Comet observation from Mars, comets close encounters to Mars in 2013 and 2014 Options

[monitorlizard]

The 20 September 2013 issue of Science (page 1328) has what I hope is an example of sloppy reporting and not a revised estimate of comet 2013 A1 at Mars. The exact quote:

"In late 2014, comet 2013 A1 is expected to barrel into Mars, the kind of spectacle last witnessed when comet Shoemaker-Levy 9 bombarded Jupiter in 1994...comet 2013 A1 should kick up a massive dust cloud for Mangalyaan and MAVEN to feast their sensors on."

The article doesn't quote probabilities of an impact, just states it outright so I suspect it does not reflect current thinking.

[Greenish]

Indeed, that's not consistent with the latest trajectories. The JPL small bodies database browser shows that the uncertainty is now down to 16 minutes in close approach using observations from Sept, and has increased to 5.8 sigma from an impact trajectory. The nominal distance is 134000 km, minimum 66400/max 201000 km (I think these are 3-sigma).

That's some surprisingly dramatic language for Science.

[JohnVV]

For those interested
i posted a "preview" using the ISON and "siding spring" naif kernels
as seen from Gale Crater for both comets

all 3d renderings using Celestia
ISON
https://picasaweb.google.com/10269590129139...NFromGaleCrater

Siding Spring - renderings of the comet( random generated 3d mesh)
https://picasaweb.google.com/10269590129139...ngSpringC2013A1
the rover will have SOME VIEW
-- Comet rise on Oct 19 2014 from Gale


the config files can be found here
http://forum.celestialmatters.org/viewtopi...?f=18&t=578

[scalbers]

I get a magnitude for ISON of about +4.1 seen from Mars at closest approach, assuming +11.5 seen from Earth on Oct 1 2013.

For 2013 A1 "Siding Spring" in October 2014 I get about -7.8 magnitude as seen from Mars.

[jamescanvin]

Looks like Opportunity had a go at taking a navcam image of ISON yestersol (3441). No images available yet though.

[Deimos]

I get magnitude 5.5 from Mars, based on >13 from Earth at this time. And that'll be a bit spread out as seen from Mars. And through dust, for the rovers. Hard to say ISON would be more visible than, say, M31.

Siding Springs will be bright, but spread out--mostly, the surface brightness may not be even visible--except that for it, the nucleus can be detected by things other than HiRise.

I don't know about using Navcam, as opposed to Pancam, from MER. It is not nearly as sensitive, with a bit of neutral density coating.

[Astro0]

Mars Exploration Rover Opportunity - Sol 3441

It'd be nice if ISON were in there somewhere and someone could pull it out.
Lots of noise and cosmic ray strikes to filter through.



Six images:

1P433703396ESFC8MDP2730L1M1 3441 23:37:35 -78.9 330.2
1P433703436ESFC8MDP2730L1M1 3441 23:38:14 -79.0 330.9
1P433703536ESFC8MDP2730L1M1 3441 23:39:52 -79.2 332.7
1P433703576ESFC8MDP2730L1M1 3441 23:40:31 -79.3 333.5
1P433703676ESFC8MDP2730L1M1 3441 23:42:08 -79.4 335.4
1P433703716ESFC8MDP2730L1M1 3441 23:42:47 -79.5 336.2

[Gerald]

This may or may not show ISON:



Subframes have been registered (including rotation 0.2 degrees).
Blur, appropriate stretching, and intersecting for the combined jpg, squeeze out a feature of the three longer-exposed images, that looks a little different from stars (different angle, possible relative motion, less sharp) and noise.
But it's hard to tell, whether it's a significant signal.

[fredk]

I'm sceptical that we're seeing anything. Here's my quick attempt at reducing noise by taking four differences of the three long-exposure frames, registering them, and averaging. Unfortunately the noise is so large that the result doesn't show stars much better than the original frames. Also, I didn't correct for field rotation, so that makes trails look a bit fuzzier away from centre.

Gerald's field is pretty much dead centre in this full frame view. I suspect we're just seeing noise. You'd need the original raw frames to subtract the noise properly.

Can anyone get an accurate position for ISON from planetarium software?

[Gerald]

FredK's image after enhancing the center of the largest object less bright than stars and brighter than background:

Intermediate processing steps here.

[brellis]

Another probably silly question: can one of the orbiters point towards the comet?

[xflare]

what time is closest approach to Mars?

[fredk]

Closest approach for ISON shouldn't matter too much, since it's so far away. It will matter much more for next year's coment.

can one of the orbiters point towards the comet?

They are planning to point. Check out the description I linked to here.

[JohnVV]

what time is closest approach to Mars?

what one
ISON i am not sure
For C/2013 A1( siding spring ) I think it is about 18:30 UT on Oct 19 2014 give or take about 15 min .

[Explorer1]

HiRISE twitter claims that images will be down in the next day or so, and business as usual is going on there.

https://twitter.com/HiRISE