2 Preamble Imaging the Universe - University of Liverpoolsdb/Talks/Imaging-Univ-CAS.pdf · Aurora...
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Imaging the Universe Dr Steve Barrett 1 26 Apr 2006 Splash Dr Steve Barrett 26/4/06 Imaging the Universe 2 Preamble Computing Photography Wildlife Astronomy 3 Preamble Computing Photography Wildlife Astronomy 4 Preamble Milky Way 6 Overview Principles Detecting Colours Keeping the Image Sharp Amateurs Professionals Detecting Light Practice
Transcript of 2 Preamble Imaging the Universe - University of Liverpoolsdb/Talks/Imaging-Univ-CAS.pdf · Aurora...
Imaging the Universe
Dr Steve Barrett 1 26 Apr 2006
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Imaging
the Universe
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Computing
Photography
Wildlife
Astronomy
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Computing
Photography
Wildlife
Astronomy
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5 Milky Way 6 OOOOvvvveeeerrrrvvvviiiieeeewwww
Principles
Detecting ColoursKeeping the Image Sharp
AmateursProfessionals
Detecting Light
Practice
Imaging the Universe
Dr Steve Barrett 2 26 Apr 2006
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RetinaCornea
Lens
Light → chemistry → perception
8 Rods+ConesRods
Cones
→ lightintensity
→ colourif plentyof light
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Light → chemistry→ change in transparency
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Light → electrons→ amplify → memory
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Colour Filters
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Colour Film
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CCD Chip
Imaging the Universe
Dr Steve Barrett 3 26 Apr 2006
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Red Green Blue
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Image Format
JPEG is a processed image"Raw" = image from CCD
For astrophotography, rawformat is very desirable
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All images have noise
Dark image subtraction
Need actual (raw) image
Increases with exposure
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Image
Dark
Image – Dark
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Key Problems
Long ExposuresThe Earth Moves!
Low Light Levels
Solutions
"Track" the StarsKeep Exposures Short
Imaging the Universe
Dr Steve Barrett 4 26 Apr 2006
19 PPPPhhhhoooottttoooossss oooonnnn aaaa FFFFiiiixxxxeeeedddd TTTTrrrriiiippppoooodddd
Use Tripod (or a Rock)Keep Exposures Short
Use Cable/Remote Release
Take Advantage ofHoliday Skies
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The different colours areproduced by the oxygenand nitrogen atoms, andthe shapes are formed bythe Earth’s magnetic field
Particles from the Sun hitthe Earth’s atmosphere,making the air glow
Aurora are best seen nearthe Arctic or Antarcticcircles
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Aurora Borealis Exp=30s f/2.8 F L=24mm Fujichrome ISO400
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North Polar Sky Exp=5m f/2.8 F L=24mm Fujichrome ISO200
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North Polar Sky Exp=1hr f/5.6 F L=24mm Fujichrome ISO400
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Southern Sky Exp=5m f/2.8 F L=24mm Fujichrome ISO200
Imaging the Universe
Dr Steve Barrett 5 26 Apr 2006
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Pyramids Exp=5s f/2.8 F L=24mm
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Milky Way Exp=2m f/2.8 F L=18mm D70
27 Rufiji Scorpius 28 Rufiji Crux
Southern Cross Exp=2m f/2.8 F L=18mm D70
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One 120s
exposure
Six 20s
exposures
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Imaging the Universe
Dr Steve Barrett 6 26 Apr 2006
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33 TTTToooottttaaaallll EEEEcccclllliiiippppsssseeee ooooffff tttthhhheeee SSSSuuuunnnn 34
1/4000 s
1/1000 s
1/250 s
1/60 s
1/15 s
1/4 s
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35 TTTToooottttaaaallll EEEEcccclllliiiippppsssseeee ooooffff tttthhhheeee SSSSuuuunnnn 36 FFFFoooolllllllloooowwwwiiiinnnngggg tttthhhheeee SSSSttttaaaarrrrssss
The Earth rotates
Rotate one rev per day Axis ~ parallel with Earth's
"De"-rotate the camera
Solutions
"Piggy-back" on a telescope Build a motorised mount
Imaging the Universe
Dr Steve Barrett 7 26 Apr 2006
37 PPPPiiiiggggggggyyyy----BBBBaaaacccckkkk PPPPhhhhoooottttooooggggrrrraaaapppphhhhyyyy
M45 Pleiades Star Cluster Exp=300s f/4 F L=300mm D70
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C20 North America Nebula Exp=600s f/4 F L=200mm D70
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M31 Andromeda Galaxy Exp=600s f/4 F L=300mm D70
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There aremanytypes oftelescopesavailable,making achoicesomewhatconfusing
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RefractorsUse lenses to focusthe light
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ReflectorsUse mirrors to focusthe light
RefractorsUse lenses to focusthe light
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Imaging the Universe
Dr Steve Barrett 8 26 Apr 2006
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Schmidt-CassegrainsUse both lenses andmirrors
RefractorsUse lenses to focusthe light
ReflectorsUse mirrors to focusthe light
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Compact S-CHave user–friendlycontrollers to pointthe telescope
RefractorsUse lenses to focusthe light
ReflectorsUse mirrors to focusthe light
Schmidt-CassegrainsUse both lenses andmirrors
''''GGGGoooottttoooo'''' TTTTeeeelllleeeessssccccooooppppeeeessss
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A domedobservatoryprovides astableplatform forthe telescopeand shelterfrom the wind
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The Hale telescopewas built in the1940s and has amirror 5m (200”)in diameter.
For half a century,it remained theworld’s largesttelescope.
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A converted shed isa cheaper solution
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Imaging the Universe
Dr Steve Barrett 9 26 Apr 2006
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M51 Exp=15m f/6.3
F L=1350mm CCD
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A nebula is acloud of gasthat reflectslight fromnearby stars
This is a star‘nursery’where starsare being born
51 OOOOrrrriiiioooonnnn NNNNeeeebbbbuuuullllaaaa 52 SSSSaaaattttuuuurrrrnnnn
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Imaging the Universe
Dr Steve Barrett 10 26 Apr 2006
55 M51 56 CCCCaaaatttt''''ssss EEEEyyyyeeee
57 MMMM111100004444 58 RRRRaaaawwww++++PPPPrrrroooocccc
59 HHHHuuuubbbbbbbblllleeee DDDDeeeeeeeepppp FFFFiiiieeeellllddddHHHHuuuubbbbbbbblllleeee
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Amateurs
Cover the Whole SkyTime is 'Free'
Professionals
Limited Sky CoverageTelescope Time Expensive
Imaging the Universe
Dr Steve Barrett 11 26 Apr 2006
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£ 1,000,000,000
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£ 1,000,000
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£ 1,000
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£ 100
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£ 10
