Is that all you've got?
Who's the kook here?
He's talking about AFTER Ison fell apart, and he's documenting that Ison's debris (or the Isonids) has changed course.
And he's not alone in that observation.
From Bruce Gary :
- Dec 11, 21.9 UT: Possible recovery image by Dennis Whitmer on Dec 11, 12:52 UT.
"Blob A" has Rc-mag = 15.91 at a location 10.3 'arc to northeast of the JPL Horizons predicted location.
Please don't get excited by this; we need imaging from tomorrow to confirm or disconfirm the Blob A feature.
I'm postponing writing the In Memoriam web page until this is resolved. (Good work, Dennis!)
2013.12.11 Whitmer R Whitmer observed in a 3x3 mosaic pattern covering ~ 9 times the FOV of his single image FOVs in a search for any kind of blob that could be what's left of the comet. In the upper-left corner location, he had 3 40-second exposures that showed two faint blobs.
Median combine of 3 40-second Rc-band images, made with 14-inch Celestron. FOV = 16.5 x 13.2 'arc, north up, east left. Star next to "A" blob has Rc-mag = 13.71. Faintest stars have Rc-mag = 17.0. Images made between 12:51:23 and 12:53:10 UT, 2013 December 11.
I measure blob A to have Rc-mag = 15.91 ± 0.10, based on 6 APASS stars (with BVr' mag's that I converted to Rc-mag).
Could blob A be a galaxy? No, as the following figure shows.
Same FOV as the previous image, showing no galaxies near the blob A location. The other image is a DSS2 image taken from the SkyMap web site.
Locations of blob A ("DWDec11"), JPL Horizons prediction ("JPL Dec 11"), and a month-old ephemeris (for 2013.12.11, 12:52 UT).
The way to convert JPL Horizons RA/DE coordinates to the blob A location is to add 30.5 RA seconds and add 7.0 DE 'arc.
This may be an artifact of some sort that we don't understand, so the blob A location and the predicted location if it's following the comet track need to be observed carefully, as soon as possible.
If it's clear tomorrow we'll know if this is a "recovery."
One person suggested that there may be a dust cloud of particles larger than typical tail particles and a group of clumps or fragments of larger size.
The dust cloud would be affected by solar light pressure and move away from the sun, while the group of fragments would continue on an orbit unaffected by either light pressure or solar wind.
However, the group of fragments could be on an orbit that was altered when the comet nucleus broke-up hours before perihelion (due to jets and break-up dynamics),
so they could be on a trajectory that is slightly different from what was predicted before perihelion passage.
A bunch of fragments might be very, very faint because they're no longer outgassing, whereas the dust cloud could be visible because of reflected sunlight.
HST is planning observations Dec 18, and they are trying to figure out where to point;
I think they want to aim at the fragment group as a primary goal.
We amateurs should concentrate on imaging the dust cloud because that's probably the only thing that is bright enough to image.
What a comet!
Dec 11, 15.9 UT: I'm preparing an "In Memoriam for Comet ISON" web page which will have a link on this web page probably today.
Dec 10, 23.1 UT: Added a section (above) "My Current Assessment of Comet ISON's Status" in response to several e-mails that assume I know something about comets - which I don't, actually.
Please, everybody, trust NASA, trust CIOC and trust professional astronomers at universities and institutions about Comet ISON.
Some of them may be faulted for over-hyping this comet, but they're not hiding anything
and Comet ISON really did provide a mountain of data that can improve our understanding of comets and formation processes of our solar system. Their assessments will be much more valid than mine!
Dec 10,14.7 UT: Whitmer (14-inch telescope), R-band, dozens of images stacked, show NOTHING at the Comet ISON projected orbit location.
I think the comet is now a dispersed debris cloud that has a "surface brightness" that is too low for detection by standard amateur telescope/CCD observing.
Maybe a prime focus (HyperStar) observation is needed.
Dec 09, 16.8 UT: Whitmer obtained a 3x3 mosaic and found no evidence of a comet.
FOV probably 36 x 31 'arc, limiting magnitude ~ 16.
Dec 06, 23.1 UT: Added image showing my attempt to "recover" the comet after perihelion passage.
It shows that any nucleus or coma must be fainter than V-mag 16.0, provided it was within my FOV.
2013.12.06 Gary V The following image is median combine stack of 20 Cb-band, 10-second exposures.
Median combine of 50 Cb-band images, each 10-second exposure, FOV = 30x21 'arc.
The comet's elevation ranged from 5.7 to 8.4 degrees while the sun ranged from -12.5 to -9.9 degrees.
The animation alternates the 50-image median combine image with a catalog of the same FOV (with the comet in the predicted location).
The faintest stars have V-mag ~ 16, so that's an upper limit on the brightness of any nucleus or coma.
If the comet was within the FOV it would have to be fainter than ~V-mag = 16.0.
Given its "traumatic" disintegration when it was near the sun, and the possibility that only a tiny piece (or pieces) was left, the orbit must have been changed.
Nov 30, 15.3 UT: I'm now ready to declare that Comet ISON is "dying"!
The past 4 months have been fun, sort of, but I'm looking forward to returning to a normal lifestyle.
Whereas comet astronomers are embarrassed by the term "Comet of the Century," they continue to refer to it as a once-in-a-lifetime opportunity to learn about comets.
There will be no more updates on this web page for what I will always remember as the "Dud of the Decade."
