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(meteorobs) Feb 4 Hawaii Fireball, further analysis.
Based on my observations and those of Nicolas Biver on Oahu, I did a
rough estimate of the characteristics of this meteor. I used the famous
Grand Teton fireball of 1972, as a comparison, since extensive analysis
had been done on it. The latest analysis by Ceplecha, concluded that
meteor initially had a diameter from 3m to 14m, depending on
composition, chondrite vs. "dirty snowball". Using the average magnitude
estimate of -17 @ 100km height, for the Grand Teton meteor, we can
compare this Hawaii meteor, and make an estimate of its size.
Since the Teton meteor appeared at about 45° altitude in the photos, we
can use an observer distance approx. 141km for the -17 mag brightness.
Basically, using the inverse square law for brightness, I adjusted
Nicolas' observed mag -11 to -12.2 @ 141km and my observed mag -15 to
-12.4 @ 141km, for an average -12.3 @ 141km. This means the Hawaii
fireball was about 1/75 the luminosity of the Teton fireball. Assuming
the luminosity is approximately proportional to the surface area, that
means the diameter of our fireball was about 11.5% that of the Teton
one. Therefore its diameter would be around 35 cm, if chondritic or 1.6m
if dirty snowball. Assuming about 50% of its mass was lost during the
burn phase, an object between 28 cm and 128 cm plunged into the Pacific
Ocean off Maui last night.
Mike.
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