Changes between Initial Version and Version 1 of TargetLocation

Timestamp:

06/09/05 12:19:42 (20 years ago)

Author:

rick

Comment:

--

TargetLocation

@@ +1 @@
+Note -- need to clean up HTML encoded entities.  -- Joe
+
+== Target Location ==
+
+Target location, by which is meant the spatial location of the target
+region of imaged or pointed observations on or around the Sun or in
+the heliosphere, has not yet been built into any VSO query models,
+although it is a fairly natural selection criterion for observations
+with a restricted field of view.  It may suffice to specify a simple
+uniform description, although the multi-dimensionality of space makes
+this harder than one for time.  For two-dimensional image data we assume
+a bounding circle as the simplest model.  For this model it is sufficient
+to specify the center location and radius of the bounding circle.
+Most real image data are actually described by a bounding rectangle,
+but this requires specifying at least five parameters (''e.g.''
+the coordinates of opposite corners and a position angle).  
+
+
+==== Observation_Center_West ====
+
+
+  type: ''number''[[BR]]
+  unit: ''arc-second''[[BR]]
+  FITS keyword: ''CENT_WST''
+
+==== Observation_Center_North ====
+
+
+  type: ''number''[[BR]]
+  unit: ''arc-second''[[BR]]
+  FITS keyword: ''CENT_NRT''
+
+  A pair of coordinates specifying the location of the center of the
+image data circle with respect to the Earth-Sun line at the nominal
+Observation_Time.  This origin is close to the center of
+the apparent solar image for Earth-based or near-Earth observers, but
+not necessarily for deep space observations.  The North coordinate
+is measured in the direction of the Carrington axis (RA 286 °13,
+δ 63°.87 J2000.0), and the West coordinate in the direction
+of solar rotation.
+
+
+==== Bounding_Radius ====
+
+
+  type: ''number''[[BR]]
+  unit: ''arc-second''[[BR]]
+  FITS keyword: ''R_BOUND''[[BR]]
+
+  The radius of the bounding circle about the Observation_Center.
+For the VSO Data Model the bounding circle is to be understood as either
+the maximum inscribed circle in the bounding data rectangle (polygon),
+or the minimum circumscribed circle, depending on whether the query is
+for included data (presumably the normal default) or excluded data,
+respectively.