Re: (meteorobs) LEONIDS-1996: ZHRs in So. Calif

To: meteorobs@latradedot com
Subject: Re: (meteorobs) LEONIDS-1996: ZHRs in So. Calif
From: nmcleod@peganetdot com
Date: Sun, 24 Nov 1996 23:54:42 -0500
Reply-To: meteorobs@latradedot com
Sender: owner-meteorobs
The Lunsford and Assmus data appear repeated after my comment.  Within their
tables on the far right I added my observed rate for the hour closest to
theirs, when we had an hour in common.  For Lunsford we differ by only 4
minutes.  Their observed rates (and ZHR's) with the Leonid radiant well
above the horizon compare very favorably with mine.  This shower was so
bright it should be substantially independent of sky conditions down to
perhaps LM5.5.  What we are seeing in the ZHR's below is the need to revise
the formula!  The Leonid max rate I am convinced stayed rather level for a
number of hours covering Europe and North America, but was shifting from
brighter to fainter meteors toward the end of this period.  The ZHR formula
seriously overcorrects for lower radiant elevations; here is an excellent
example of same.

Then look at Lunsford's final hour.  His sky condition deteriorated, and the
sky correction method goosed his corrected value way out of step.  Here,
too, is a perfect example of where I disagree with the correction for poorer
skies.

If my results were run through the formula, I would probably shrink to ZHR
15-20.  Let's get real here!!  That's not the way it was!  I would have seen
almost every one of the same meteors in a sky a full magnitude poorer,
perhaps even more than a magnitude.  True, this was an exceptionally
brilliant shower, but the same problem is present for all other showers to a
lesser extent.

I did have a Leonid  train percentage of 83.6% using only sky LM7.3 meteors,
an unbelievable figure.  This item is strongly dependent on sky LM, plus I
had almost no faint meteors.

Norman
Fort Myers, Florida




>           ZENITH HOURLY RATE CALCULATION FOR LUNSFORD/ASSMUS DATA
>                THE LEONID PEAK NIGHT (November 16/17, 1996)
>
>                         LUNSFORD DATA
>
>  INTERVAL       Teff   Lm      nLEO  nSPO    ZHR(Leo)  SEM(+/-)
>
>06:30-07:30 UT   1.0   6.42       1     9
>07:30-08:30 UT   1.0   6.41       8     4      99.49
35.17......................23
>08:30-09:30 UT   1.0   6.40      19     4      74.81
17.16.....................28
>09:30-10:30 UT   1.0   5.99      17     6      54.76
13.28......................39
>10:30-11:30 UT   1.0   6.13      16     7      30.64      7.66
>11:30-12:30 UT   1.0   6.33      30     8      37.44      6.84
>12:30-11:30 UT   1.0   5.77      35     9      67.78     11.46
>
>
>
>                          ASSMUS DATA
>
>08:00-09:00 UT   .94   6.10      15     3      119.00
30.726...................28
>09:00-10:00 UT   .95   6.10      12     7       44.70
12.902.....................39
>                             -break-
>11:45-12:45 UT   .93   6.00      18     2       31.35     7.389
>12:45-13:00 UT   .70   6.00      13     5       27.33     7.587
>
>
>
>     From these ZHR estimates, it sure seems like we here in S Cal caught the
> back side of the activity slope.  Any commentary?
>
>
> Joseph
>