## Archive for March, 2013

## Histogram of close approach distances

The histogram shows the distribution of close approach distances to Mars, based on recent calculations. The column width is equal to the radius of Mars. “Red zone” – collision with planet, orange – the number of virtual particles into the Roche limit, which was calculated for comets.

## Probability of collision with Mars – 0.08%

Initially the calculation was based on the recent observations known for me, including observations by ISON-NM observatory (Feb. 27), Martin Mašek (Feb. 27) and Tomas Vorobjov (March 1). Estimation was made on a sample of 1,000 virtual particles (clones), calculated by the Monte-Carlo method and based on the nominal orbit solution. Calculation shown what only 2 of 1,000 clones will collide with Mars, i.e. 0.2%.

Late at night, we received information what found two another archival observations (October 4, 2012) by Pan-STARRS. Now, arc of observations increased to 148 days! Based on the new data, calculations was restarted again. The collision probability decreased in 2.5 times. Neither clone from a sample of 1,000 virtual particles not collided with Mars. Final calculation is based on a sample of 10,000 clones! It shown that only 8 virtual objects will be collide with the Red Planet, i.e. probability of this event fell from 0.2% to 0.08%, but still high enough for the events of such scale. Minimal distance of close approach, according nominal orbit solution is 0.00039 AU or ~58,000 km.

## Close approach to Mars. Up-to-date analysis

After adding the recent measurements, taken by Tomas Vorobjov at Kitt Peak Observatory (March 1, 2013), the distance of closest approach increased to 0.00047 AU (70 500 km). CA time is October 19, 2014, 19:09:24.48 UT. I think what we can fairly accurately estimate these parameters, before the temporary pause in the observations of this comet, due to it’s low elongation. Thanks to Tomas!

If anyone have recent measurements of this comet, I will appreciate if you will send it to me. TIA!