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Re: (meteorobs) Leonids from Arizona and question
Meteor photography with a 28mm f/2.8 lens.
This thread is a bit old, but I've just reached it in the thousands of
email messages awaiting me on my return a few days ago.
During the Leonid peak this year, I operated 5 Canon T70s with 28mm f/2.8
lenses and Tri-X (processed 6min D19 at 20C). One lens had a problem (as
I'd discovered before observing, and wouldn't stop down below f/5.6). All
lenses were taped to infinity and full aperture with masking tape to
prevent stupid mistakes that inevitably happen if you don't try to account
for every eventuality beforehand. All cameras were automated in the way
developed by Robert Hass.
The cameras were automated to do 37 exposures of 4m58s duration with 2 sec
between exposures and the start time was arranged to put the predicted
peak time of 02:07 UT (for Jordan) in the middle of an exposure :-)
Around the peak time, I have 30+ Leonids on individual exposures for the
camera with the radiant in the field of view. It would appear that I have
photographed several hundred individual Leonids. I shall examine each
individual exposure in detail and derive the number of individual meteors
for each 5 minute period. It will also be interesting to see the
distribution of numbers with respect to elevation and elongation from the
radiant.
The photographic rate for an individual camera was very close to 10% of my
visual rate for that general region of sky, although I would likely have
been visually covering a much wider region. This rather suggests to me
that I was photographing mag +2 Leonids around 30 degrees of the radiant.
Will investigate further.
My 15mm f/2.8 and 8mm f/2.8 fisheyes were also automated on Canon T70s, so
I was completely free to make visual observations (except for having to
change the tape in my dictaphone right on maximum :-( These fisheyes show
much lower rates than in 1998 overall, although the peak 15 to 20
minutes came close. However these were mostly weak images (brightest was
around mag -6) unlike last years rain of fireballs.
Cheers, Rob
Robert H. McNaught
rmn@aaocbn.aaodot gov.au
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