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Returns a value in arcsec for gravitational light bending using equation 25 of Cowling 1984, MNRAS 209, 415; or equation 40 if asteroidAngle is specified. See also deflectionPlot.


au.deflection(angleDegrees=90, m=1.989e+33, r=14959700000000.0, asteroidAngle=None, vis=None, field=None)
  • angleDegrees: angle between star and bending object
  • m: mass of central object (default = Msun)
  • r: distance from bending object (default = 1 AU)
  • asteroidAngle: the observer-sun-asteroid angle in degrees, a.k.a. Observer-Primary-Target angle on JPL Horizons (if not specified, then assume the star is at infinite distance)
  • vis: measurement set from which to read a field position and date/time for getting location of the Sun (using angleToSun)
  • field: field ID or name


CASA <2>: tt.deflection()
  Out[2]: 0.0040719103797911974
CASA <6>: tt.deflection(angleDegrees=0.25)
  Out[6]: 1.8664232733626516
CASA <11>: tt.deflection(angleDegrees=81.684, asteroidAngle=70.17)  # Juno Band 6 observations
  Out[11]: 0.0028601942592516583
CASA <10>: tt.deflection(angleDegrees=86.694)  # Juno Band 6 phase calibrator
  Out[10]: 0.004313910923460223

The following example demonstrates that at 542 AU from the Sun, the plane wavefront from a distant object behind the Sun is focused from an annulus at the solar limb (of radius 1.76 arc seconds) into a single point, forming a natural telescope of astonishing collecting area.
CASA <40>: tt.deflection(angleDegrees=1.7581/3600., r=542*1.5e13)
  Out[40]: 1.7580940515928094

-- ToddHunter - 2015-03-24
Topic revision: r5 - 2015-08-27, ToddHunter
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