Comet 12P/ Pons Brooks Last night the conditions were good and the comet high enough above the horizon to get a decent view. The blue-grey ion tail is streaming away towards the upper right of the image, driven by the solar wind. There is tremendous structure to be seen here, with the thin streamers near the comet's head which then start to ripple, due to the varying strength of the solar wind, as they move away from the nucleus. The nucleus itself, can be made out as the small bright object at the head of the comet. Off gases glow green to the leftt of the nucleus, where diatomic carbon is excited by UV light from the Sun and emits in the green spectrum. It has a short lifespan and does not persist much away from the nucleus. Meanwhile, the brown curved dust tail can be seen below and right. This is where debris has sloughed off the comet and lies along its curved trajectory. I believe, we are seeing the dust tail, from in front at a narrow angle, which gives it a broad appearance. Although the dust tail is long we are looking along its length which greatly foreshortens it.
The image was produced from 10 x 10 sec images produced through Red, Green & Blue filters to give the colour. The comet moves and that is a problem for image processing. To overcome this the stars and comet in each image were separated with StarXTerminator. The starless comet images were aligned with the comet align tool in PixInsight, such that the Red, Green and Blue images could be separately integrated before being combined to produce a colour, starless image of the comet. Meanwhile the Red, Green & Blue images of the stars were separately integrated and then RGB combined to produce a colour image which was then recombined with the comet using the PixelMath routine. Quite a process but worth it to bring out the tremendous detail in the comet that would escape traditonal photographic techniques. I hope you enjoy this one.