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C/2013 E2 (Iwamoto)?

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#1 Kevdog

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Posted 16 September 2013 - 10:14 AM

C/2013 E2 (Iwamoto): A morning comet visible in a 6-inch (15 cm) telescope

This is the tagline for Iwamoto from www.cometchasing.skyhound.com

Yet even using the finder's chart and spending an hour tracking down exactly where it should be Saturday night (Sun morning) I couldn't find it. I was using my 18" Obsession with the 30mm ES82 (~70x), then the 18mm ES82 (~110x In case it was too small for the 30mm). I found the stars on the finder chart on either end of where it might be for that night and scanned back and forth to no avail.

Anyone seen Iwamoto?

Thanks!

#2 John_G

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Posted 16 September 2013 - 05:21 PM

I plan on trying for it in October when it's dark enough again but I find Skyhound's estimates can often be optimistic.

#3 Kevdog

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Posted 16 September 2013 - 06:31 PM

I thought the 6" was probably optimistic, but with 9x the light gathering, I thought the 18" would be okay.

Hopefully someone else can confirm or deny being able to find it... at least visually.

My skies aren't the darkest around, but they should be dark enough. Was frustrating not to even see a hint of it. There wasn't even a star out of place on the finder chart.

#4 bleep

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Posted 16 September 2013 - 07:09 PM

I too saw that it was view able in a 6" so I tried looking for it on the 11th with no luck in my AD10. I was in the right area and found the right stars but no comet! I blamed my not being able to see it on the moon. But maybe it's just not bright enough yet?

#5 Jim T

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Posted 16 September 2013 - 08:09 PM

I will admit to striking out on Iwamoto too. I tried on Sept 6. I thought I was on the right star field and cranked to 203x in my 16" Starfinder, no dice. The 40" size estimate may have been a factor, particularly if either that size or the brightness were off. Comets are not dependable!

I did find Comet Lemmon that night, at 60x, and it was pretty darned dim from my green-sky site.
It showed quite a bit of movement over 3 hours at 203x.

#6 Kevdog

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Posted 17 September 2013 - 04:43 AM

I did a search and found a brightness plot from various sightings. It was mag 11-12 at it's brightest and probably more around 15-17 now and fading. So no wonder, it wasn't as bright as I thought!

http://www.aerith.ne...3E2/2013E2.html

#7 Rich (RLTYS)

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Posted 17 September 2013 - 06:25 AM

I personally feel the cometchaseing web site is overly optimistic about comet magnitudes.

Rich (RLTYS)

#8 RenoNV

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Posted 17 September 2013 - 12:50 PM

For comets, you need to get very recent information on location, i.e. JPL Horizons Small Body Browser which will provide the very latest ephemeris and more. Think of a comet as a tumbling rocket, the fancy term is 'nongravitational forces'.

For brightness, there is an estimate made initially that rarely gets updated and almost never in popular astronomy programs, it's used to predict future brightness months later. Recent MPC reports are far better, but one of the gotchas is Total Brightness, which is the same as galactic surface brightness, i.e. it's going to be dimmer. The last brightness in my database for Iwamoto is a 'T' at 15.9, with previous days at 15-16 for the Nucleus. Since the T and N brightness values are so close, I'd say there isn't much of a coma, making it a hard visual object.

Iwamoto has been seen nearly every day for the past month, so Horizons location and MPC brightness reports should successfully guide you. Comets on their way outbound are likely to split and fizzle, and of greater interest for final orbit determination, so they can be a show still.

Overall, nothing is much up since C/2011 L4 faded.

#9 aa6ww

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Posted 23 September 2013 - 12:58 AM

I like using skyhounds site also, but your right, he seems to be in his own world with what he can see with the gear he uses, vs those of us who use or own gear, even in our dark sites.


...Ralph

I plan on trying for it in October when it's dark enough again but I find Skyhound's estimates can often be optimistic.



#10 Tonk

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Posted 25 September 2013 - 12:30 PM

This comet was brightest back in March this year at just around mag 12 - its been dimming ever since so its really a case of being a bit (very!) late to the party in September!

#11 Kevdog

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Posted 26 September 2013 - 06:24 PM

So it looks like skyhound doesn't keep the magnitude and "ability to see" ratings up to date as comets fade? Guess I'll cross reference with other sites like this one to check the current magnitude:
http://www.aerith.ne...t/future-n.html

At least I was happy that I got my first experience at really detailed star hopping!






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