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Re: (meteorobs) Re: ZHR
On the subject of the AMS database:
Lew writes:
> nothing to do with our discussion re: education). That issue is that the
> huge mass of AMS observer data is not merely "contaminated" with
> non-standard observing methods (which can be worked around), but is....
Circo wrote:
I don't know the situation with the AMS data, but I want to raise the
rhetorical question, anyway: Can it really be worked around?
Lewis and Circo:
Rhetorical or not, the answer is a qualified yes. Obviously, a high degree
of data selectivity and careful methodology will need to be applied, but it
can be done.
During his long career, Dr. Olivier made significant strides in improving
and standardizing the AMS data collection techniques, as well as expanding
the standard data set for each meteor observed. The single visual observer
under dark skies was his baseline, not teams. As one moves forward in
time, the data quality improves steadily. While the correction factors
which Dr. Olivier used during analysis were simplistic by todays standards,
the raw data is still present toward which newer methods could be applied,
especially for the data covering the second half of the century.
While data collected for the Meteor Count Program has limited use (depending
upon the additional information provided by the observer), properly
completed forms for the Magnitude, Color, and Plotting programs carry the
same basic data set that NAMN and IMO forms carry today. The primary
difference between AMS and IMO in this regard is that we do not require the
observer to begin the data reduction process, such as computing correction
factors for Teff or F. The AMS observer also makes broader use of the
"Comments" section of the form, in order to record events such as breaks,
changes in limiting magnitude, and FOV changes.
The data recorded about each meteor includes time (UTC), magnitude, color,
duration (sec), angular length (deg), train duration, shower association (if
any), and any additional notes. Those members who plotttted would also
include the sky position for the meteor, on a standard gnomic projection for
a portion of the celestial sphere. Norman knows better than I how long
these forms and methods have been around, but I know that it has been for
some time. The only data points for which accuracy has possibly improved
are the inclusion of plotting time in Teff, and limiting magnitude, which
many observers rounded to the nearest 1/2 increment, although a few did
estimate theirs to the 1/5 or 1/10 mag using detailed star charts for
comparison. Latitude and Longitude would also need to be computed from the
observer's recorded geographic location, if needed.
The biggest problem facing us is not "contamination," but, as Jim B stated,
converting the data into a form which would allow it to be easily worked
with using modern statistical techniques. The data collected since the last
Olivier catalogue (about 1975) has been set aside, and will receive first
priority for modernization.
Take care,
Jim Richardson
AMS Radiometeor Project Coordinator
Graceville, FL
richardson@digitalexp.com