Comet VZ13

by Dennis Beckley

I managed to see Comet VZ13 from the the backyard of my home in Benicia tonight where the limiting magnitude varies between 4.0 to 4.5, depending on which part of the sky you're looking at.

The comet was easily found in Draco about 2.4 degrees N. of mag 3.1 zeta Draco at position angle 22.8 around 10:20. It was pretty obvious in my 10 x 70 mounted Fujinon binoculars but really best seen through my 10 inch dob at 47x and 100x. My first impression was "Man, why does this comet have to be so high up in the sky" (my poor neck).

It's one of those diffuse circular types without any obvious tail. Using the star defocusing method I estimated the magnitude to be around 7.7. Using the distance between two nearby stars I estimated the coma size was somewhere between 6 and 8'. There is a definite central brightening but no stellar nucleus. I'm not good at colors and I saw it mostly as grey. Others have reported a blue coloration.

Mag 13 background stars were seen off and on behind the coma. There were two E-W mag 10 stars just to the S. about 4.7' separation and I could detect westerly movement of the comet over the course of about 30 minutes.

Interestingly, this was the first comet that I've looked at that actually showed improvement using a Lumicon swan filter! I bought this filter from Jack Marling himself during all the comet craziness years ago and I think he told me that if the comet enhances it's supposed to being throwing off hydrogen cyanide gas or some such! Maybe that explains the blue color being reported by others.

I think as the comet continues to brighten it will be a nice object for GSSP and SSP. The close passes by several neat objects (N5981 galaxy trio on 7/11, M102 on 7/14 and M3 on 7/22) should provide many interesting photo opportunities.

Dennis Beckley