Three weeks ago, Comet Holmes underwent an unexpected spectacular outburst that some have misnamed an "exploding comet." This outburst beginning October 24 initially vauilted brightness from 14th magnitude (about as brignt as Pluto!) to about 7th magnitude (almost visible with the naked eye). Most astronomers predicted that the gas ejected during this outburst would gradually disperse and fade. Surprisingly, the comet has grown even brighter almost every day. On the night of these photos, the comet was a bright 2nd magnitude in the constellation Perseus, clearly visible with the naked eye as a fuzzy star. In binoculars or small telescopes, it seems to explode into a bright hazy ball, half the size of the full moon! You've gotta see it for yourself,.as the comet coasts about 100 million miles from Earth, beyond the orbit of Mars. The tail of the comet is barely visible, because it is so faint compared to the rest of the comet, and hidden by the glow around the core. You can see a faint tail in the overexposed images on the right and below. .
The image above combined 27 2-minute Luminance exposures with 9 2-minute exposures each with red, green and blue filters, for a total imaging time of almost 2 hours. An ST2000XM camera was used through a TEC 140 refractor at the Hidden Lake Observatory Because the comet is moving slowly against the background sky, I had to process the star image separately from the comet image, and then merge the two.
The image on the right was overexposed to show the faint blue ion tail. I used the same ST2000XM camera through a Takahashi Sky90 refractor with a reducer, to give less magnification with a wider field of view. I over exposed the core with 10-minute sub-exposures, binned 3x3, including 4 blue and one each red and green, for a total imaging time of one hour.
The image below was taken with the same setup, but 10-minute subexposures binned 2x2, including 9 blue and green and 5 red, for a total imaging time of almost 4 hours.
