refract.c File Reference

Functions
double	novas_inv_refract (RefractionModel model, double jd_tt, const on_surface *loc, enum novas_refraction_type type, double el0)
double	novas_optical_refraction (double jd_tt, const on_surface *loc, enum novas_refraction_type type, double el)
double	novas_radio_refraction (double jd_tt, const on_surface *loc, enum novas_refraction_type type, double el)
double	novas_standard_refraction (double jd_tt, const on_surface *loc, enum novas_refraction_type type, double el)

Detailed Description

Date

Created on Jun 27, 2024

Author

Attila Kovacs

A collection of refraction models and utilities to use with novas_app_to_hor() or novas_hor_to_app().

See also

novas_app_to_hor()

novas_hor_to_app().

Function Documentation

novas_inv_refract()

double novas_inv_refract	(	RefractionModel	model,
		double	jd_tt,
		const on_surface *	loc,
		enum novas_refraction_type	type,
		double	el0
	)

Computes the reverse atmospheric refraction for a given refraction model. Thus if a refraction model takes observed elevation as an input, the reverse refraction takes astrometric elevation as its input, and vice versa.

Parameters

model	The original refraction model
jd_tt	[day] Terrestrial Time (TT) based Julian data of observation
loc	Pointer to structure defining the observer's location on earth, and local weather
type	Refraction type to use for the original model: REFRACT_OBSERVED (-1) or REFRACT_ASTROMETRIC (0).
el0	[deg] input elevation for the inverse refraction model.

Returns

[deg] Estimated refraction, or NAN if there was an error (it should also set errno to indicate the type of error).

See also

refract_astro()

itrs_to_hor()

Since

1.1

Author

Attila Kovacs

References novas_inv_max_iter, and NOVAS_REFRACT_OBSERVED.

novas_optical_refraction()

double novas_optical_refraction	(	double	jd_tt,
		const on_surface *	loc,
		enum novas_refraction_type	type,
		double	el
	)

Returns an optical refraction correction using the weather parameters defined for the observer location.

Parameters

jd_tt	[day] Terrestrial Time (TT) based Julian data of observation (unused in this implementation of RefractionModel)
loc	Pointer to structure defining the observer's location on earth, and local weather
type	Whether the input elevation is observed or astrometric: REFRACT_OBSERVED (-1) or REFRACT_ASTROMETRIC (0).
el	[deg] Astrometric (unrefracted) source elevation

Returns

[arcsec] Estimated refraction, or NAN if there was an error (it should also set errno to indicate the type of error).

See also

novas_app_to_hor()

novas_optical_refraction()

NOVAS_STANDARD_ATMOSPHERE()

refract()

refract_astro()

References NOVAS_WEATHER_AT_LOCATION.

novas_radio_refraction()

double novas_radio_refraction	(	double	jd_tt,
		const on_surface *	loc,
		enum novas_refraction_type	type,
		double	el
	)

Atmospheric refraction model for radio wavelengths (Berman & Rockwell 1976). It uses the weather parameters defined for the location, including humidity. As such make sure the weather data is fully defined, and that the humidity was explicitly set after calling make_on_surface().

Adapted from FORTAN code provided by Berman & Rockwell 1976.

REFERENCES:

1. Berman, Allan L., and Rockwell, Stephen T. (1976), NASA JPL Technical Report 32-1601

Parameters

jd_tt	[day] Terrestrial Time (TT) based Julian data of observation (unused in this implementation of RefractionModel)
loc	Pointer to structure defining the observer's location on earth, and local weather. Make sure all weather values, including humidity (added in v1.1), are fully populated.
type	Whether the input elevation is observed or astrometric: REFRACT_OBSERVED (-1) or REFRACT_ASTROMETRIC (0).
el	[deg] source elevation of the specified type.

Returns

[deg] Estimated refraction, or NAN if there was an error (it should also set errno to indicate the type of error).

See also

novas_optical_refraction()

make_on_surface()

on_surface

References on_surface::humidity, novas_inv_refract(), novas_radio_refraction(), NOVAS_REFRACT_ASTROMETRIC, NOVAS_REFRACT_OBSERVED, on_surface::pressure, and on_surface::temperature.

novas_standard_refraction()

double novas_standard_refraction	(	double	jd_tt,
		const on_surface *	loc,
		enum novas_refraction_type	type,
		double	el
	)

Returns an optical refraction correction for a standard atmosphere.

Parameters

jd_tt	[day] Terrestrial Time (TT) based Julian data of observation (unused in this implementation of RefractionModel)
loc	Pointer to structure defining the observer's location on earth, and local weather
type	Whether the input elevation is observed or astrometric: REFRACT_OBSERVED (-1) or REFRACT_ASTROMETRIC (0).
el	[deg] Astrometric (unrefracted) source elevation

Returns

[deg] Estimated refraction, or NAN if there was an error (it should also set errno to indicate the type of error).

See also

novas_app_to_hor()

novas_optical_refraction()

NOVAS_STANDARD_ATMOSPHERE()

refract()

refract_astro()

References NOVAS_STANDARD_ATMOSPHERE.