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 Notes - Session 127 (2006-05-24)

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Bullet Sky Conditions
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Bullet Optimal Subexposure Durations (2)
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Goto Images from 2006-05-24

Sky Conditions

Sky Conditions Summary (S127)
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Optimal Subexposure Durations (1)

Steve Cannistra (Starry Wonders Astrophotography) has built a developed a method (including a downloadable Excel Spreadsheet tool) for Subexposure Duration Optimisation in which he optimizes subexposure durations to maximize the signal to noise ratio of faint deep sky targets in the final cumulative exposure.   

Using the method, for my camera (2.3 Gain, 15e read-out noise, 2.6 arc sec/pixel), I get the following optimal subexposure times for 0.90 and 0.95 fractions of maximum SNR

Sub-Exposure Time Sub-Exposure Time 
(bin correction)
Binning Sky Sky  F = 0.90 F = 0.95 F = 0.90 F = 0.95
ADU/min ADU/sec/sq.arc sec (secs) (secs) (secs) (secs)
2x2 50 0.16 500 1100 140 300
2x2 100 0.31 250 550 70 150
2x2 150 0.47 170 360 45 100
2x2 200 0.63 125 270 30 70
2x2 500 1.57 50 110 15 30
2x2 1000 3.14 25 60 7 15

 

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Optimal Subexposure Durations (2)

John Smith has developed a subexposure calculator based upon the need to reduce the camera's read noise component by overwhelming it with sky noise.

Using the method, for my camera (2.3 Gain, 15e read-out noise, 2.6 arc sec/pixel), I get the following optimal subexposure times for 0.90 and 0.95 fractions of maximum SNR

Sub-Exposure Time Sub-Exposure Time 
(bin correction)
Binning Sky Sky  F = 0.90 F = 0.95 F = 0.90 F = 0.95
ADU/min ADU/sec/sq.arc sec (secs) (secs) (secs) (secs)
2x2 50 0.16 500 1100 140 300
2x2 100 0.31 250 550 70 150
2x2 150 0.47 170 360 45 100
2x2 200 0.63 125 270 30 70
2x2 500 1.57 50 110 15 30
2x2 1000 3.14 25 60 7 15

 

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