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Spacewatch was founded in 1980 by Tom Gehrels and Robert S. McMillan, and is currently led by astronomer Melissa Brucker at the University of Arizona. Spacewatch uses several telescopes on Kitt Peak for follow-up observations of near-Earth objects. [3] The Spacewatch Project uses three telescopes of apertures 0.9-m, 1.8-m, and 2.3-m.
A chart datum is the water level surface serving as origin of depths displayed on a nautical chart and for reporting and predicting tide heights. A chart datum is generally derived from some tidal phase, in which case it is also known as a tidal datum. [1] Common chart datums are lowest astronomical tide (LAT) [1] and mean lower low water (MLLW).
Associated with this mask will be water level elevations with an accuracy of 10 cm (3.9 in) for water bodies whose non-vegetated surface area exceeds 1 km 2 (0.39 sq mi). The slope accuracy is 1.7 cm/km (1.1 in/mi) over a maximum 10 km (6.2 mi) of flow distance. [7]
The USGS HydroSHEDS dataset was generated for hydrological applications and is suitable for consistent drainage and water flow information. References are provided [13] on the algorithms used and quality assessment. [14] The void-filled SRTM data from Viewfinder Panoramas by Jonathan de Ferranti [15] are high quality at full SRTM resolution ...
The Dymaxion map projection, also called the Fuller projection, is a kind of polyhedral map projection of the Earth's surface onto the unfolded net of an icosahedron. The resulting map is heavily interrupted in order to reduce shape and size distortion compared to other world maps , but the interruptions are chosen to lie in the ocean.
McFeeters index: If looking for water bodies or change in water level (e.g. flooding), then it is advisable to use the green and NIR spectral bands [18] or green and SWIR spectral bands. Modification of normalised difference water index (MNDWI) has been suggested for improved detection of open water by replacing NIR spectral band with SWIR. [19]
GNSS systems that provide enhanced accuracy and integrity monitoring usable for civil navigation are classified as follows: [5] GNSS-1 is the first generation system and is the combination of existing satellite navigation systems (GPS and GLONASS), with Satellite Based Augmentation Systems (SBAS) or Ground Based Augmentation Systems (GBAS). [5]
Water level, also known as gauge height or stage, is the elevation of the free surface of a sea, stream, lake or reservoir relative to a specified vertical datum. [1]