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Author Birriel, J.; Adkins, J. K. url  openurl
  Title A Simple, Portable Apparatus to Measure Night Sky Brightness at Various Zenith Angles Type Journal Article
  Year 2010 Publication (down) The Journal of the American Association of Variable Star Observers Abbreviated Journal  
  Volume 38 Issue Pages 221  
  Keywords Remote Sensing  
  Abstract We describe a simple apparatus for making measurements of night sky brightness as a function of zenith and azimuth using “off-the-shelf” equipment: a Unihedron Sky Quality Meter with Lens, a protractor with plumb-line, a tripod, and a hand-held compass. Compared to a photoelectric or CCD photometric system, this apparatus is simple to set up and use and does not require complex data reduction procedures. Thus, this apparatus makes measurements of night sky brightness as a function of zenith and azimuthal angles quite amenable to students.  
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  Call Number LoNNe @ kagoburian @; IDA @ john @ Serial 905  
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Author Birriel, J. J.; Adkins, J. K. url  openurl
  Title Sky Brightness at Zenith During the January 2019 Total Lunar Eclipse Type Journal Article
  Year 2019 Publication (down) The Journal of the American Association of Variable Star Observers Abbreviated Journal  
  Volume 47 Issue 1 Pages 94  
  Keywords Skyglow  
  Abstract Lunar eclipses occur during the full moon phase when the moon is obscured by Earth's shadow. During these events, the night sky brightness changes as the full moon rises and then passes first into the penumbral and then the umbral shadow. We acquired sky brightness data at zenith using a Unihedron Sky Quality Meter during the 20-21 January 2019 total lunar eclipse as seen from Morehead, Kentucky. The resulting sky brightness curve shows an obvious signature when the moon enters the umbral (partial) eclipse phases and the total eclipse phase. During the total eclipse phase, the brightness curve is flat and measures 19.1 ± 0.1 mag / arcsec2. The observed brightness at totality is close to typical new moon in January night at our location, which measures 19.3 ± 0.1 mag / arcsec2. The partial eclipse phase is symmetric on either side of totality. The penumbral phase is more difficult to identify in the plot, without comparison to a typical full moon night. There is a clear asymmetry in the curve just before and just after the umbral phase. This asymmetry is probably due to changes in terrestrial atmospheric conditions, such as high altitude clouds.  
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  Notes Approved no  
  Call Number IDA @ intern @ Serial 2647  
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Author Ruger, M.; St Hilaire, M.A.; Brainard, G.C.; Khalsa, S.-B.S.; Kronauer, R.E.; Czeisler, C.A.; Lockley, S.W. url  doi
openurl 
  Title Human phase response curve to a single 6.5 h pulse of short-wavelength light Type Journal Article
  Year 2013 Publication (down) The Journal of Physiology Abbreviated Journal J Physiol  
  Volume 591 Issue Pt 1 Pages 353-363  
  Keywords Adolescent; Adult; Body Temperature; Circadian Rhythm/*physiology; Female; Humans; *Light; Male; Melatonin/physiology; Young Adult; blue light; melatonin; photic response; whort-wavelength  
  Abstract The photic resetting response of the human circadian pacemaker depends on the timing of exposure, and the direction and magnitude of the resulting shift is described by a phase response curve (PRC). Previous PRCs in humans have utilized high-intensity polychromatic white light. Given that the circadian photoreception system is maximally sensitive to short-wavelength visible light, the aim of the current study was to construct a PRC to blue (480 nm) light and compare it to a 10,000 lux white light PRC constructed previously using a similar protocol. Eighteen young healthy participants (18-30 years) were studied for 9-10 days in a time-free environment. The protocol included three baseline days followed by a constant routine (CR) to assess initial circadian phase. Following this CR, participants were exposed to a 6.5 h 480 nm light exposure (11.8 muW cm(-2), 11.2 lux) following mydriasis via a modified Ganzfeld dome. A second CR was conducted following the light exposure to re-assess circadian phase. Phase shifts were calculated from the difference in dim light melatonin onset (DLMO) between CRs. Exposure to 6.5 h of 480 nm light resets the circadian pacemaker according to a conventional type 1 PRC with fitted maximum delays and advances of -2.6 h and 1.3 h, respectively. The 480 nm PRC induced approximately 75% of the response of the 10,000 lux white light PRC. These results may contribute to a re-evaluation of dosing guidelines for clinical light therapy and the use of light as a fatigue countermeasure.  
  Address Circadian Physiology Program, Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA. mrueger@rics.bwh.harvard.edu  
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  Language English Summary Language Original Title  
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  ISSN 0022-3751 ISBN Medium  
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  Notes PMID:23090946; PMCID:PMC3630790 Approved no  
  Call Number IDA @ john @ Serial 239  
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Author Revell, V.L.; Molina, T.A.; Eastman, C.I. url  doi
openurl 
  Title Human phase response curve to intermittent blue light using a commercially available device Type Journal Article
  Year 2012 Publication (down) The Journal of Physiology Abbreviated Journal J Physiol  
  Volume 590 Issue Pt 19 Pages 4859-4868  
  Keywords Adolescent; Adult; Circadian Clocks/physiology/*radiation effects; Female; Humans; *Light; Male; Melatonin/analysis/physiology; Saliva/chemistry; Young Adult; blue light  
  Abstract Light shifts the timing of the circadian clock according to a phase response curve (PRC). To date, all human light PRCs have been to long durations of bright white light. However, melanopsin, the primary photopigment for the circadian system, is most sensitive to short wavelength blue light. Therefore, to optimise light treatment it is important to generate a blue light PRC.We used a small, commercially available blue LED light box, screen size 11.2 x 6.6 cm at approximately 50 cm, approximately 200 muW cm(-2), approximately 185 lux. Subjects participated in two 5 day laboratory sessions 1 week apart. Each session consisted of circadian phase assessments to obtain melatonin profiles before and after 3 days of free-running through an ultradian light-dark cycle (2.5 h wake in dim light, 1.5 h sleep in the dark), forced desynchrony protocol. During one session subjects received intermittent blue light (three 30 min pulses over 2 h) once a day for the 3 days of free-running, and in the other session (control) they remained in dim room light, counterbalanced. The time of blue light was varied among subjects to cover the entire 24 h day. For each individual, the phase shift to blue light was corrected for the free-run determined during the control session. The blue light PRC had a broad advance region starting in the morning and extending through the afternoon. The delay region started a few hours before bedtime and extended through the night. This is the first PRC to be constructed to blue light and to a stimulus that could be used in the real world.  
  Address University of Surrey, Guildford, Surrey GU2 7XH, UK  
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  ISSN 0022-3751 ISBN Medium  
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  Notes PMID:22753544; PMCID:PMC3487041 Approved no  
  Call Number IDA @ john @ Serial 345  
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Author Wehr, T.A.; Aeschbach, D.; Duncan, W.C. url  doi
openurl 
  Title Evidence for a biological dawn and dusk in the human circadian timing system Type Journal Article
  Year 2001 Publication (down) The Journal of Physiology Abbreviated Journal J Physiology  
  Volume 535 Issue 3 Pages 937-951  
  Keywords Human Health  
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  ISSN 0022-3751 ISBN Medium  
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  Notes Approved no  
  Call Number LoNNe @ kagoburian @ Serial 831  
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