Hi all, got the comet last night 25-2-12, the first image is 16x6 minute exposures with astro 40D at ISO 1600 and Takahashi 160mm f3.3 Epsilon Astrograph. I hope Rob or Terry can answer the mystery with the head of the comet, as it appears disjointed. The bottom short piece is actually in the correct position for the comet head, with the longer section showing the rest of the tail to the left of SAO 15007 and SAO 150082. These exposures were taken between 9:18:55 and 10:57:35 p.m. S.A. daylight saving time.
Here are 25x2 minute exposures taken with 5D MK II at ISO 6400 ICNR, and 200mmf2.8 lens. The first is a full FOV showing at the top centre a Very rich blue star, this is Hinds Crimson star. Comet Lovejoy is below centre running cross ways.
Here is a full size crop of the above image, and showing similar to the Takahashi instrument, with the disjointed head. Could this rule out an artifact, as different camera and lens was used. I am new to comet characteristics, and don't know if it would be possible for such to happen, with head/tail becomming detached.
Here are 2 croped images from the 25-2-12 with 200mm f2.8 lens, labels showing the position of Comet Lovejoy, Abell 7 and Hinds Crimson star. The inverted image also shows another nebula area to the right of Abell 7 forming a triangle with Hinds Crimson Star.
Congratulations to Lester Barnes for his image of Comet Lovejoy in April's S&T page 79.
◀ LOVEJOY’S SURPRISE
Lester Barnes
In December 2011, Comet C/2011 W3 (Lovejoy) survived
a perihelion graze roughly 100,000 miles above
the Sun’s visible surface to become a spectacular dawn
object with a bright tail stretching more than 20°.
Details: Canon 20Da DSLR camera with 50-mm lens at
f/3.2. Total exposure was 1 minute at ISO 800. ✦
Thanks Glen. This weather here is a real tease, now with the Moon in the night sky and missed comet Lovejoy passing within 23 arc minutes of Abell 7. I will be still trying for the comet after Full Moon, but with it reaching mag 19 by then, there are no promises.
I hope you can get it Terry with the Moon up. Last time you got it the Moon was up also. If you can get it tonight I may have to pick your brains as to the trick for imaging such faint objects with the Moon in the sky.
No luck, there was too much cloud around. Anyway, its tough imaging such a large extended object in less than perfect skies since any gradient correction you apply can actually remove the object itself. One trick I've tried in the past with some success is to take a couple of frames offset a few degrees from the target to get a good background gradient. I might try this myself when clear skies appear again.
Thanks for the tip Terry, I have learnt a bit about gradient removal in the past few months with all the comet shooting and trying to extract maximum out of every image.
Hi all, last night was my first attempt since the 25-2-12 at comet Lovejoy. The Moon was due to rise at 9:22 and that only gave me about 40 minutes of dark sky to shoot in. Transperancey wasn't the best with some high thin cloud around before sunset. I couldn't count my manditory 30 stars within Orion that is a good test for my area.
The image is 7x4 minute exposures with Takahashi 160mm Epsilon f3.3 Astrograph, and Canon Astro 40D camera at ISO 1600. North it up, and a red "X" is at the ephemeris position of comet Lovejoy. To its left you can see the faint smear of it. I hope Rob will add his handy work to this thread that has brought out the comet further than I was able to.
Tonight looks like it may be clearer and will be a good chance to confirm it. The comet has only moved 15 arc minutes since last night which is only 1/8th FOV of the Astrograph.
Hi all, tonight 12-3-12 the transperancey was slightly better than last night enabling me to bring out the comet better. It even shows up on the standard (not inverted) image. The image is 15x4 minute exposures with Astrograph and astro 40D at ISO 1600. North is at 12 O clock, red "X" is at the ephemeris position and the comet is to the left of that and extends out of the FOV.
Here is my attempt tonight, which required some very agressive gradient correction to tease the comet out of my somewhat light polluted skies. The tail is the streak that heads up to the top of the frame about a 1/3 of the way in from the right . This is a 90 x 60 second exposure with the QHY9 + Hyperstar. The remains of the comet are now 2.16 AU from the sun, its amazing we are still getting it to be honest.
Thanks Terry, good to see your image also. I would have no chance if I had any light pollution to deal with. The extra contrast in your image shows the tail extent well.
...and there is just a chance we might do it all again shortly. Its possible the Comet found a few days ago in SOHO's SWAN instrument might be another Kreutz sungrazer on its way in for a March 16 perihelion! Lets wait and see
...and there is just a chance we might do it all again shortly. Its possible the Comet found a few days ago in SOHO's SWAN instrument might be another Kreutz sungrazer on its way in for a March 16 perihelion! Lets wait and see
Terry
Yes, I read that and thought "here we go again". It's going to be crazy if the SWAN comet is a good as Lovejoy was. We'll see.
If Lovejoy was a small chunk from a bigger comet and then this one is another chunk and then.... oh my god...
Hi Justin, thanks for your comments. The ephemeris lists the magnitude at 19.3 for last night, but I have been informed that, the magnitude is only based on nucleus and corona from figures done back in December. And seeing there is no nucleus or corona the magnitude is anyones guess. Also as magnitude is based on a point source and not a diffuse object it would be hard to work out such on this.
I would be very interested to know also what the magnitude is. It is many times fainter than the Witches Head nebula.
Awesome job Lester & Terry! Incredible to think the tail is still holding together towards mid-March, and discernible at such distance. Here's a little animation I put together of Lester's images from 11 & 12 March. The tail is the horizontal darker bar at left, clearer in his image of last night compared to the night before.
...and there is just a chance we might do it all again shortly. Its possible the Comet found a few days ago in SOHO's SWAN instrument might be another Kreutz sungrazer on its way in for a March 16 perihelion! Lets wait and see
Terry
Looking nice in LASCO C3 images now. Here's a stack of the 18 most recent LASCO C3 images. I just downloaded them from here (click "More 512 x 512" under "LASCO C3") and stacked them on the comet head in Registax. http://sohowww.nascom.nasa.gov/data/...me-images.html
Stacking smears out all the cosmic ray hits and other junk in each of the subs.
Incredible to think the tail is still holding together towards mid-March, and discernible at such distance. Here's a little animation I put together of Lester's images from 11 & 12 March. The tail is the horizontal darker bar at left, clearer in his image of last night compared to the night before.
