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Constants used by this crate
Constants§
- AE
- Distance units / Earth radii.
- ASTRONOMICAL_
UNIT_ KM - Astronomical unit in kilometers (IAU 76)
- C1L
- Lunar perturbation coefficient
(C_m in units radians/minute, p. 29) - C1SS
- Solar perturbation coefficient
(C_s in units radians/minute, p. 29) - CK2
- Corresponds to
1/2 * J_2 * a_E^2.J_2is the second gravitational zonal harmonic of Earth,a_Eis the equatorial radius of Earth. - CK4
- Corresponds to
-3/8 * J_4 * a_E^4, whereJ_4is the fourth gravitational zonal harmonic of Earth. - DEG_
TO_ RAD - Degrees to Radians conversion factor
- E6A
- Shorthand for 10^-6.
- EARTH_
ANGULAR_ VELOCITY - Angular velocity of Earth in radians per seconds
- EARTH_
RADIUS_ KM_ WGS84 - WGS 84 Earth radius km, XKMPER in spacetrack report #3
- EARTH_
ROTATIONS_ PER_ SIDERIAL_ DAY - Earth rotations per siderial day
- FLATTENING_
FACTOR - Flattening factor
- FLT_
EPSILON - G22
- Constants for secular update for resonance effects of Earth gravity
(G_22, G_32, G_44, G_52 and G_54, p. 36) - G32
- See above
- G44
- See above
- G52
- See above
- G54
- See above
- GEOSYNCHRONOUS_
ECCENTRICITY_ THRESHOLD - upper eccentricity for geosynchronous satellites
- GEOSYNCHRONOUS_
INCLINATION_ THRESHOLD_ DEGREES - upper inclination for geosynchronous satellites
- GEOSYNCHRONOUS_
LOWER_ MEAN_ MOTION - lower mean motion for geosynchronous satellites
- GEOSYNCHRONOUS_
UPPER_ MEAN_ MOTION - upper mean motion for geosynchronous satellites
- J3_
HARMONIC_ WGS72 - J3 Harmonic (WGS ’72), XJ3 in spacetrack report #3
- JULIAN_
TIME_ DIFF - Difference between libpredict’s
predict_julian_date_tand the julian time format used in some of the internal functions - MAXELE_
MAX_ NUM_ ITERATIONS - Maximum number of iterations in
find_max_elevation - MAXELE_
TIME_ EQUALITY_ THRESHOLD - Threshold used for comparing lower and upper brackets in
find_max_elevation - MINUTES_
PER_ DAY - Number of minutes per day, XMNPDA in spacetrack report #3
- NAUTICAL_
TWILIGHT_ SUN_ ELEVATION - Upper elevation threshold for nautical twilight
- Q22
- Constants for one-day resonance conditions, satellite-independent for 1-day period satellites
(Initialization of resonance effects of Earth gravity, Q_22, Q_31 and Q_33, p. 31) - Q31
- See above
- Q33
- See above
- QOMS2T
- Corresponds to
(q_0 - s)^4in units (earth radii)^4, whereq_0and s are parameters for the SGP4/SGP8 density function. - RAD_
TO_ DEG - Radians to Degrees conversion factor
- ROOT22
- Constants for 1/2-day resonance conditions, satellite-independent for 1/2-day period satellites (Initialization for resonance effects of Earth gravity,
sqrt(C_ij^2 + S_ij^2)where ij = 22, 32, 44, 52 and 54, p. 32) - ROOT32
- See above
- ROOT44
- See above
- ROOT52
- See above
- ROOT54
- See above
- SECONDS_
PER_ DAY - Number of seconds per day
- SOLAR_
RADIUS_ KM - Solar radius in kilometers (IAU 76)
- SPEED_
OF_ LIGHT - Speed of light in vacuum
- S_
DENSITY_ PARAM - Parameter for SGP4/SGP8 density function.
- THDT
- The time-derivative of the Greenwich hour angle in radians per minute (\dot{\theta}, used on p. 36. Not directly defined in report, but values and naming are consistent with this)
- THREE_
PI_ HALF - Half of three times PI
- TWO_
THIRD - two thirds
- XKE
k_e = sqrt(Newton's universal gravitational * mass of the Earth), in units (earth radii per minutes)^3/2- ZCOSGS
- Corresponds to
cos(omega_s)(omega_s defined on p. 29, no description. See comment above) - ZCOSIS
- Cosine of the solar inclination
(not defined directly in the paper, but corresponds with cos(I_s) with I_s as the solar inclination on p. 29) - ZEL
- Lunar eccentricity
(e_m, p. 29) - ZES
- Solar eccentricity
(e_s, p. 29) - ZNL
- Lunar mean motion
(n_m in units radians/minute, p. 29) - ZNS
- Solar mean motion
(n_s in units radians/minute, p. 29) - ZSINGS
- Corresponds to
sin(omega_s)(omega_s defined on p. 29, no description. See comment above) - ZSINIS
- Sine of the solar inclination
(sin(I_s),I_s on p. 29. See comment above)