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Author Cochran, W.W.; Mouritsen, H.; Wikelski, M. url  doi
openurl 
  Title Migrating songbirds recalibrate their magnetic compass daily from twilight cues Type Journal Article
  Year 2004 Publication Science (New York, N.Y.) Abbreviated Journal Science  
  Volume 304 Issue 5669 Pages 405-408  
  Keywords *Animal Migration; Animals; Biological Clocks; Calibration; Cues; *Flight, Animal; Geography; *Magnetics; *Orientation; *Solar System; Songbirds/*physiology  
  Abstract Night migratory songbirds can use stars, sun, geomagnetic field, and polarized light for orientation when tested in captivity. We studied the interaction of magnetic, stellar, and twilight orientation cues in free-flying songbirds. We exposed Catharus thrushes to eastward-turned magnetic fields during the twilight period before takeoff and then followed them for up to 1100 kilometers. Instead of heading north, experimental birds flew westward. On subsequent nights, the same individuals migrated northward again. We suggest that birds orient with a magnetic compass calibrated daily from twilight cues. This could explain how birds cross the magnetic equator and deal with declination.  
  Address Illinois Natural History Survey, 607 East Peabody Drive, Champaign, IL61820, USA. Sparrow@springnet1.com  
  Corporate Author (up) Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0036-8075 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:15087541 Approved no  
  Call Number IDA @ john @ Serial 57  
Permanent link to this record
 

 
Author Rabaza, O.; Galadi-Enriquez, D.; Estrella, A.E.; Dols, F.A. url  doi
openurl 
  Title All-sky brightness monitoring of light pollution with astronomical methods Type Journal Article
  Year 2010 Publication Journal of Environmental Management Abbreviated Journal J Environ Manage  
  Volume 91 Issue 6 Pages 1278-1287  
  Keywords *Astronomy; Calibration; *Environmental Pollutants; *Light  
  Abstract This paper describes a mobile prototype and a protocol to measure light pollution based on astronomical methods. The prototype takes three all-sky images using BVR filters of the Johnson-Cousins astronomical photometric system. The stars are then identified in the images of the Hipparcos and General Catalogue of Photometric Data II astronomical catalogues, and are used as calibration sources. This method permits the measurement of night-sky brightness and facilitates an estimate of which fraction is due to the light up-scattered in the atmosphere by a wide variety of man-made sources. This is achieved by our software, which compares the sky background flux to that of many stars of known brightness. The reduced weight and dimensions of the prototype allow the user to make measurements from virtually any location. This prototype is capable of measuring the sky distribution of light pollution, and also provides an accurate estimate of the background flux at each photometric band.  
  Address Department of Civil Engineering, University of Granada, Severo Ochoa Str. s/n, 18071 Granada, Spain. ovidio@ugr.es  
  Corporate Author (up) Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0301-4797 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:20199844 Approved no  
  Call Number IDA @ john @ Serial 192  
Permanent link to this record
 

 
Author den Outer, P.; Lolkema, D.; Haaima, M.; van der Hoff, R.; Spoelstra, H.; Schmidt, W. url  doi
openurl 
  Title Intercomparisons of nine sky brightness detectors Type Journal Article
  Year 2011 Publication Sensors (Basel, Switzerland) Abbreviated Journal Sensors (Basel)  
  Volume 11 Issue 10 Pages 9603-9612  
  Keywords Calibration; Darkness; *Extraterrestrial Environment; Humans; Light; Luminescent Measurements; Netherlands; *Optical Phenomena; Optics and Photonics/*instrumentation/*methods; Sky Quality Meter; artificial lighting; intercalibration; intercomparison; light pollution; night sky brightness  
  Abstract Nine Sky Quality Meters (SQMs) have been intercompared during a night time measurement campaign held in the Netherlands in April 2011. Since then the nine SQMs have been distributed across The Netherlands and form the Dutch network for monitoring night sky brightness. The goal of the intercomparison was to infer mutual calibration factors and obtain insight into the variability of the SQMs under different meteorological situations. An ensemble average is built from the individual measurements and used as a reference to infer the mutual calibration factors. Data required additional synchronization prior to the calibration determination, because the effect of moving clouds combined with small misalignments emerges as time jitter in the measurements. Initial scatter of the individual instruments lies between +/-14%. Individual night time sums range from -16% to +20%. Intercalibration reduces this to 0.5%, and -7% to +9%, respectively. During the campaign the smallest luminance measured was 0.657 +/- 0.003 mcd/m(2) on 12 April, and the largest value was 5.94 +/- 0.03 mcd/m(2) on 2 April. During both occurrences interfering circumstances like snow cover or moonlight were absent.  
  Address National Institute for Public Health and the Environment, A. van Leeuwenhoeklaan 9, 3720 BA Bilthoven, The Netherlands. peter.den.outer@rivm.nl  
  Corporate Author (up) Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1424-8220 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:22163715; PMCID:PMC3231263 Approved no  
  Call Number IDA @ john @ Serial 196  
Permanent link to this record
 

 
Author Letu, H.; Hara, M.; Tana, G.; Nishio, F. url  doi
openurl 
  Title A Saturated Light Correction Method for DMSP/OLS Nighttime Satellite Imagery Type Journal Article
  Year 2012 Publication IEEE Transactions on Geoscience and Remote Sensing Abbreviated Journal IEEE Trans. Geosci. Remote Sensing  
  Volume 50 Issue 2 Pages 389-396  
  Keywords DMSP-OLS; remote sensing; light at night; radiometry; calibration  
  Abstract Several studies have clarified that electric power consumption can be estimated from the Defense Meteorological Satellite Program/Operational Linescan System (DMSP/OLS) stable light imagery. As digital numbers (DNs) of stable light images are often saturated in the center of city areas, we developed a saturated light correction method for the DMSP/OLS stable light image using the nighttime radiance calibration image of the DMSP/OLS. The comparison between the nonsaturated part of the stable light image for 1999 and the radiance calibration image for 1996-1997 in major areas of Japan showed a strong linear correlation (R2 = 92.73) between the DNs of both images. Saturated DNs of the stable light image could therefore be corrected based on the correlation equation between the two images. To evaluate the new saturated light correction method, a regression analysis is performed between statistic data of electric power consumption from lighting and the cumulative DNs of the stable light image before and after correcting for the saturation effects by the new method, in comparison to the conventional method, which is, the cubic regression equation method. The results show a stronger improvement in the determination coefficient with the new saturated light correction method (R2 = 0.91, P = 1.7 ·10-6 <; 0.05) than with the conventional method (R2 = 0.81, P = 2.6 ·10-6 <; 0.05) from the initial correlation with the uncorrected data (R2 = 0.70, P = 4.5 · 10-6 <; 0.05). The new method proves therefore to be very efficient for saturated light correction.  
  Address  
  Corporate Author (up) Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0196-2892 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number IDA @ john @ Serial 204  
Permanent link to this record
 

 
Author Muheim, R.; Phillips, J.B.; Akesson, S. url  doi
openurl 
  Title Polarized light cues underlie compass calibration in migratory songbirds Type Journal Article
  Year 2006 Publication Science (New York, N.Y.) Abbreviated Journal Science  
  Volume 313 Issue 5788 Pages 837-839  
  Keywords Alaska; *Animal Migration; Animals; Calibration; Cues; *Flight, Animal; Geography; *Light; Magnetics; *Orientation; Seasons; Sparrows/*physiology; Sunlight  
  Abstract Migratory songbirds use the geomagnetic field, stars, the Sun, and polarized light patterns to determine their migratory direction. To prevent navigational errors, it is necessary to calibrate all of these compass systems to a common reference. We show that migratory Savannah sparrows use polarized light cues from the region of sky near the horizon to recalibrate the magnetic compass at both sunrise and sunset. We suggest that skylight polarization patterns are used to derive an absolute (i.e., geographic) directional system that provides the primary calibration reference for all of the compasses of migratory songbirds.  
  Address Department of Animal Ecology, Lund University, Ecology Building, SE-223 62 Lund, Sweden. rmuheim@vt.edu  
  Corporate Author (up) Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0036-8075 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:16902138 Approved no  
  Call Number IDA @ john @ Serial 243  
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