EclairsOrbit

class EclairsOrbit(orbit_filename, attitude_filename)

Bases: object

Orbital computations for ECLAIRs instrument

Constructor

Parameters:

• orbit_filename (str) – name of the orbit .fits file
• attitude_filename (str) – name of the attitude .fits file

Methods Summary

create_open_fov_map(n)	Create the open field of view map, ie.
get_earth_position(n)	Return Earth angular position (theta_E, phi_E) in field of view.
get_field(field)	Get field column from already loaded data.
get_limb_angle(n)	Compute alpha limb angle at different times so as to determine whether a given pixel falls on the Earth surface or not.
is_earth_in_fov(n)	Check whether Earth appears in the instrument FOV.
is_in_saa()	Check whether the satellite is in the South Atlantic Anomaly (SAA).

Methods Documentation

create_open_fov_map(n)

Create the open field of view map, ie. a detector size array (199x199) filled with 0 and 1. Each pixel value is 0 if Earth is present and 1 otherwise.

Parameters:n (int) – row index in astropy table Returns:open fov 199x199 map Return type:2D array(bool)

get_earth_position(n)

Return Earth angular position (theta_E, phi_E) in field of view.

Read positions in fits file are in the J2000 ref frame. Need to take conjugate as matrices in algorithm are transposed.

See section 9.1 (p.50/65) in SV-SY-NT-242-JPO document (v4). See mail/code from Sujay 17 Sept 2019

Parameters:n (int) – row index in astropy table Returns:theta and phi of the Earth center in ECLAIRs frame in deg Return type:array(float) of shape (2,)

get_field(field)

Get field column from already loaded data.

Parameters:field (str) – name of the required field

get_limb_angle(n)

Compute alpha limb angle at different times so as to determine whether a given pixel falls on the Earth surface or not.

Limb angle is defined to be the angle between the earth direction and a tangent line (see AlG slides for scheme and maths)

Parameters:n (int) – row index in astropy table Returns:limb angle in degrees Return type:float Returns:Earth center to satellite distance in m Return type:float

is_earth_in_fov(n)

Check whether Earth appears in the instrument FOV.

See AlG slides for scheme and maths.

Parameters:n (int) – row index in astropy table Returns:if Earth is in FOV Return type:bool

is_in_saa()

Check whether the satellite is in the South Atlantic Anomaly (SAA).

Likely to be provided by a .fits file. No need to be recomputed.