On Jul 23, 2020, at 9:32 PM, Roland Christen via groups.io <chris1011@...> wrote:

https://www.astrobin.com/full/xjomop/0/

Imaged with the 160EDF refractor on the Mach2 mount. The comet head was tracked using the Keypad Drift Model. I took one data point on the comet's nucleus (a 4 minute drift measurement), then turned on the Model to begin tracking the comet. I took a total of 40 images of 30 sec each thru LRGB filters over a period of about 1/2 hour until the comet dropped below my observatory walls. The background stars moved approximately 1/2 way across the frame during that time while the comet stayed stationary on the chip. Seeing was good but transparency was unfortunately poor with thin high clouds.

Tracking comets can be done two ways, with APCC Horizons and now with the keypad custom model. Using Horizons with emphemeris data takes a bit of doing, and is suited for permanent setups. The keypad drift model is very quick and quite accurate and can be done in a field setup in just minutes.

Roland