Welcome to Comet Lovejoy! This is a naked-eye comet visible in the northern hemisphere, west of the constellation Orion. My first comet image in some time, and first “proper” comet image, this image depicts Lovejoy as it was on January 9th, 2015. The comet sports a nice tail, one which exhibits a “kink”, warps in the tail that occur periodically. The green coma is common for comets.
For those of you who have followed my blog for a while, you might remember a little over a year ago I was talking about a couple of comets. Back at that time, the comet of the day was ISON, a tailed wanderer of high hopes that sputtered out of existence before it’s brilliant life in the sky really began. About the same time ISON was making waves, there was another comet Lovejoy (Terry Lovejoy is a comet-discovery machine, with a total of 5 comet discoveries under his belt so far!), at the time it was C/2013 R1. ISON was already on it’s approach to the sun, and was visible during twilight just before sunrise, and wasn’t really “imagable.” Some of my prior comet images of C/2013 R1 can be seen here and here. Not all that spectacular back then. 😉 Those were my first days as an “astrophotographer”…pre-tracking equipment…so getting any kind of proper exposure time on a sky object was difficult.
Things are much better today. I was worried for a while that I was not going to have a chance to image this comet with my Atlas mount, which counteracts the rotation of the Earth, allowing me to point my scope and camera at the same place in the sky for an extended period of time. Comet imaging is no simple feat. Despite having tracking equipment, the comet itself is moving on it’s own vector across the sky. That still limits exposure time, and the relative motion of the comet to the stars can actually be observed across individual frames:
This relative motion presents a problem for “stacking” as well. Stacking multiple images of the same thing together with an averaging algorithm reduces noise, making the image cleaner and smoother. For stacking to work, the stars of each individual sub frame must be aligned before the whole stack is integrated (blended together by adding all the images, then dividing the pixel values by the number of images added…simple averaging! :)) Since the comet is moving relative to the stars, that tends to blur the comet. There are star removal techniques that can be used to produce comet-only sub frames, which then allow the alignment to be done just on the comet. The stars of the star-aligned integration are then copied into the comet-aligned integration for a final “proper” comet image.
Well, that isn’t as easy to do as it sounds. In my haste to get some kind of data on this new Lovejoy before the moon rose last night, I underexposed, and that has presented problems for properly generating comet-only images. Thankfully, my exposures were short enough that the comet did not travel too far across the entire set of sub frames, and I was still able to produce a decent image. There is no real structure in the tail, due to the motion of the comet (stacking blurs the comet and it’s tail a bit), but I’m fairly happy that I was able to get anything at all.
Terry Lovejoy’s new find was first discovered back in August of 2014. It was only visible in the southern hemisphere at the time. On December 24th, Christmas Eve, the comet had finally moved north enough that it was finally visible to northern hemispher viewers. At the time it was fainter, low on the horizon to the south. It has risen higher in the sky since then, and now resides a was to the west of the constellation Orion. I first spotted Lovejoy about a week ago, just below the constellation Lepus, which itself is below Orion. As of a night or two ago, Lovejoy is definitely a naked-eye object. At least for darker skies, I confirmed this last night by spotting it with my bare eyes (clearly visible with slightly averted vision, faintly visible with direct vision), then with my binoculars where it was quite bright, even a faint short stub of tail, before finally imaging it. It’s actually fairly bright already, ahead of it’s expected peak in brightness coming somewhere between the 10th – 12th of January.
This comet is taking a path north and west of Orion, past Taurus and the Pleiades (I’d LOVE to get a shot of this near the Pleiades, if I have the opportunity! Hoping the weather cooperates for that! :D) For those who wish to observe this comet on their own, here is it’s path:
I highly recommend using binoculars to view, as the sight is much better with binoculars. I am unsure of how bright the comet will get, I don’t think anyone knows for sure, but it is supposed to brighten a little bit more in the coming days. Comets are unpredictable objects, and it could flare up and become a spectacular naked eye comet, or it could sputter out and disappear into the dark like ISON. Regardless, the next week is probably your best chance to observe it, if your interested.