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novas_frame Struct Reference
Observing frames

A set of parameters that uniquely define the place and time of observation. More...

`#include <novas.h>`

## Data Fields

enum novas_accuracy | accuracy
| NOVAS_FULL_ACCURACY or NOVAS_REDUCED_ACCURACY.
double | beta
| Observer relativistic pseed, β = v/_c_ rel SSB.
double | deps0
| [rad] Modeled Earth orientation ε (not including polar wobble)
double | dpsi0
| [rad] Modeled Earth orientation ψ (not including polar wobble)
double | dx
| [mas] Polar wobble parameter dx.
double | dy
| [mas] Polar wobble parameter dy.
double | earth_pos [3]
| [AU] Earth's geometric position, rel SSB. (ICRS)
double | earth_vel [3]
| [AU/day] Earth's velocity, rel SSB. (ICRS)
double | ee
| [rad] Equation of the equinoxes
double | era
| [deg] Earth Rotation Angle (ERA);
double | gamma
| Observer Lorentz factor Γ rel SSB.
struct novas_matrix | gcrs_to_cirs
| GCRS to CIRS conversion matrix.
double | gst
| [h] Greenwich (Apparent) Sidereal Time (GST / GAST)
struct novas_matrix | icrs_to_j2000
| ICRS to J2000 matrix.
double | mobl
| [rad] Mean obliquity
struct novas_matrix | nutation
| nutation matrix (IAU 2006 model)
double | obs_pos [3]
| [AU] Observer position rel. to barycenter (ICRS)
double | obs_vel [3]
| [AU/day] Observer movement rel. to barycenter (ICRS)
struct novas_observer | observer
| The observer location, or NULL for barycentric.
struct novas_planet_bundle | planets
| Planet positions and velocities (ICRS).
struct novas_matrix | precession
| precession matrix
uint64_t | state
| An internal state for checking validity.
double | sun_pos [3]
| [AU] Sun's geometric position, rel SSB. (ICRS)
double | sun_vel [3]
| [AU/day] Sun's velocity, rel SSB. (ICRS)
struct novas_timespec | time
| The instant of time for which this observing frame is valid.
double | tobl
| [rad] True obliquity
double | v_obs
| [AU/day] Magnitude of observer motion rel. to barycenter

## Detailed Description

A set of parameters that uniquely define the place and time of observation.

The user may initialize the frame with novas_make_frame(). Once the observer frame is set up, it can be used repeatedly to perform efficient calculations of multiple objects in the coordinate system of choice, much faster than what place() can do. Frames also allow for transforming coordinates calculated for one coordinate syste, into another coordinate system with little effort.

You should never set or change fields in this structure manually. Instead the structure should always be initialized by an appropriate call to novas_make_frame(). After that you may change the observer location, if need be, with novas_change_observer().

The structure may expand with additional field in the future. Thus neither its size nor its particular layout should be assumed fixed over SuperNOVAS releases.

Since
  1.1

See also
  novas_make_frame(), novas_change_observer(), novas_make_transform(), NOVAS_FRAME_INIT
  novas_sky_pos(), novas_geom_posvel(), novas_geom_to_app(), novas_app_to_geom(), novas_app_to_hor(), novas_hor_to_app(), novas_rises_above(), novas_sets_below(), novas_transit_time()

The documentation for this struct was generated from the following file:

- /build/supernovas-Ly00hg/supernovas-1.5.1/include/novas.h