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Determination of the Limiting MagnitudeThe limiting magnitude of an optical camera system is an important property to understand since it is used to find the completeness limit of observations. Limiting magnitude depends on the hardware and software of the system, current weather conditions, and the angular speed of the objects observed. If an object exhibits a substantial angular rate during the exposure, its light spreads out over more pixels than the stationary stars. This spreading causes the limiting magnitude to be brighter when compared to the stellar limiting magnitude. The effect, which begins to become important when the object moves a full width at half max during a single exposure or video frame. For targets with high angular speeds or camera systems with narrow field of view or long exposures, this correction can be significant, up to several magnitudes. The stars in an image are often used to measure the limiting magnitude since they are stationary, have known brightness, and are present in large numbers, making the determination of the limiting magnitude fairly simple. In order to transform stellar limiting magnitude to object limiting magnitude, a correction must be applied accounting for the angular velocity. This technique is adopted in meteor and other fast-moving object observations, as the lack of a statistically significant sample of targets makes it virtually impossible to determine the limiting magnitude before the weather conditions change. While the weather is the dominant factor in observing satellites, the limiting magnitude for meteors also changes throughout the night due to the motion of a meteor shower or sporadic source radiant across the sky. This paper presents methods for determining the limiting stellar magnitude and the conversion to the target limiting magnitude.
Document ID
20170004477
Acquisition Source
Marshall Space Flight Center
Document Type
Abstract
Authors
Kingery, Aaron
(Engineering Research and Consulting, Inc. Huntsville, AL, United States)
Blaauw, Rhiannon
(All Points Logistics, LLC Huntsville, AL, United States)
Date Acquired
May 8, 2017
Publication Date
April 18, 2017
Subject Category
Instrumentation And Photography
Optics
Report/Patent Number
M17-5636
Report Number: M17-5636
Meeting Information
Meeting: European Conference on Space Debris
Location: Darmstadt
Country: Germany
Start Date: April 18, 2017
End Date: April 21, 2017
Sponsors: European Space Agency
Funding Number(s)
CONTRACT_GRANT: NNM12AA41C
Distribution Limits
Public
Copyright
Public Use Permitted.
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