More evidence that the comet is rotating or spinning around an axis. This is just over 3 hrs of time and the angle of rotation in that time looks to be about 5 degrees. So, if we take 360 degrees and divide by 5 degrees we get 72, which is how many 3 hr periods to total one rotation. 72 times 3 hrs = 216 hours total time for 1 rotation. 216 divided by 24 hrs = 9 days. Bingo!
This image should correspond to my image from Jan 16th, 2015 (UT.) The resemblance is striking, especially the head area. However, it does look like this one has just a little less width and therefore is turned at slightly more of an angle than the one from Jan 16th.
Well, well… the comet is spinning. Possible revolution of about 9 days. Then, the same features should show up again and again in a repeating pattern every 9 days. Well, let’s take a look, then:
If we go back in time 9 days to January 10th, 2015 UT, images of the comet should look similar to the 1st image in my animation. So, I went to Spaceweather’s Comet Gallery and found these images from the day in question. Here is a partial list:
Taken by Gianni Cerrato (xamad)
There you go. Almost exact matches. The comet changes but it also doesn’t. It repeats a pattern because it is rotating. We see the same tail structures every 9 days, at least in this part of the apparition. On Tuesday, Jan 27th, 2015 CST (Wed Jan 28th, UT, ) the comet should present the same structures again as in my 1st image.
Unfortunately, the Moon will be just past 1st quarter and just to the southeast of Comet Lovejoy, so getting enough detail of the dim tail features will be difficult. I might try my Lumicon Deep Sky filter on it with the Canon 200mm F/2.8 telephoto to see if that blocks some of the moonlight.
The last image I took of Comet Lovejoy before the weather changed and it clouded up and rained. There is a moon out now and the window to image Comet Lovejoy will get smaller and smaller as the rest of the month progresses.
The Canon kit lens that came with my camera sat unused for so long, I figured I should at least test it a bit for astro use. This is the second time I used it. But, no matter how hard I tried, the focus was never very good and I had to repair the misshapen stars in Photoshop.
Continuing to track the evolving tail structure of Comet Lovejoy Q2. Compare it to the image from the previous night and you might notice that it rotated into a “flatter” configuration with respect to the Earth instead of the tail actually changing shape that drastically.
Here’s the best image so far from my efforts to image C/2015 Q2 (Lovejoy). I was shooting it simultaneously with a 200mm telephoto that was mounted above the Televue TV-85 APO imaging refractor.
On Sunday, January 18, 2015, the skies were finally crystal clear. I used a 18-55mm Canon kit lens and shot Lovejoy Q2 with it. Not exactly the image scale I wanted, but I needed to test that lens anyway, since I’ve never used it before.
I did not have an LP filter for this and it shows. I went 2 minutes at F/5.6 and it was almost too much. With the Lumicon or IDAS filters I own, I could go 5 to 8 minutes easily.
Update: Improved Image
Here’s the shot I wanted to get the other day, but I missed it. On this night, I devoted more time to imaging with the 200mm telephoto than I did the TV-85, because I really wanted to see it with the telephoto. Unfortunately, my Bogen ball-head camera mount did not hold well with the camera oriented in a portrait mode to get the full length of the comet. I had to orient it landscape and that cut some of the tail off. But, at least I got a good portion of it with this arrangement.
Clouds and fog hindered my imaging session for the evening of Jan 16, 2015 (CST.) I had to throw out lots of sub-images for this and the stack ended up with a lot of noise because some subs with clouds got in regardless of my efforts.
