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Published byCarol Jeffrey Modified over 9 years ago
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Using a DSLR to Study Variable Stars
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Canon 450D - linear over a magnitude using RAW images with a specific setting
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Canon 85 mm fixed lens- can be used to do precise estimates down to magnitude 8 ( undriven ).
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Canon 200 mm fixed lens- can be used to do precise estimates down to magnitude 10 ( undriven ).
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Precision Photometry Eye: +/- 0.1 m Standard DSLR Photometry: +/- 0.03m Precise DSLR Photometry: +/- 0.01m
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Precision Photometry The right settings for the right signal to noise ratio (SNR -100)
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Precision Photometry Epsilon Aurigae & 85 mm lens: Exposure 5 secs,ISO 200, f5 Exposure 5 secs, ISO 200, f4.5 Exposure 5 secs:ISO 200. f4.
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Precision Photometry Centered target stars The effect of wind Remote Switch Careful Focus Long Exposure Dark Frames
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Standard DSLR Photometry +/- 0.03m ten images analysed
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200 mm lens - exposure 3.2 secs, f2.8, ISO 800 images every ten/fifteen minutes
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85 mm lens, exp 5 secs, f3.5, ISO 800
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200 mm lens - exposure 2.5 secs, f2.8, ISO 800
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Variations of 0.2/0.3 magnitude - a new world of variables
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Precision DSLR Photometry +/- 0.01m thirty/ fifty images analysed
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Estimates of the 20/2/10 JD: 2455248.367 Camera Settings with an 85 mm lens: Exposure-5 seconds, ISO 200, f4. 5 sets of ten images: Analysed with AIP4WIN v2.1.10 (1) 3.776V (2) 3.777V (3) 3.774V (4) 3.769V (5) 3.781V Average = 3.775V Standard Deviation = 0.004
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AIP4WIN - analysis of RAW images
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Dark frames Flat Fields
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Multi-image deep sky stacking procedure - 30 minutes to analyse 50 images
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V Photometry Green Channel Images Transformation Co-efficient
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Estimates of the 10/3/10 JD: 2455266.327 Camera Settings with an 85 mm lens: Exposure-5 seconds, ISO 200, f4. 5 sets of ten images: Analysed with AIP4WIN v2.1.10 (1) 3.769V (2) 3.760V (3) 3.776V (4) 3.764V (5) 3.758V Average = 3.765V Standard Deviation = 0.007
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Deciphering Epsilon Aurigae
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Presentation of estimates
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DSLR Cameras - not as sensitive as CCD cameras because they are not cooled - but yield just as good results down to mag 10.5 desloughney@blueyonder.co.uk
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