Your data is impressive. How much video data apart from yours in out there? A bigger comparison data set (CCD vs video) might be interesting.

Hi David,

There's a small number of observers using video astrometry and submitting reports to the MPC, although I didn't see any monitoring this flyby. When an object has an apparent sky motion >2"/min Tangra performs motion-fitting and the times of its 'mini-normal' measurements are given to 6 decimal places, e.g.

G2082         n2019 10 26.97675902 04 42.50 +17 20 08.0          12.4 R

The 'n' in column 15 indicates astrometry derived from video mini-normal measurments. I didn't see any other observations in this format during late October.

My user guide can be found here. I need to update it to include the current workflow using OccuRec, but most of the text is still valid.

I wonder how many people have a true video camera with time inserter hooked up to a Hyperstar configuration....

Hi David,

I guess there won't be too many Hyperstar systems used for astrometry. They give a nice wide field and in dark skies can reach good limiting mags, but I wonder if the image scale isn't helpful for astrometry. My C11 working at f/3.3 and Watec 910 video camera gives an image scale of ~1.8 arcsec / pixel. Does the Hyperstar give a flat field across the sensor?

Clear skies,

     Alex.

These are good points. With a small chip you get a very flat, very well illuminated, field about 1deg across. That's what I tend to use most of the time as it suits me. Obviously with the larger sensors, field illumination away from the centre becomes an increasing problem. I'm not sure about field curvature in the outer reaches. David

My setup gives a field of 0.5 degrees across the sensor's diagonal, so as long as that's well collimated and in good focus I can obtain good astrometry from this central zone.

Cheers,

      Alex.