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Author Nielsen, E.T.
Title Illumination at twilight Type Journal Article
Year 1963 Publication Okios Abbreviated Journal (up)
Volume 14 Issue 1 Pages 9-21
Keywords Animals; Instrumentation; Methods
Abstract Introduction Poikilotherms with a nocturnal or crepuscular period of activity are usually guided by changes in illumination. The releasing factor may be a certain low level of illumination, or it might be a certain rate of change of intensity or a combination of both. ASCHOFF (1960) has shown that also animals with an internal clock mechanism of activation have to have the “clock” reset by actual changes in illumination. To all students of such animals it is essential to measure light intensity and its changes especially during the twilight period.
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Call Number GFZ @ kyba @ Serial 3196
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Author Burggraaff, O., Schmidt, N., Zamorano, J., Pauly, K., Pascual, S., Tapia, C., Spyrakos, E., & Snik, F.
Title Standardized spectral and radiometric calibration of consumer cameras Type Journal Article
Year 2019 Publication Optical Express Abbreviated Journal (up)
Volume 27 Issue 14 Pages 19075-19101
Keywords Instrumentation
Abstract Consumer cameras, particularly onboard smartphones and UAVs, are now commonly used as scientific instruments. However, their data processing pipelines are not optimized for quantitative radiometry and their calibration is more complex than that of scientific cameras. The lack of a standardized calibration methodology limits the interoperability between devices and, in the ever-changing market, ultimately the lifespan of projects using them. We present a standardized methodology and database (SPECTACLE) for spectral and radiometric calibrations of consumer cameras, including linearity, bias variations, read-out noise, dark current, ISO speed and gain, flat-field, and RGB spectral response. This includes golden standard ground-truth methods and do-it-yourself methods suitable for non-experts. Applying this methodology to seven popular cameras, we found high linearity in RAW but not JPEG data, inter-pixel gain variations >400% correlated with large-scale bias and read-out noise patterns, non-trivial ISO speed normalization functions, flat-field correction factors varying by up to 2.79 over the field of view, and both similarities and differences in spectral response. Moreover, these results differed wildly between camera models, highlighting the importance of standardization and a centralized database.
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Call Number IDA @ intern @ Serial 2652
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Author Lee, B., Lee, Y., Kim, D., & Kim, S.
Title Correction of Lunar Irradiation Effect and Change Detection Using Suomi-NPP Data Type Journal Article
Year 2019 Publication Korean Journal of Remote Sensing Abbreviated Journal (up)
Volume 35 Issue 2 Pages 265-278
Keywords Instrumentation
Abstract Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) data help to enable rapid emergency responses through detection of the artificial and natural disasters occurring at night. The DNB data without correction of lunar irradiance effect distributed by Korea Ocean Science Center (KOSC) has advantage for rapid change detection because of direct receiving. In this study, radiance differences according to the phase of the moon was analyzed for urban and mountain areas in Korean Peninsula using the DNB data directly receiving to KOSC. Lunar irradiance correction algorithm was proposed for the change detection. Relative correction was performed by regression analysis between the selected pixels considering the land cover classification in the reference DNB image during the new moon and the input DNB image. As a result of daily difference image analysis, the brightness value change in urban area and mountain area was

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30

radiance and below

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radiance respectively. The object based change detection was performed after the extraction of the main object of interest based on the average image of time series data in order to reduce the matching and geometric error between DNB images. The changes in brightness occurring in mountainous areas were effectively detected after the calibration of lunar irradiance effect, and it showed that the developed technology could be used for real time change detection.
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Call Number IDA @ intern @ Serial 2720
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Author Wilson, T., & Xiong, X.
Title Intercomparison of the SNPP and NOAA-20 VIIRS DNB High-Gain Stage Using Observations of Bright Stars Type Journal Article
Year 2020 Publication IEEE Transactions on Geoscience and Remote Sensing Abbreviated Journal (up)
Volume Issue Pages 1-8
Keywords Remote Sensing; Instrumentation
Abstract The Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi-NPP (SNPP) and NOAA-20 (N20) spacecrafts is a multispectral Earth-observing instrument with bands covering wavelengths from visible to long-wave infrared. Among these bands is a panchromatic day/night band (DNB) with a broad spectral response ranging from 500 to 900 nm, and a high dynamic range spanning over seven orders of magnitude, allowing for observations to take place during both daytime and nighttime. The DNB operates at three gain levels, with low- and mid-gain stages and two high-gain stages (HGSs). The HGS is capable of detecting dim city lights during Earth-view observations at night as well as bright stars through the instrument space-view port. Since SNPP and N20 are at opposite points of the same orbit, each VIIRS instrument is able to observe the same stars with the DNB in successive orbits. This will allow us to make a direct comparison of the relative calibration of each instrument using stars over a range of spectral classes. In this article, we develop methodology for accurately identifying target stars in order to make proper comparisons between the DNB HGS of each instrument. We then take observations from multiple stars in order to compute the ratio in the measured irradiance for each instrument as a function of spectral class. For K-type stars, which have the least spectral change over the DNB wavelength range, we measure a calibration bias between the SNPP and N20 DNB HGS of approximately 4%, which is stable over the duration of the N20 mission.
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Call Number IDA @ intern @ Serial 2959
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Author Ngadiman, N. F., Shariff, N. N. M., & Hamidi, Z. S.
Title Sensor Technology for Night Sky Brightness Measurements in Malaysia Type Journal Article
Year 2020 Publication International Journal of Recent Technology and Engineering (IJRTE) Abbreviated Journal (up)
Volume 8 Issue 6 Pages
Keywords Instrumentation
Abstract Artificial light at night is apparently showing to be a major contributor to the increase of sky brightness at night. The natural darkness in large regions of the world including Malaysia currently is at risk. Hence, some Night Sky Brightness (NSB) measurements in Malaysia were conducted by using several types of light sensors in order to serve quantitative data and spread awareness on this issue. This paper aims to analyze the sensor technology that have been used in night sky brightness measurement in Malaysia as well as to identify recent or significant advances and discoveries in this field of study. In this paper, the author adopted qualitative method through literature review from numerous conducted studies by other researchers in order to perceive better understanding on the use of dedicated light sensor in NSB related research. Starting from 2005 until now, it is noticeable that most of the light sensor used in the NSB studies in Malaysia was Sky Quality Meter (SQM) photometer, equipped with TSL237 sensor which has high irradiance responsivity 2.3kHz/(µW/cm2) @ λp = 524nm and 5 Milion:1 input dynamic range as well as able to sense down to 0.00002 Lux and has typical dark frequency down to 0.1 Hz. The result indicates the relative frequency of the SQM usage in NSB studies was 76% compared to PBM, APC, PMT and CDD of only 4% respectively. SQM has always been the choice of researchers in Malaysia to carry out their sky brightness measurements due to user-friendly implementation besides its reliable data obtained from TSL237 sensor which capable to convert the light directly to frequency without an amplifier or data converter. Thus, the nonlinearities and voltage offsets in the data can be circumvented. A fairly good development of sensor that have been utilized in NSB studies can be discerned patently besides NSB studies will always look forward for a better sensor to further enhance the efforts to map sky brightness for preserving the potential dark sky areas for the sake of astronomy.
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Call Number IDA @ intern @ Serial 2968
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