Comet Johnson

Just got done with the processing of some subs I took of comet C/2015 V2 Johnson on March 3rd.  The fact that the comet was so close to the bright star Tau Herculis (mag 3.9) made it really difficult to get the image processed.  It's not great, but it is in there; green and all! 

C/2015 V2 (Johnson)
March 3, 2017
EdgeHD11 Telescope at f/7   40x180sec subs

Why green?  Many comets have an abundance of chemical compounds such as cyanide (CN₂) and carbon (C₂). When these compounds are ionized, due to the sun's energy, they emit light in the green spectrum.  Hydrogen (more common) also glows but is much fainter. 

Johnson's orbit really favors us northerners as she will be high in the NE - E over the entire time.  The chart shows Johnson on March 18, 2017 at midnight, with the future positions marked in red.  Note however, that every day the comet actually gets higher and higher due to the earth's rotation and the fact that the comet is following a rather straight path to the west.  It is about 37 degrees up from the eastern horizon right now, but by May 15th she'll be directly overhead at midnight.  So by then you could see the comet the same as now in March but at 9:00PM rather than midnight.

C/2015 V2 (Johnson) is a hyperbolic comet discovered on 3 November 2015 by Jess Johnson (Catalina Sky Survey) at an apparent magnitude of 17.1 using a 0.68-meter (27 in) Schmidt–Cassegrain telescope (Wikipedia).  Since the orbit is hyperbolic, Johnson will not return to our solar system, but after passage later this summer she will head out to deep space.

I'll be imaging Johnson whenever I can.  By June she may even be visible to the naked eye in dark skies.  Certainly visible with binoculars.