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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ALIASi
synonym for target name 
Datatype: CHARACTER*30        
Units:    N/A
In addition to the catalog name, a target should be assigned at most two 'common names', or aliases. These might include the Bayer (Greek-letter) designation or Flamsteed number with the standard three-letter constellation abbreviation (eg, ZETA-CAP, 22VUL), the Bright Star Catalog number (eg, HR5270), or other names, if they exist (eg, CYG-X1, BARNARDS-STAR, PROXIMA-CEN). Star clusters, nebulae, galaxies, and clusters of galaxies should be assigned commonly used names (eg, HYADES, OMEGA-CEN, CRAB-NEBULA, ABELL63, COMA-CLUSTER) or Messier numbers (eg, M13, M31, M67).

Source : PEP

ANG_SIDE
angle between sides of parallelogram 
Datatype: REAL*8              
Units:    DEGREES
angle, about the beginning of the first scan, from the direction of the first scan to the side of the scan parallogram. precision). This angle is measured clockwise from East towards North. Note: this may be the only clockwise angle in SOGS, but it is the definition required in the SMS.

Source : PEP

APER_k
instrument aperture 
Datatype: CHARACTER*15        
Units:    NAME
Aperture for each data group k.

Source : PODPS

CMD_EXP
commanded time per exposure (from TRANS) 
Datatype: REAL*4              
Units:    SECONDS
This is the exposure time determined by TRANS from the proposal.

Source : TRANS

COL_B_V
expected B-V color 
Datatype: REAL*4              
Units:    relative magnitude
The color of the target expressed as the difference (B - V), where B and V are the band magnitudes in the Johnson color system.

Source : PEP

COL_U_B
expected U-B color 
Datatype: REAL*4              
Units:    relative magnitude
The color of the target expressed as the difference (U - B), where U and B are the band magnitudes in the Johnson color system.

Source : PEP

COL_V_R
expected V-R color 
Datatype: REAL*4              
Units:    relative magnitude
The color of the target expressed as the difference (V - R), where V and R are the band magnitudes in the Johnson color system.

Source : PEP

CONFIG
proposed instrument configuration 
Datatype: CHARACTER*15        
Units:    N/A
This is the same value as the proposal. Examples: WFPC2 or FOC/96

Source : PEP

DEC_PROP
target declination from proposal 
Datatype: REAL*8              
Units:    DEGREES
This is the from the target position supplied in the proposal without precession to equinox J2000 or application of proper motion data.

Source : PEP

DWELL_LN
dwell pts/line for scan pointing (1-99,0 if NA) 
Datatype: INTEGER*4           
Units:    COUNTS
This is non-zero only if this is observation occurs in a dwell scan, otherwise equal to zero.

Source : PEP

DWELL_TM
wait time (duration) at each dwell point 
Datatype: REAL*8              
Units:    SEC
This is non-zero only if this is observation occurs in a dwell scan, otherwise equal to zero.

Source : TRANS

EXTNCT_V
extinction in V 
Datatype: REAL*4              
Units:    relative magnitude
The increase in magnitude due to opacity in the V band.

Source : PEP

E_B_V
extinction in B - V 
Datatype: REAL*4              
Units:    relative magnitude
The color excess due to scattering expressed as B minus V magnitude change.

Source : PEP

MAG_B
expected B Magnitude 
Datatype: REAL*4              
Units:    magnitude
Magnitude in the B-band of the Johnson system.

Source : PEP

MAG_R
expected R Magnitude 
Datatype: REAL*4              
Units:    magnitude
Magnitude in the R-band of the Johnson system.

Source : PEP

MAG_U
expected U Magnitude 
Datatype: REAL*4              
Units:    magnitude
Magnitude in the U-band of the Johnson system.

Source : PEP

MAG_V
expected V Magnitude 
Datatype: REAL*4              
Units:    magnitude
Magnitude in the V-band of the Johnson system.

Source : PEP

MT_LVi_k
moving target information 
Datatype: CHARACTER*68        
Units:    N/A
Proposer comments on moving targets (i=1..3, k=1..5). Extracted directly from the pepsi/sogs relation qtcomments. The index i indicates level and the index k indicates comment line number.

Source : PEP

MU_DEC
target proper motion from proposal in DEC 
Datatype: REAL*8              
Units:    DEGREES/YEAR
The value from the proposal is converted from arcsecs/yesr to degrees/year.

Source : PEP

MU_EPOCH
epoch of proper motion from proposal 
Datatype: CHARACTER*07        
Units:    Julian or Besselian
Date for position and proper motion data. Example: J2000.0 or B1950.0.

Source : PEP

MU_RA
target proper motion from proposal in RA 
Datatype: REAL*8              
Units:    DEGREES/YEAR
The value from the proposal is converted from arcsecs/yesr to degrees/year. The angular motion is along the great circle that is perpendicular to the line of constant RA at the target an the MU_EPOCH.

Source : PEP

NO_LINES
number of lines per scan (1-99,0 if NA) 
Datatype: INTEGER*4           
Units:    COUNT
If the observation occurs during a spatial scan this value will be supplied. The value is taken from the Scan Parameters of the proposal instructions or it is implied by certain target acquisition modes.

Source : PEP or TRANS

OPMODE
proposed operation mode 
Datatype: CHARACTER*15        
Units:    N/A
For each CONFIG there is at least one operation mode. The valid modes depend on the particular CONFIG.

Source : PEP

PARALLAX
target parallax from proposal 
Datatype: REAL*8              
Units:    ARCSECS
The target parallax in arcsec is the maximum change in direction of a celestrial object which results from the change from heliocentric to geocentric coordinate systems. (default = zero). The actual change at the epoch of observation is provided in the keyword ANNPARRA.

Source : PEP

PARENTID
PEP proposal identifier of the parent proposal 
Datatype: INTEGER*4           
Units:    N/A
This is the proposal_id of a previosly approved proposal for a multi-cycle program. This value is zero unless this observation is from a proposal that part of a multi-cycle program.

Source : PEP

PEQUINOX
equinox of coordinate system from proposal 
Datatype: CHARACTER*07        
Units:    Julian or Bessel yea
This value defines the type and epoch of the coordinate system used to specify the target position. The preferred system is J2000.0. Specifications for other coordinates will be precessed and converted to J2000.0 which is the system used to point the telescope.

Source : PEP

RAD_VEL
target radial velocity from proposal 
Datatype: REAL*8              
Units:    KM/SEC
Velocity of a star along the line of sight of an observer.

Source : PEP

RA_PROP
target right ascension from proposal 
Datatype: REAL*8              
Units:    DEGREES
This is the from the target position supplied in the proposal without precession to equinox J2000 or application of proper motion data.

Source : PEP

REDSHIFT
target redshift from proposal 
Datatype: REAL*8              
Units:    wavelength ratio
The fractional increase in wavelength due to Doppler shift, usually denoted as Z.

Source : PEP

SCAN_ANG
position angle of scan line 
Datatype: REAL*8              
Units:    DEGREES
When SCAN_COR indicates a celestial frame scan, this is the counterclockwise angle, about the beginning of the first scan, from north at the target to the direction of the first scan. When SCAN_COR indicates a vehicle frame scan, this is the counterclockwise angle from the positive V3-axis to the direction of the first scan. This is not the definition in the proposal instructions where the direction of the angle for vehicle frame scans depends of the parity of the SI X,Y coordinate system.

Source : TRANS

SCAN_COR
scan coordinate frame of ref: celestial,vehicle 
Datatype: CHARACTER*1         
Units:    N/A
C = celestial frame (RA-DEC), V = vehicle (V2V3). Used to determine meaning of SCAN_ANG.

Source : PEP

SCAN_LEN
scan length 
Datatype: REAL*8              
Units:    ARCSEC
Continuous scan line length or the distance between the first and last point of the first line.

Source : PEP

SCAN_RAT
commanded rate of the line scan 
Datatype: REAL*8              
Units:    ARCSEC/SEC
Only meaningful for continuous spatail scans. This value is calculate by TRANS based on exposures times and overheads or set by proposer for SINGLE-EXP scans.

Source : PEP or TRANS

SCAN_TYP
C:bostrophidon; D:'C'with dwell; N:not applicable 
Datatype: CHARACTER*1         
Units:    N/A
C is a continuous scan and D is a dwell scan. For multiple line scans the direction of scan reverses for each line (like oxen turning when plowing a field). N indicates no scan.

Source : PEP

SCAN_WID
scan width 
Datatype: REAL*8              
Units:    ARCSEC
The separation from the first to the last scan line along the direction ANG_SIDE from the first scan line. Always zero when NO_LINES is one.

Source : PEP

SPEC_i
spectral element 
Datatype: CHARACTER*20        
Units:    N/A
Spectral elements include filters, gratings, prisms, and mirrors. More than one spectral element may be specified for an observation. The allowed values depend on the instrument.

Source : PEP

SP_TYPE
target spectral type from proposal 
Datatype: CHARACTER*15        
Units:    N/A
Spectral type amd luminosity class, used for target description.

Source : PEP

SURF_B
expected B surface brightness 
Datatype: REAL*4              
Units:    mag/asec**2
The broadband surface brightness for the Johnson B band.

Source : PEP

SURF_R
expected R surface brightness 
Datatype: REAL*4              
Units:    mag/asec**2
The broadband surface brightness for the Johnson R band.

Source : PEP

SURF_U
expected U surface brightness 
Datatype: REAL*4              
Units:    mag/asec**2
The broadband surface brightness for the Johnson U band.

Source : PEP

SURF_V
expected V surface brightness 
Datatype: REAL*4              
Units:    mag/asec**2
The broadband surface brightness for the Johnson V band.

Source : PEP

TARDESCR
target description 
Datatype: CHARACTER*68        
Units:    N/A
This description line contains the target catagories and keywords that are separately provided in the keywords TARGCAT TARGCAT

Source : PEP

TARGCAT
first target category 
Datatype: CHARACTER*24        
Units:    N/A                 
		STAR                   Galactic stellar object                                
		STAR CLUSTER           Galactic star cluster, group, or association           
		INTERSTELLAR MEDIUM    Galactic gas or dust                                   
		EXT-STAR               Star in an external galaxy                             
		EXT-CLUSTER            Star cluster in an external galaxy                     
		EXT-MEDIUM             Interstellar medium in an external galaxy              
		GALAXY                 Galaxy, AGN, or QSO                                    
		GALAXY CLUSTER         Cluster or group of galaxies

Source : PEP

TARGCAT2
second target category 
Datatype: CHARACTER*24        
Units:    N/A
Secondary category using same values as TARGCAT.

Source : PEP

TARKEYi
target key description for targcat 
Datatype: CHARACTER*24        
Units:    N/A
Key description entered by the proposer.

Source : PEP

TAR_TYPE
target type 
Datatype: CHARACTER*1         
Units:    N/A                 
		P = point target,                                                             
		A = area target,                                                              
		G = generic target,                                                           
		M = moving target.
Point targets are fixed targets that may have proper motions specifications. Area targets are regions of the sky and may not have proper motion. Generic targets are used for very general regions for parallel observations only. Moving targets are defined in the solar syatem target list.

Source : TRANS

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