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Re: (meteorobs) Accounting for airmass in LM
In a message dated 8/18/2001 6:10:57 PM Eastern Daylight Time,
mlinnolt@alum.mitdot edu writes:
<< You should use a star field at an elevation that corresponds to the
weighted average airmass over your FOV. This way the LM
estimate best represents the overall condition, not an inflated value.
This optimum elevation is given by: arcsin(1/weighted mean
airmass).
For some typical FOV elevations, here is the optimum comparison
star field elevation to be used (100° wide field assumed):
FOV elev. Weighted mean airmass Star field elev.
-------------- ----------------------------------- --------------------
75° 1.18 58°
70° 1.24 54°
65° 1.32 49°
60° 1.45 44°
55° 1.67 37°
Mike Linnolt
>>
Mike:
I may be dense, or something, but please explain why one
wouldn't use a star field at exactly the elevation of one's
center of FOV?
Bob Young
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