C/2013 US10 (Catalina)
December 1, 2015:
I set the alarm early and drove out to Broemmelsiek Park to see this comet. I arrived at 5:30AM and waited a few minutes, studying the star chart on it first. At 5:40 I tried to find it with 10x50 binos, figuring it was ~6.0 mag and it should be easier to find with a wide field. I was unsuccessful. So, I busted out the 25x100s and found it at 5:47 about 15* up, just above and left of Lambda Virginis. I had vainly hoped to see some tail, but it was mostly just a fuzzy ball, with a fuzzier western edge. A quick check showed the coma to be noticeably bigger than Jupiter, somewhat condensed, but no pseudo-nucleus seen at 25x. With the comet now found, I tried the 10x50s again with no luck still. It just needs to get higher into a darker sky, with less atmosphere to choke it down. A moonless night would have helped too (moon was waning gibbous - 65%, with Last Quarter phase coming up on Thursday).
By 5:55AM twilight was just showing up, and by 6:00AM the comet viewing was done-for. A pretty short window of opportunity. It should be a lot easier to view in the coming weeks, especially around Christmas. It will be up in Bootes by Christmas, and just 1/2* from Arcturus on January 1, becoming circumpolar in mid-January. It will be closest to Earth on Jan 12. Perihelion was November 16, after coming up thru the Southern Hemisphere.
December 4, 2015:
I got up 15 minutes early for my workout and managed to observe the comet from northeast Wentzville MO. The comet was a little 'softer', as the atmosphere that low was less transparent than it was a few days ago, although the zenith looked sharp. Anyway, no suggestion of a tail, or even the beginnings of one (as before). Really just need this comet to get higher in a darker, moonless sky.
A check vs Jupiter confirmed that the coma on this comet was larger than Jupiter's disc. Again, no pseudo-nucleus nor color seen.
I hope to see it soon in 10x50s, and hopefully in a telescope (at a dark sky site) as well. Forecast for the Dec 7 conjunction with Venus (within 4*) is 50% cloudy, rats! It should be in the same 10x50 field of view then.
December 6, 2015:
The weather afforded a window between cloud arms, but I wasn't sure of it when I hit the hay. I woke up around 5am and checked the radar, and it looked very promising. A few more cat-winks and then I got up. I was in a green zone, and the moon continues to wane (20% crescent) so I had hopes of seeing a tail. It took all of about 10 seconds to locate the comet in my 25x100 binos, just left of Venus by a FOV or so. The view was sharp! The coma was round, but had a fuzzy edge on the Western side. It was definitely a teasing view, not definitive. I don't think I could have asked for better conditions.
Just as a hint of twilight appeared at the Eastern edge of the horizon, I grabbed some 10x50s and tried them. Initially no luck, but then I spotted it. Not impressive at 10x and a bit too star-like if hunting for it (not a problem if next to a bright object - like Venus tomorrow?). I reminded myself that this comet's coma is about Jupiter-sized, and thus a real appreciative difference between 10x and 25x. Much easier to estimate magnitude when dimmer stars are in the field of view to compare to when de-focusing.
(Click on either page above or below to enlarge)
I observed a couple of times later, at Wil-Ron in Wentzville. On Dec 16 I was able to spot it fairly easily with just my 10x50s. A clear, moonless sky has helped greatly.
December 19, 2015:
I once again had an opportunity to view this comet from a 'green sky' location. The sky quality was great, and no moon was present. The tail was elusive, but an occasional trace was observed with averted vision. The view was never 'held', and was thus hard to confirm. Later comparisons with photos from the same date do confirm the stronger (ion) tails' direction. Of course, "Westward" would be the most obvious expected tail, so I'm not totally positive that I was not influenced by what I expected to be there.
Other observers have recorded both tails (Ion & Dust) with large binos. The best drawings on CloudyNights appear from scopes 14"-18" in aperture. I hope to get my big scope out some morning very soon, weather-allowing.
One naked-eye star appears in the FOV drawing. CU Virginis is a mag 5.0 variable star.
It won't be long and I should be able to view this comet from my backyard, over the trees.
January 1, 2016:
The forecast was iffy, but I got up at 5:50am and dressed to go check outside. The sky looked great! The clouds have finally lifted. The recent rains and flooding here have not allowed many opportunities to view lately.
The comet was very close (1/2*) to Arcturus. Not visible naked-eye, but the glaring last quarter moon was 'next-door' in Virgo. Catalina was found easily and enjoyed in my 10x50s, but I just had to draw it in the 25x100s. A fleeting and ephemeral tail was seen pointing West, while a suggested other tail was mostly just a strong side of the coma - stub pointing South. I'm expecting to get a telescopic view later this weekend - way overdue.
January 3, 2016:
I finally got clear skies (though not moonless - a waning crescent, 36% lit, was nearby in Virgo) with my 16" dob in a green zone. My expectations were high. I was both very disappointed, and amazed. The 60x field of view was completely filled with the outer coma, although the coma was much more dense on the western side. Within that FOV, there were denser areas that seemed like possible tails, following these past the coma, they were not bright, but I could tell they were there by scanning over from side-to-side. I 'sawed' back and forth for a very long distance (and back - successfully!) on the NNE tail. Probably 4 FOVs (about 5 degrees). It was bittersweet though, as it was about as pretty as some of the so-called "bright" nebulae that I've seen. I regret not seeing this in my dob weeks ago, when it was brighter and farther away (smaller). This view was too "close". I needed 16" of aperture, but only about 30x of magnification. The added contrast would have helped a lot. It might also have been much sweeter with no moon. The forecast is, unfortunately, not looking good for follow-ups on this in the next couple of weeks. This has been a very nice binocular comet, but mostly a temptation on seeing the great tails in photos.