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Re: (meteorobs) Facing the Radiant, Part Deux

Lew asked:
>This last item intrigued me, in light of our recent debate about facing the
>radiant! Peter sites a article from Meteor News #57 by Moore & Morrow
>[1982] in reference to this. Has anyone else read this paper, and could you
>summarize M&M's conclusions? Based on what folks on the list have already
>said, I'd *guess* that the skew is toward *brighter* meteors the further
>from the radiant you are, but perhaps the opposite is true! Care to
>comment, Peter?

Lew, without going into all the details of their study, they summarized that:

"the average magnitude does indeed brighten with an increase in the
observers' distance from the radiant. We found, however, that there was a
strange variation in the graphs of number of meteors vs. distance from
radiant. The a Caps show the 'typical' results we had for six of the seven
showers; a bell-type curve , with the greater number of meteors being seen
approximately 30o from the radiant."

This study was conducted from observations of the N & S Delta Aquarids, N &
S Iota Aquarids, Alpha Capricornids, Capricornids and Piscis Austrinids. An
example of what their graphs show is for example, the SDAs:

magnitude     Obs. Dist. from Radiant
   4.0                  ~18o
   3.6                  ~25o
   3.2                  ~35o
   2.8                  ~45o
   2.4                  ~55o
   2.0                  ~68o

and for the SIAs:

magnitude     Obs. Dist. from Radiant
   4.0                  ~21o
   3.6                  ~30o
   3.2                  ~38o
   2.8                  ~45o
   2.4                  ~55o
   2.0                  ~68o

For the CAPs:

Total Seen        Distance from radiant
   ~9                      ~23o
   ~32                     ~25o
   ~53                     ~30o
   ~57                     ~35o
   ~31                     ~40o
   ~10                     ~43o
   ~5                      ~50o
   ~8                      ~60o

and for the SDAs:

Total Seen        Distance from radiant
   ~15                     ~16o
   ~22                     ~37o
   ~36                     ~45o
   ~43                     ~49o
   ~54                     ~41o

Note that I "read" these distances off the graphs by eye from their best-fit
line, the "approximates (~)" in the above tables are mine. Also, they noted
the "unusual" behavior of the SDAs in the last table, stating "The S. Delta
Aqr. differed in that the number of meteors observed continued to increase
with the distance from the radiant. We question whether or not this is an
accurate picture of this shower, but have included the results and offer
them as a puzzle to be solved by some curious observers."

Hope this helps!

Mark Davis
NAMN Coordinator
MeteorObs@charlestondot net