European Space Agency

Royal Belgian Institute for Aeronomy

um538 - evaluate the magnetic local time

subroutine  um538(mpos, amjd, xmlt, xlat, ifail)

Parameters:

• mgeo [zgeo,in] :: geocentric location

• amjd [real8,in] :: modified Julian day

• xmlt [real8,out] :: magnetic local time [MLT]

• xlat [real8,out] :: magnetic latitude

• ifail [integer4,out] :: error flag (see Diagnostics) and Dependencies

Description

The subroutine um538() evaluates the magnetic local time at a given geographic location and time. The time (argument amjd) passed to the subroutine is used to re-evaluate the position of the Sun and the GSM or SM coordinate transformation used in magnetic field evaluations (only the external magnetic field model is affected by this re-evaluation). Note that the magnetic field models have to be firstly initialized, e.g. by a call to the subroutine um510() and um520().

History

• um538() is not included in version 2.02 and earlier.

Diagnostics

• -53802, the geographic position is located too close to the geomagnetic dipole axis.

Common Blocks

• uc140 - magnetic field

• uc160 - general constants

Dependencies

Called by

None

Calls

• um522 - position of the Sun

• um523 - GEO to GSM transformation

• um524 - GEO to SM transformation

See also

• um510 - select an internal field model

• um520 - select an external magnetic field model

Reported Bugs

None

Examples

None

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UNILIB/tags/v3.03