD telescope.  This […]

PerfectStar Goes Bipolar

In this case “bipolar” does not refer to a disorder, but to a type of motor.  The current version of PerfectStar, like most focus controllers, uses “unipolar” stepper motors.  The indirect reason for this is that I (and probably most of my competitors) designed the controller to be compatible with existing motors (and for the motor to be compatible with other controllers) despite some significant advantages of bipolar motors over unipolar.  I’ll provide more details on that later, but first, I want to point out some other changes. In the above photo we see the “front” end of the controller. […]