Last evening, Peter Jenniskens investigated what appears to be the first confirmed meteorite recovered from this fall. Below is a brief report and some pictures (courtesy P. Jenniskens SETI Institute/NASA ARC). SETI has proposed the name Novato meteorite, pending approval by the Meteorite Nomenclature Committee.
Lisa Webber
Credit: SETI
At the time of last Wednesday’s fireball, a rock was heard hitting the roof by homeowner Lisa Webber, Administrative Nurse I at the Department of Dermatology of the University of California, San Francisco Medical Center, an inhabitant of Novato, California. After reading Dave Perlman’s article in the San Francisco Chronicle on Saturday, describing the NASA/CAMS meteor trajectory predicted impact area centered on Novato, Lisa remembered hearing the sound and went outside to search for the rock that hit.
The CAMS project obtained two views of the fireball track, one by our regular 20-camera station, the other by the single-camera station at San Mateo College. We calculated a trajectory and projected a fall area in the North Bay, from east of Rafael over Novato towards Sonoma/Napa.
Credit: SETI
Credit: SETI
“I wasn’t sure at first”, says Jenniskens. “The meteorite looks very unusual, because much of the fusion crust had come off.” To help investigate the fall site, Rivera and Jenniskens inspected the recently newly resurfaced roof and Rivera found a small dent that was consistent with the meteorite having hit the roof from a SW direction.
Impact dent
Credit: SETI
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Luis Rivera with impact dent.
Credit: SETI
The meteorite appears to be a breccia, with light and dark parts. That makes it interesting to find out how diverse this meteorite is from future finds. Jenniskens plans to tally future finds and assign those a find number to possibly relate properties of the meteorites to their location in the strewnfield and association in the asteroid.
“The significance of this find”, says Jenniskens, “is that we can now hope to use our fireball trajectory to trace this type of meteorite back to its origins in the asteroid belt.”
The find helps define the trend line along which other meteorites would have fallen. The line runs from just east of San Rafael, over west Novato, towards Sonoma. According to Jenniskens, it is likely that larger fragments fell NNE towards Sonoma. Rains are predicted starting this evening, so he hopes that more meteorites will be recovered today.
Preliminary trajectory calculated by Peter Jenniskens from Sunnyvale and San Mateo College Observatory CAMS video data.
On 2012, October 18 – Only one of the three regular 20-camera CAMS stations caught the fireball, the NASA/CAMS Sunnyvale station (Jim Albers). For the two other sites, the fireball was just outside the field of view. Fortunately, thanks to the single-CAMS program run by Dave Sammuels), there was a single-CAMS camera setup at the San Mateo College observatory (Dean Drumheller). That one camera provides the second view for triangulation. The video is too bloomed for the regular software processing to work, but the average frames show a nice streak, which was used to combine with the early trajectory part from Sunnyvale, using AstroRecord and FIRBAL software.
The preliminary trajectory is plotted in the image above. The potential fall area is over land. The asteroid entered at a speed of 14 km/s, typical but on the slow side of other meteorite falls for which orbits were determined. Good chance a relatively large fraction of this rock survived. The fall area is in the North Bay. The orbit in space is also rather typical: perihelion distance close to Earth’s orbit (q = 0.987 AU) and a low-inclination orbit (about 5 degrees). Much more accurate results will follow from a comprehensive study of the video records. Now, we hope that someone recovers a meteorite on the ground…
Image by San Mateo College student Paola-Castillo, using her cell phone while stuck in traffic.
Image by Rachel Fritz and Rick Nolthenius of Cabrillo College, Aptos
Post Credit: Before It’s News
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