irfpy.jdc.frame1

Frame definition. Based on JUI-ADST-INST-TN-000122_01

The frame of the JDC is defined, though it is not the final. JDC’s frame0

Spacecraft frame

  • +z: nadir deck

  • -z: zenith deck.

  • -x: HGA

JDC will be located at the edge of +x/-z.

JDC1 frame

  • +z: JDC symmetric axis. The JDC looking hemisphere is +x hemisphere.

  • +x: Open direction (same direction as SC frame)

  • -x: Toward the thruster (and HGA direction)

Note also that JDC would have a tilt around y axis, due to the contamination from the thrusters. The angle of tilt is not yet determined. Thus, this angle would be given as a parameter.

Conversion between JDC & SC

The conversion matrix is as follows:

\[x_SC \cos\theta 0 \sin\theta x_JDC y_SC = 0 -1 0 y_JDC z_SC \sin\theta 0 -\cos\theta z_JDC\]

Convert between the JDC0 angles and vectors

The converion of the angles to JDC1 frame is implemented. See angles2jdc() and jdc2angles(). The definition follows the definition of myself. Thus, the coordinate system may be chagned in the future.

The definition is consistent to the one defined in fov1. The elevation angle, \(\theta\), 0 is the zenith (z axis) and 180 for the nadir looking direction. The azimutha angle, \(\phi\), 0 is x axis and 90 for y axis.

Angle \(\theta\) and \(\phi\) is the polar coordinate system of the JDC1 frame.

Convert from NSC vectors to physical frame

The conversion is implemented in irfpy.pep.pep_attitude module.

irfpy.jdc.frame1.angles2jdc(theta, phi)[source]

Return the unit vector corresponding to the given angles.

Parameters

  • theta (float) – Theta in degrees. Float or (N,) shape np.array.

  • phi (float) – Phi in degrees. Float or (N,) shape np.array.

Returns

The corresponding vector with shape of (3,) or (3, N)

Return type

np.array

>>> print(angles2jdc(0, 0))
[ 0.  0.  1.]

The following returns the corresponding vector for \((\theta, \phi) = (0, 0), (1, 1), (2, 2), ...\) at once.

>>> print(angles2jdc(np.arange(181), np.arange(181)).shape)
(3, 181)
irfpy.jdc.frame1.jdc2angles(vec)[source]

Return the JDC angle for the corresponding JDC vector.

Parameters

vec (np.array) – np.array, with (3,) or (3, N) shape.

Returns

Theta and Phi

Return type

np.array with (2,) or (2, N) shape.

>>> print(jdc2angles([1, 0, 0]))
[90.  0.]

For multiple vectors, you can convert to angles. Note that the shape should be (3, N), thus, the array should look like np.array([[x0, x1, x2, ...], [y0, y1, y2, ...], [z0, z1, z2, ...]])

>>> print(jdc2angles([[1, 10, 0, 1], [0, 0, 1, 0], [0, 0, 0, 1]]))
[[90. 90. 90. 45.]
 [ 0.  0. 90.  0.]]
irfpy.jdc.frame1.nsc2jdc(vecnsc, tilt=0)[source]

Convert from NSC to JDC.

Parameters

  • vec – (3,) or (3,N) array.

  • tilt – Tilt angle in degrees.

vec should be (3,) or (3,N) array.

>>> nsc = [ 1., -2.,  3.]
>>> print(nsc2jdc(nsc))
[ 1.  2. -3.]
>>> nsc = [-1.41421356, -2.,          2.82842712]
>>> print(nsc2jdc(nsc, tilt=45))
[ 1.          2.         -2.99999999]
>>> nscs = [[ 2.,  1.,  0., -1.,  2.,],
... [-1., -1., -1., -1., -1.],
... [-3., -1.,  0.,  1.,  3.]]
>>> print(nsc2jdc(nscs))
[[ 2.  1.  0. -1.  2.]
 [ 1.  1.  1.  1.  1.]
 [ 3.  1.  0. -1. -3.]]
irfpy.jdc.frame1.jdc2nsc(vecjdc, tilt=0)[source]

Convert from JDC to (N)SC.

Parameters

  • vec – (3,) or (3,N) array.

  • tilt – Tilt angle in degrees.

\[x_SC \cos heta 0 \sin heta x_JDC y_SC = 0 -1 0 y_JDC z_SC \sin heta 0 -\cos heta z_JDC\]
>>> jdc = [1, 2, -3]
>>> print(jdc2nsc(jdc))
[ 1. -2.  3.]
>>> print(jdc2nsc(jdc, tilt=45))
[-1.41421356 -2.          2.82842712]
>>> jdcs = [ [ 2,  1,  0, -1,  2],
...          [ 1,  1,  1,  1,  1],
...          [ 3,  1,  0, -1, -3]]
>>> print(jdc2nsc(jdcs))
[[ 2.  1.  0. -1.  2.]
 [-1. -1. -1. -1. -1.]
 [-3. -1.  0.  1.  3.]]
irfpy.jdc.frame1.doctests()[source]