Embed Size (px)
Citation preview
Sk B i ht M t ithSky Brightness Measurements with a Digital Camera:Digital Camera:
The Effect of a Small Nearby Village (Großmugl) on Night Sky Brightness
Georg ZottiGeorg Zotti
Wiener Arbeitsgemeinschaft für Astronomie
& Österreichischer Astronomischer Verein
Outline
Sky Luminance and Stellar VisibilityHi h D i R Ph t hHigh Dynamic Range PhotographyEvaluation of HDR imagesEvaluation of HDR imagesUrban vs Rural Night SkyUrban vs. Rural Night SkyGroßmugl Experiment,Großmugl Experiment, Astronomy Day 2008
Georg Zotti 1
Sky Luminance and Stellar Visibility
Human VisionHuman Vision
Full Moon SunsetFull Moon Sunset
Instrument VisionGeorg Zotti 2
Instrument Vision[after Weaver 1947, Garstang 1986, Cinzano 1997]
High Dynamic Range Photography
Combination of several exposuresCalibration with Luminance Meter
Luminance MapPh t hiPhotographic Measurement System
Georg Zotti 3
Our SystemCamera: Digital SLR
All Sky Fisheye only with Full Size Chip DSLRsAll-Sky Fisheye only with Full-Size Chip DSLRs RAW image format!
F S ftFree Software: Dcraw for RAW image processinghttp://cybercom.net/~dcoffin/dcraw/PFS Tools for HDR processing p ghttp://www.mpi-inf.mpg.de/resources/pfstools/
Extensible via GNU OctaveExtensible via GNU OctaveCalibration:
PFS Tools from EXIF data (approximative)PFS Tools, from EXIF data (approximative)Minolta LS-110 for daylight range
Georg Zotti 4
Sky Quality Meter for night sky measurements
Evaluation of Zenith Luminance
Series of HDR photos Averaged zenith area
TonemappedHDR images
Georg Zotti 5
HDR images
Evaluation of Zenith Luminance
Sun alt
cd/m²alt.
Georg Zotti 6
Evaluation of Zenith Luminance
Georg Zotti 7
Results: Surburb SkyFull illumination Reduced illumination
Georg Zotti 8
Results: Surburb SkyFull illumination Reduced illumination
Georg Zotti 9
Results: City Border (average)Full illumination Reduced illumination
Georg Zotti 10
Results: City Border (good night)Full illumination Reduced illumination
Georg Zotti 11
Results: City Border / 20km from Viennamag5.5 Großmugl near Vienna, mag6
Vienna
Georg Zotti 12
Results: 20km from Vienna / UnpollutedGroßmugl near Vienna, mag6.2 Pristine Sky (Mongolia) mag6.3
Vienna
Georg Zotti 13
Results: 20km from Vienna / UnpollutedGroßmugl near Vienna, mag6.2 Pristine Sky (Mongolia) mag6.3
Georg Zotti 14
A Rare View: Dark Clouds at Night!
Georg Zotti 15
Astronomy Day, 2008-05-10, Großmugl
2 illuminatedroads
Georg Zotti 16
Astronomy Day, 2008-05-10, Großmugl
2 illuminatedBLACKroads
1 illuminatedroadroad
Georg Zotti 17
Astronomy Day, 2008-05-10, Großmugl
2 illuminatedBLACKroads
1 illuminatedroad
BLACKroad
Lights off
Georg Zotti 18
Astronomy Day, 2008-05-10, Großmugl
Lights offGroßmugl
ViGeorg Zotti 19
Vienna
Astronomy Day, 2008-05-10, Großmugl
Lights offBLACKGroßmugl
1 illuminatedroadroad, 10 minutesafter power-on
ViGeorg Zotti 20
Vienna
Astronomy Day, 2008-05-10, Großmugl
Lights offBLACKGroßmugl
1 illuminatedroad
BLACKroad, 10 minutesafter power-on
Back to „normal“
ViGeorg Zotti 21
Vienna
Astronomy Day, 2008-05-10, Großmugl
Lights offBLACKGroßmugl
1 illuminatedroad
BLACKroad, 10 minutesafter power-on
Back to „normal“
ViGeorg Zotti 22
Vienna
Astronomy Day, 2008-05-10, Großmugl
Lights offGroßmugl
ViGeorg Zotti 23
Vienna
Astronomy Day, 2008-05-10, Großmugl
Lights offBLACKGroßmugl
Back to „normal“
ViGeorg Zotti 24
Vienna
Open Questions
Calibration:Reference photometer not sensitive enoughfor dark scenefor dark sceneSQM sensitivity non-photopicSQM (older model) field of view difficult
Wh t i th b t“ k b i ht it?What is the „best“ sky brightness unit?cd/m²cd/mmag/arcsec²Limiting visual magnitude
Can we agree on a common colour scale?Can we agree on a common colour scale?Georg Zotti 25
Street Luminaires at Kuffner Observatory
Last SundayLast Sunday
MoonMoon
Street lamp
Georg Zotti 26
Street Luminaires at Kuffner Observatory
Last SundayLast Sunday
Moon TuesdayMoon
Street lamp
Georg Zotti 27
Street Luminaires at Kuffner Observatory
Last SundayLast Sunday
Moon TuesdayMoon
Street lamp
Georg Zotti 28
Street Luminaires at Kuffner Observatory
Georg Zotti 29
Conclusions
All-Sky Luminance Measurement SystemCalibrated HDR Imaging SystemSimple extensions to PFS ToolsSimple extensions to PFS ToolsFalse-Colour Plots
For “technical” astronomers: mag/arcsec²For visual star watching: limiting visual magnitudesg g gPFS base units: cd/m²
Light Pollution in rural areas ruins esp horizon skyLight Pollution in rural areas ruins esp. horizon skyEffect of road light reduction clearly visible
Thank you for Your AttentionGeorg Zotti 30
Thank you for Your AttentionGeorg Zotti <[email protected]>
