(meteorobs) Finding Meteorites From Observations

[prospector at znet.com]

I'm not seeing any adjustments in the search areas for the rotation of the
Earth. It is significant, 457 meters per second (1500 feet) at the equator
and zero at the poles. I'm not an expert but the direction of the meteor to
the north/south axes, the latitude and the last point the meteor seen have
to be considered. I believe I've read that the dark flight lasts about 120
seconds. At the equator that would put the impact zone 55 km or 34 miles
from the expected point of impact. Impact tables should be caculated for
various angles and latitudes for meteorobs by those capable, then maybe
some meteorites could then be found from observations.
                                    Dave English
                               Oceanside, California



Quoting Mike Hankey <mike.hankey at gmail.com>:

> Chris,
>
> Thanks for the reply and info. I understand about the dark flight, but
> its also my understanding that the dark flight model is tied to the
> trajectory / ground track. I also understand the ground track can only
> be as good as the field research that is done on the original videos.
> So at this point my strategy is improving the ground readings so we
> can improve the trajectory and then the dark flight model. I believe
> for this fall the radiosonde data has been collected and is being used
> in the current projections. (problem is we've searched the heck out of
> the current area and are still coming up with nada).
>
> Unfortunately we do not have video from the all sky meteor cams but
> rather security tape and amateur footage. It sure would be nice if the
> whole country or world was covered with these all sky cams (i'm
> planning on adding one at my house for next time).
>
> For the fall I'm working we have a total of 10 recordings: 2 direct
> video recordings, 3 use-able shadow recordings, 4 flash of light
> recordings and 1 photograph. Up to this point the direct sighting
> recordings were not calibrated / they were more eyeballed with low
> quality copies of the videos. And none of the work to measure the
> shadows was ever done. (that's next on my list after completing the
> stellar calibrations.) My thoughts were, if I could put in the time to
> properly do the field work it would improve the trajectory and dark
> flight model (probably a pipe dream, but I'm running out of options
> and time).
>
> Thanks,
>
> Mike
>
> On Tue, Oct 13, 2009 at 11:48 AM, Chris Peterson <clp at alumni.caltech.edu>
> wrote:
> > Mike-
> >
> > Even if you know the fireball trajectory with high precision, this
> doesn't
> > usually get you very close to a landing location. That depends
> primarily on
> > the winds experienced by material during dark flight. That effect can
> be
> > significant: a meteorite strewn field can lie in front of, to the side,
> or
> > behind the point of retardation (or terminal explosion). The deviation
> can
> > be miles. It is critical in analyzing any fireball with the intent of
> > locating meteorites to obtain data for the most recent local radiosonde
> > launch providing wind speed and direction at high altitudes. Otherwise,
> > there is no way to accurately estimate the landing area.
> >
> > Chris
> >
> > *****************************************
> > Chris L Peterson
> > Cloudbait Observatory
> > http://www.cloudbait.com
> >
> >
> >
> >> Pat,
> >>
> >> I would be very interested in seeing your spread sheet for calculating
> >> the trajectory and landing locations, even the simplified version.
> >> I've been working a fall in PA and I've recently been calibrating the
> >> original videos by re-shooting stellar objects from the same cameras
> >> (its turning out great).  I've gotten much better ALT AZ readings from
> >> them after doing the calibration. Your xls sounds very interesting to
> >> me and re-working the ground path is next on my list of things to do.
>