[meteorite-list] Revisiting flightpath of Indian Butte (Stanfield/Casa Grande) bolide of 7 June 1998

From: Matson, Rob D. <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Wed, 20 Jan 2016 19:06:07 +0000
Message-ID: <4A4FA25E4DFE584AA580F4F069F9B440B52390C5_at_EMP-EXMR104.corp.leidos.com>

Hi All,

I've been revisiting the June 7th, 1998, fall over Stanfield, AZ (Indian Butte), attempting to better
constrain the original bolide flight direction. I know David Kring at the time collected hundreds of
reports from witnesses, trying to piece together the trajectory and a likely fall zone. David
correctly surmised that the fall ended somewhere between Casa Grande and Gila Bend, but
nowhere have I read a report that estimated the flight direction and entry angle. The only
mention I've seen was in a reposted article that appeared on the meteorobs list:

http://www.meteorobs.org/maillist/msg08069.html

The paragraph in particular is a witness report by Joe Montani from central Tucson:

"Joe Montani, an observer with the UA Spacewatch program, which scans the heavens
looking for comets and asteroids, saw this object from his back yard in central Tucson.
 
"He said it appeared in the sky almost due north, and while it appeared to go almost
straight down toward the ground, that likely was an optical illusion. Montani believes
it may have been moving almost parallel to the Earth's surface.
 
 "If its angle of attack had been any more shallow, it would have bounced
 off the Earth's atmosphere and back into space," Montani said.

Joe's conclusions are completely at odds with one another, so either he was misquoted or
he was completely mistaken about either the bearing or direction of motion. As we now
know, he could not possibly have seen the meteor in his north heading vertically downward.
That would have put the terminus to his north, which it certainly wasn't. He ~might~ have
first seen it in his north moving right-to-left nearly *parallel* to the ground, but that is
90 degrees different from going "almost straight down toward the ground". As an
observer with Spacewatch, Joe would know this, so I'm leaning toward a misquote by
the reporter.

The evidence in the radar data says the bolide travelled northeast to southwest with
a shallow entry angle. Was curious if this is consistent with all the reports that Kring
collected. --Rob
Received on Wed 20 Jan 2016 02:06:07 PM PST