# Meteors from comet 209P/LINEAR

Meteor outburst predicted for 2014 May 24th, peak activity close to 07:00 UT. Significant proportion of bright meteors; possibility of fireballs.

# Predicting the outburst using dust trail theory

In this context "dust trail theory" refers to the fact that the set of meteoroids released from a parent comet during a single perihelion return stretch out into a dense, narrow dust trail during their early orbital evolution. The theory calculates (by numerical integration) the evolution of a single, representative particle at each point along the trail, rather than calculating the evolution of particles with any possible 3-dimensional ejection velocity. A meteor outburst is predicted if a trail comes close enough to the earth. This technique works if the timescale is short enough. The idea goes back many years (e.g. Plavec 1956) and was successfully applied by the Kazan research group (Kondrat'eva & Reznikov 1985, Kondrat'eva et al. 1997 etc.) to many streams.

For comet 209P, dust trail encounters were first calculated by Esko Lyytinen when Peter Jenniskens realised the possibility of close approaches (Jenniskens 2006). Further extensive dust trail calculations were made by Mikhail Maslov (2014 outburst; description; computation and comet orbit; 1901-2100 predictions). The data in the table below were calculated by David Asher with the same program used for the Leonids by McNaught & Asher (1999).

UT - Universal Time unadjusted for topocentric correction
Revs - number of orbits of dust from ejection to 2014
Ep - ejection epoch (year)
Da0 - difference between semi-major axis (a0) of the comet and the particle at ejection. Da0~0.0 => large particles
rE-rD - distance of the dust trail node from Earth's orbit (Earth radius=0.00004AU) (Impact radius=0.00005AU) (trail widths can easily be a few Earth diameters, depending on ejection velocities)
fM - estimate of the along-trail dispersion. For a 1-rev trail, fM= 1.0 but for an unperturbed n-rev trail, fM= 1/n. Negative values indicate that the trail flows back on itself.

Year Mo DaUT Revs Ep Da0 rE-rD fM
2014 05 2408:0020 19140.002 0.00202-0.229
2014 05 2407:2421 19090.001 0.00061-0.149
2014 05 2407:0922 19030.001 0.00005-0.113
2014 05 2407:0123 18980.001-0.00025-0.095
2014 05 2406:5524 18930.001-0.00044-0.082
2014 05 2406:5225 18880.000-0.00057-0.074
2014 05 2406:4826 18830.000-0.00067-0.067
2014 05 2406:4527 18780.000-0.00079-0.050
2014 05 2406:4228 18730.000-0.00086-0.040
2014 05 2406:3929 18680.000-0.00090-0.033
Year Mo DaUT Revs Ep Da0 rE-rD fM
2014 05 2406:3830 18630.000-0.00093-0.029
2014 05 2406:3731 18580.000-0.00095-0.026
2014 05 2406:3732 18530.000-0.00096-0.020
2014 05 2406:3533 18480.000-0.00097-0.021
2014 05 2406:3434 18430.000-0.00097-0.022
2014 05 2406:3435 18380.000-0.00099 -.---
2014 05 2406:3436 18330.000-0.00100 -.---
2014 05 2406:3437 18280.000-0.00101 -.---
2014 05 2406:3438 18230.000-0.00102 -.---
2014 05 2406:3439 18180.000-0.00102 -.---
Year Mo DaUT Revs Ep Da0 rE-rD fM
2014 05 2406:3440 18130.000-0.00101 -.---
2014 05 2406:3441 18080.000-0.00101 -.---
2014 05 2406:3842 18030.000-0.00099-0.017
2014 05 2406:3743 17980.000-0.00096-0.023
2014 05 2406:3944 17930.000-0.00091-0.031
2014 05 2406:4745 17880.000-0.00078-0.054
2014 05 2407:1446 17830.001-0.00043-0.116
2014 05 2407:4747 17780.001 0.00001-0.047
2014 05 2408:0248 17730.001 0.00019 -.---
2014 05 2408:0949 17680.001 0.00030 -.---
2014 05 2408:1450 17630.001 0.00038 -.---
2014 05 2408:1951 17580.001 0.00046 -.---
2014 05 2408:2252 17530.001 0.00054 -.---
• The full table shows that dust trails <20-rev old have large rE-rD i.e. too distant for meteors, but lie mostly in the Ye & Wiegert (their Fig.2) highest density zone
• The 22 and 47-rev trails have approx. direct hits
• Trails between 27 and 45-revs are almost coincident with each other, but offset from the Earth's orbit
• Dust trails >52-rev old are still in the Earth's vicinity, but strongly disrupted and not well suited for dust trail prediction
• The trails align across the Earth's orbit almost perpendicularly, so peak at similar times (Leonid trails were more scattered)
• The first trails to be encountered are older, then younger and finally much older
• Dust trail calculations are based on the centre of the Earth. A time adjustment is needed for when a specific location passes through the dust sheet
• The 46-rev trail would combine with the main 22-rev peak
• The 47-rev trail will be a direct hit but this and older trails are encountered much later. This should give a second lower peak with a slow tail off
In conclusion:
• Main peak centred around the 22-rev trail at 07:09UT (unadjusted), superimposed on a broader shower with slow rise and sharper fall off
• A lower peak from the 47-rev trail at 07:47UT (unadjusted) should have a sharp rise and slower decline

Could the outburst fail to occur?

• Was comet 209P/LINEAR active at these epochs a hundred to two hundred years ago, releasing the meteoroids for us to see on 2014 May 24 as meteors? All we know from observations of the comet is that it was active at its recent returns (2004, 2009 and present). However, there is at least no obvious reason why it should not have been active at those past epochs.
• The accuracy of the data is the table is very dependent on the accuracy of the comet orbit at those past epochs, which is not constrained by observations. But if the comet has behaved similarly in the past compared to the decade in which it has been observed, then the data are fairly reliable.

## Visibility map:

Region of Earth that can see meteors from comet 209P on 2014 May 24 at 07:00 UT
• Map shows that North (excluding far north) and Central America, and the north of South America, get night or twilight at the right time. As the meteors are expected to be bright on average, twilight observing should be reasonable; conceivable you could see one or two fireballs in daylight. However, hard to know whether peak meteor rate will be low or high, because of lack of past observed meteor outbursts due to this comet.
• Dotted red circles show observed radiant elevation at 10 degree intervals, from 10 to 80 deg, with black, solid, outer circle denoting radiant on horizon. Observed means corrected for zenithal attraction: the observed (apparent) radiant will be higher in the sky due to the gravitational bending of the incoming meteors by the Earth (to a max. of 11 deg for meteors on these orbits).
• Small green cross (near radiant elevation 80 deg circle) is the north pole, i.e. for times slightly different from 07:00 GMT, the continents are slightly rotated around this point (twilight lines remaining fixed). Significant meteor activity may occur an hour or two before and after maximum.
• Centre of map faces the point in the constellation Camelopardalis (the giraffe) where the meteors radiate from.

### Topocentric correction to trail encounter times:

• Predictions are for the Earth's centre
• But different parts of the Earth's surface are at slightly different points in space, and so encounter the dust trails at slightly different times
• Peak will be 8 mins earlier from N America

Computer models:
Jeremie Vaubaillon, IMCCE
Ye and Wiegert (2014)
Mikhail Maslov

Meteor shower/outburst:
Peter Jenniskens (includes extensive summary of main work done during the decade since the comet's discovery)
Quan-Zhi Ye (May 21) (May 13)
International Meteor Organization
IMO, Camelopardalids visual data quicklook
Society for Popular Astronomy
NASA Science News
IAU MDC meteor shower 451 CAM Camelopardalids

Comet:
209P/LINEAR (Seiichi Yoshida)
209P/LINEAR (Gary Kronk)
209P image (NASA/MSFC/Bill Cooke)
Images and analysis of 209P tail (Quan-Zhi Ye)
Rob McNaught's discovery of cometary activity in 2004: this object was originally known as near-earth asteroid 2004 CB
JPL Small-Body Database Browser
Minor Planet Center (includes observations)

Webpage by David Asher using input (plot data and plenty more) from Rob McNaught
Maps drawn using PGPLOT; coastline data from NOAA National Geophysical Data Center

 Last Revised: 2014 May 28th