[meteorite-list] October 4th fireball northeast of Flagstaff

[Matson, Rob D.]

Hi All,

Sorry for the premature end -- fat-fingered the send key apparently. Continuing:

Steve was also good enough to travel out to the Bellemont NWS
site that took an image of the smoke trails several minutes after
the fireball. He wrote:

"Yesterday at Bellemont Weather Station right under and in line with the camera that
took shots of the smoke clouds, I determined that they were at between 35 and 36
degrees magnetic readings.  These reading are as close as I can determine as to the
position of the clouds that day; 5 to 6 min later. ..."

"Bellemont Weather Station:
Average 35.5 degrees NE add 10.5 degrees for Celestial Pole, making it 45.5 degrees
NE from Celestial North."

Using Google Earth and aligning the view with Fremont Peak, I measured an azimuth of
55.6 degrees to the lower smoke trail (which is the more important one). The higher
cloud has an azimuth less than 1 degree to the left (i.e. lower azimuth) than the lower
cloud.  This is a large discrepancy between the two of us -- some 10 degrees. I'm
confident that the accuracy on my measurement is better than 1 degree. Looking at
Google Earth, I suspect he was aligning off the wrong peak. 45-degree azimuth points
to Mt. Humphreys, not Fremont Peak.

Another good smoke trail image was taken from downtown Flagstaff, about a half-mile
southeast of Steve. It is a little more difficult to measure the angles in this image, but
1-degree accuracy is certainly achievable.  I measured an angle of 47-degrees to the
lower cloud, very consistent with the 46.5-degree terminal azimuth I got for Steve's
camera. That the angle is slightly higher can easily be explained by a few minutes
of eastward drift by the cloud.

The 10-mile separation between the Bellemont and downtown Flagstaff cameras
is enough to get a decent range estimate to the cloud. This range is further
confirmed by a third dust trail image taken from much further to the east.

Cheers,
Rob