|   | 
Details
   web
Records
Author Cochran, W.W.; Mouritsen, H.; Wikelski, M.
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 (up) 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 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 Muheim, R.; Phillips, J.B.; Akesson, S.
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 (up) 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 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
Permanent link to this record
 

 
Author Rabaza, O.; Galadi-Enriquez, D.; Estrella, A.E.; Dols, F.A.
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 (up) 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 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 Bará, S.; Tapia, C.; Zamorano, J.
Title Absolute Radiometric Calibration of TESS-W and SQM Night Sky Brightness Sensors Type Journal Article
Year 2019 Publication Sensors Abbreviated Journal Sensors
Volume 19 Issue (up) 6 Pages 1336
Keywords Instrumentation; calibration; SQM; TESS; photometer; sky brightness
Abstract We develop a general optical model and describe the absolute radiometric calibration of the readings provided by two widely-used night sky brightness sensors based on irradiance-to-frequency conversion. The calibration involves the precise determination of the overall spectral sensitivity of the devices and also the constant G relating the output frequency of the light-to-frequency converter chip to the actual band-weighted and field-of-view averaged spectral radiance incident on the detector (brightness). From these parameters, we show how to define a rigorous astronomical absolute photometric system in which the sensor measurements can be reported in units of magnitudes per square arcsecond with precise physical meaning.
Address Departmento Física Aplicada, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain; salva.bara(at)usc.es
Corporate Author Thesis
Publisher MDPI Place of Publication Editor
Language English Summary Language English Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1424-8220 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 2263
Permanent link to this record