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C/2012 S1 ISON

Started by John Wunderlin , Jan 15 2013 11:43 PM
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266 replies to this topic

#226 Mike B.

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Posted 18 October 2013 - 07:33 PM

On images C/ISON looks big and health, but what is mostly missing from the images is a scale indicating image size. The nice, bright, seeming "head" of C/ISON on images is little more than a mere 1' in size. For a comet currently just 1.3AU from the Sun this is unusually small. Visual observers are mostly reporting a faint and diffuse outer coma up to 4' in size, but this is very weak.


Yes, I agree. Gauging the size is hard for a little comet like ISON. Here's what I usually do for my comet images:

Posted Image

I looked up the distance between two stars in the image with Cartes du Ceil and created the scale bar based on that. So, it might be off +/- 20 seconds.

#227 Tonk

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Posted 19 October 2013 - 04:10 AM

Mike - you could also post the image to AstroBin (free) or any other online astrometric service and the image is plate solved and dimensions returned to you (or appended to the gallery notes for the image when building your gallery on AstroBin - example here http://www.astrobin.com/33885/ )

#228 Mike B.

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Posted 19 October 2013 - 03:28 PM

Mike - you could also post the image to AstroBin (free) or any other online astrometric service and the image is plate solved and dimensions returned to you (or appended to the gallery notes for the image when building your gallery on AstroBin - example here http://www.astrobin.com/33885/ )


Doh! Yes, you are right. I had already posted it and plate solved it at Astrobin. I could have easily calculated the width in pixels with the data:

RA center: 10:09:51.065
DEC center: +13:57:27.029
Pixel scale: 2.24 arcsec/pixel
Orientation: -178.02 degrees
Field width: 52.31 arcminutes
Field height: 35.15 arcminutes

Live and learn, as they say. heheh :)

Edit: Got it: 268.4 pixels! My bar is a teeny, tiny hair shy of 268. lol

#229 BSJ

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Posted 21 October 2013 - 06:36 AM

"This disintegration will take place before it reaches perihelion,"

http://www.spacedail...ing_up_999.html

#230 BrooksObs

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Posted 21 October 2013 - 08:36 AM

"This disintegration will take place before it reaches perihelion,"

http://www.spacedail...ing_up_999.html


Sadly, just a rehash of misinformation put forth by "staff writers" and one supposed South American "astronomer" with a highly questionable reputation for making predictions that don't pan out.

BrooksObs

#231 TxStars

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Posted 21 October 2013 - 10:11 AM

Perhaps we could still win the comet loto and get a fantastic naked eye view.

#232 Rocky68d

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Posted 21 October 2013 - 02:37 PM

This is indeed a rehash. I found an article from February of this year with these same quotes from Ferrin.

#233 Scanning4Comets

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Posted 24 October 2013 - 03:27 AM

Great pic Mike! :bow:

#234 Mike B.

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Posted 25 October 2013 - 07:11 PM

Great pic Mike! :bow:


Thanks, Markus! :)

Here's one I think everyone will appreciate - a comparison of Comet ISON taken this morning (Oct 25th, 2013) and the image I took 10 days ago on Oct 15th:

Posted Image

I used the exact same equipment and image crop pixel dimensions, so it is a pretty good comparison. What do y'all think? Doubled in size or so?

I was pretty impressed at how much it has grown in the short time since I last devoted a morning to it. Even with a bright moon nearby, it still had considerable signal and it did not get washed-out by moonlight like I thought it might.

Edit: A link to the "final" Oct 25th version is here.

#235 CygnuS

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Posted 25 October 2013 - 09:54 PM

Fantastic Mike!
Thanks so much for sharing these. Great work!

#236 Rich (RLTYS)

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Posted 26 October 2013 - 06:00 AM

Has anyone noticed the ISON's tail has a reddish hue?

Rich (RLTYS)

#237 BrooksObs

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Posted 26 October 2013 - 08:14 AM

Has anyone noticed the ISON's tail has a reddish hue?

Rich (RLTYS)


Of course. It's a dust tail.

BrooksObs

#238 Tonk

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Posted 26 October 2013 - 09:48 AM

Of course. It's a dust tail.


Indeed - Comet Garradd (from a couple years back) also had a noticeable orange-red tint to its tail

#239 canukLX90

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Posted 26 October 2013 - 12:53 PM

Thanks for posting...great images and I do like the
comparison showing how this comet is developing.

PJ

#240 urassner

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Posted 27 October 2013 - 11:46 AM

First attempt at Ison from the City with a DSLR (did not have a remote release, hence the artifact on the brighter star). Animated gif from 13 15 seconds exposures over 9 minutes. Taken through a TV Genesis SDF. It is amazing to me how fast it moves. Had to compress it quite a bit to get it to 200 kb.

Attached Thumbnails

  • 6160699-Ison7.gif

#241 Mike B.

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Posted 28 October 2013 - 10:33 PM

Thanks for posting...great images and I do like the
comparison showing how this comet is developing.


You are most welcome. I love seeing this comet progress and I imaged it everyday since last Thursday until Sunday morning, when weather conditions changed for the worse and put a stop to my efforts.

Sunday's data was only so-so, since the murk was extra thick that day and the moon didn't help matters. It was too noisy to use to make a close-up image. I made the best of the situation by taking the data and making another comparison image, this time with the moon. Check it out:

Posted Image

The moon was taken with the same equipment and is actually a first quarter moon flipped to match the phase of the moon that was out Sunday morning. LoL.

This is the full frame of my imaging rig. I'm hoping that before its all over, ISON won't fit inside the frame because it will get too big! Now that would be awesome. lol

#242 John Wunderlin

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Posted 29 October 2013 - 02:28 PM

Nice one Mike- I think you captured a couple of meteor impacts on the moon as well ;)

#243 Mike B.

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Posted 29 October 2013 - 08:01 PM

Nice one Mike- I think you captured a couple of meteor impacts on the moon as well ;)


LoL. Yeah, its a meteor storm from ISON. (Cue the woo-woo music.) :lol:

#244 CygnuS

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Posted 29 October 2013 - 10:43 PM

Well Mike, when you "make the best of the situation" you sure know what you're doing. It has an awesome 3D look to it. Thanks!

#245 CygnuS

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Posted 01 November 2013 - 03:44 PM

I'm pretty happy to see the Moon fading away. I haven't made an attempt to see the comet since my failed attempt on Oct 15 and I'm excited to try again. Does anybody know what the magnitude increase has been since then?

#246 BrooksObs

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Posted 01 November 2013 - 03:59 PM

I'm pretty happy to see the Moon fading away. I haven't made an attempt to see the comet since my failed attempt on Oct 15 and I'm excited to try again. Does anybody know what the magnitude increase has been since then?


Very little I'm afraid, and mostly due to the comet's decreasing geocentric distance. ISON was reported as a little fainter than 10.0 at mid month and the latest reliable sightings put it in the mid 9's.

BrooksObs

#247 CygnuS

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Posted 01 November 2013 - 07:09 PM

Thanks for the warning Brooks. I suppose it's still worth a try. A half-mag increase might be all I need to pick it up with my 10 inch.

#248 MawkHawk

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Posted 02 November 2013 - 09:09 AM

Mike B, That is a stunning shot!

#249 canukLX90

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Posted 02 November 2013 - 05:33 PM

Image taken on the morning of 28 October. The moon did not
seem to be too much of an issue and the later morning
twilight sure helped in getting more subs as I have to wait
for the comet to climb above 28 deg altitude to clear the
tree tops.

PJ

Attached Thumbnails

  • 6172389-C2012_S1_131028_web.jpg

#250 Mike B.

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Posted 03 November 2013 - 02:32 AM

I shot it on the morning of Nov 2nd, 2013. ISON was rising out the trees and I started shooting it with great expectations that I'd get lots of good data.

Unfortunately, clouds invaded and I had to throw out more than half of what I shot. What was left was lots of LP ridden images and quite a few subs with tree branches in them, since the early subs caught it rising out the trees before the clouds came.

Anyway, you can get the basic idea of how it looked:

Posted Image

ISON seems to be getting bigger but I don't think it is getting any brighter. In fact, since the light is spread out more, it could be even dimming down somewhat.
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