HST Keyword Dictionary

Space Telescope Science Institute

3700 San Martin Drive

Baltimore, MD 21212

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Keyword Definitions for the

dated 14-APR-94

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ARGPERIG
argument of perigee 
Datatype: REAL*8              
Units:    REV
Orbital element for model of HST orbit. A parameter of the flight software model of the HST orbit.

Source : POCC

CIRVELOC
circular orbit linear velocity 
Datatype: REAL*8              
Units:    METERS/SEC
Orbital element for model of HST orbit. A parameter of the flight software model of the HST orbit.

Source : POCC

COSINCLI
cosine of inclination 
Datatype: REAL*8              
Units:    NONE
Orbital element for model of HST orbit. A parameter of the flight software model of the HST orbit.

Source : POCC

ECBDX3
eccentricity cubed times 3 
Datatype: REAL*8              
Units:    NONE
Used in model of HST orbit. See ECCENTRY to get eccentricity by itself. A parameter of the flight software model of the HST orbit.

Source : POCC

ECBDX4D3
eccentricity cubed times 4/3 
Datatype: REAL*8              
Units:    NONE
Used in model of HST orbit. See ECCENTRY to get eccentricity by itself. This is a parameter of the flight software model of the HST orbit.

Source : POCC

ECCENTRY
eccentricity 
Datatype: REAL*8              
Units:    NONE
Orbital element for model of HST orbit. A parameter of the flight software model of the HST orbit.

Source : POCC

ECCENTX2
eccentricity times 2 
Datatype: REAL*8              
Units:    NONE
Used in model of HST orbit. See ECCENTRY to get eccentricity by itself. This is a parameter of the flight software model of the HST orbit.

Source : POCC

EPCHTIME
epoch time of parameters since 1/1/85 
Datatype: REAL*8              
Units:    SEC
Number of seconds since 1/1/85 for use of orbit model parameters. A parameter of the flight software model of the HST orbit.

Source : POCC

ESQDX5D2
eccentricity squared times 5/2 
Datatype: REAL*8              
Units:    NONE
Used in model of HST orbit. See ECCENTRY to get eccentricity by itself. This is a parameter of the flight software model of the HST orbit.

Source : POCC

FDMEANAN
1st derivative coef for mean anomaly 
Datatype: REAL*8              
Units:    REV/SEC
In a Taylor expansion of mean anomaly as a polynomial in time, this is the coefficient for the term that is linear in time. Used in model of HST orbit. This is a parameter of the flight software model of the HST orbit.

Source : POCC

HSTHORB
half the duration of the ST orbit 
Datatype: REAL*8              
Units:    SEC
Orbital element for model of HST orbit. A parameter of the flight software model of the HST orbit.

Source : POCC

MEANANOM
mean anomaly 
Datatype: REAL*8              
Units:    REV
In a Taylor expansion of mean anomaly as a polynomial in time, this is the constant term. Used in model of HST orbit. This is a parameter of the flight software model of the HST orbit.

Source : POCC

OBSSTRTT
predicted obs. start time sinse 1/1/85 
Datatype: REAL*8              
Units:    SEC
This is the predicted start time PSTRTIME given in seconds since 1/1/80 converted to seconds since 1/1/85.

Source : POCC

RASCASCN
right ascension of ascending node 
Datatype: REAL*8              
Units:    REV
The right ascension of the line of intersection of the orbital plane and the equatorial plane in the direction of the ascending node. A parameter of the flight software model of the HST orbit.

Source : POCC

RCARGPER
rate change of argument of perigee 
Datatype: REAL*8              
Units:    REV/SEC
A parameter of the flight software model of the HST orbit.

Source : POCC

RCASCNRD
rt chge right ascension ascend node in radians 
Datatype: REAL*8              
Units:    RADS/SEC
A parameter of the flight software model of the HST orbit.

Source : POCC

RCASCNRV
rt chge right ascension ascend node in revolutions 
Datatype: REAL*8              
Units:    REVS/SEC
A parameter of the flight software model of the HST orbit.

Source : POCC

SDMA3SQ
3 * (SDMEANAN**2) 
Datatype: REAL*8              
Units:    (REV/SEC/SEC)**2
See SDMEANAN. A parameter of the flight software model of the HST orbit.

Source : POCC

SDMEANAN
2nd deriv coef for mean anomaly 
Datatype: REAL*8              
Units:    REVS/SEC/SEC
In a Taylor expansion of mean anomaly as a polynomial in time, this is the coefficient for the term that is quadratic in time. A parameter of the flight software model of the HST orbit.

Source : POCC

SEMILREC
semi-latus rectum 
Datatype: REAL*8              
Units:    METERS
An orbital element related to the semi-major axis. It half the width of the ellipse at one of its foci. It is equal to the semi-major axis times the difference of one minus the square of the eccentricity. A parameter of the flight software model of the HST orbit.

Source : POCC

SINEINCL
sine of inclination 
Datatype: REAL*8              
Units:
A parameter of the flight software model of the HST orbit.

Source : POCC

TIMEFFEC
time parameters took effect since 1/1/85 
Datatype: REAL*8              
Units:    SEC
The orbit model was used on HST since this time.

Source : POCC

HST Keyword Dictionary: 14-APR-94: (rose@stsci.edu)