C.1 Observation Log Files

The observation log files share the same rootname as the observation they are associated with, except for the final character, which for observation log files is always a "j" (see Appendix B for more on the names of HST data files). When OMS was installed in October 1994, it initially generated files with the suffixes cmh, cmj, cmi, which contained header information, high time resolution pointing data, and three-second average pointing data, respectively (see Table C.1). OMS observation logs changed to the jih/jid/jif image format after August 1995, at which time the cmi table was renamed jit to keep the naming convention consistent. In the OMS version of August 1995, cmj tables were replaced with a jitter image, which is a two-dimensional histogram of jitter excursions during the observation. The suffixes of the GEIS jitter image are jih for the header and jid for the image data. The jit table accompanies the jitter image. The header file of the image replaces the cmh file but includes the same information with the addition of some image-related keywords.

A detailed description of the observation log files can be found on-line:
http://www.stsci.edu/ftp/instrument_news/Observatory/
obslog/OL_1.html

• rootnamej.cmh: This ASCII header file contains the time interval, the rootname, averages of the pointing and spacecraft jitter, the guiding mode, guide star information, and alert or failure keywords. Figure C.1 shows a representative observation log header file.
• rootnamej.cmj: This table presents the data at the highest time resolution for the telemetry mode in use. It contains the reconstructed pointing, guide star coordinates, derived jitter at the instrument aperture, and guiding-related flags. The intent is: (1) to provide high-time resolution jitter data for deconvolution or for assessing small aperture pointing stability, and (2) to display the slew and tracking anomaly flags with the highest resolution. Table C.2 lists the table column heading, units and a brief definition.
• rootnamej.cmi: This table contains data that were averaged over three-second intervals. It includes the same information as the .cmj table and also includes orbital data (e.g., latitude, longitude, limb angle, magnetic field values, etc.) and instrument-specific items. It is best suited for a quick-look assessment of pointing stability and for studying trends in telescope or instrument performance with orbital environment. Table C.3 lists the table column heading, units and a brief definition.
• rootnamej_cmi/j/h.fits: The above three GEIS files are actually archived as FITS files. They may be worked with as such, or run through the STSDAS task strfits, to convert them.

• rootnamej.jih: This GEIS header file, the analog to the cmh file, contains the time interval, the rootname, averages of the pointing and spacecraft jitter, the guiding mode, guide star information, and alert or failure keywords. Figure C.2 shows a representative observation log header file.
• rootnamej.jid: This GEIS image-a significant enhancement of the old cmj file-presents a two-dimensional histogram of the pointing fluctuations during the observation. You can display it to visualize the spacecraft stability during you observation, and is information for deconvolutions and PSF analyses.
• rootnamej.jit: This table, the analog to the cmi table, contains data that were averaged over three-second intervals. Its content is identical (see Table C.3).
• rootnamej_jif.fits: FITS file that is actually the de-archived product. This file can be converted to the jih/jid GEIS file via the strftis routine.
• rootnamej_jit.fits: The de-archived FITS file corresponding to the jit IRAF table. It can be converted via strfits.

• rootnamej_jif.fits: The de-archived FITS file. Unlike the previous OMS epoch, this FITS file does not bundle a GEIS file and cannot be converted with strfits. This was done to more closely correlate the observation log files with the STIS and NICMOS FITS files with extensions and associations. OMS will normally put all associated observation logs into a single file, to correspond to the associated science exposures. However, if even one science exposure is orphaned (not associated) then an individual observation log FITS file will be produced for every exposure in that association. For a description of STIS and NICMOS association files, see Appendix B. All of the information contained in the old cmh/jih ASCII header is now available as keywords in the FITS files.
• rootnamej_jit.fits: The FITS file containing the table information. The comments for the _jif file apply here as well.

Figure C.1: A Representative .jih or .cmh Header

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SIMPLE  =                    F / data conforms to FITS standard               !

BITPIX  =                   32 / bits per data value                          !

DATATYPE= `INTEGER*4         ` / datatype of the group array                  !

NAXIS   =                    2 / number of data axes                          !

NAXIS1  =                   64 / length of the 1st data axis                  !

NAXIS2  =                   64 / length of the 2nd data axis                  !

GROUPS  =                    T / image is in group format                     !

GCOUNT  =                    1 / number of groups                             !

PCOUNT  =                    0 / number of parameters                         !

PSIZE   =                    0 / bits in the parameter block                  !

OMS_VER = `16.2C             ` / OMS version used to process this observation

PROCTIME= `1994.133:06:24:18.35' / date-time OMS processed observation

                                 / date-times format (yyyy.ddd:hh:mm:ss.ss)

                               / IMAGE PARAMETERS

CRVAL1  =                  0.0 / right ascension of zero-jitter pixel (deg)     

CRVAL2  =                  0.0 / declination of zero-jitter pixel (deg)         

CRPIX1  =                   32 / x-coordinate of zero-jitter pixel              

CRPIX2  =                   32 / y-coordinate of zero-jitter pixel              

CTYPE1  = `RA---TAN          ` / first coordinate type                        

CTYPE2  = `DEC--TAN          ` / second coordinate type                       

CD1_1   =                  0.0 / partial of ra w.r.t. x (deg/pixel)

CD1_2   =                  0.0 / partial of ra w.r.t. y (deg/pixel)

CD2_1   =                  0.0 / partial of dec w.r.t. x (deg/pixel)

CD2_2   =                  0.0 / partial of dec w.r.t. y (deg/pixel)

COORDSYS= `WFPC2             ` / image coordinate system         

XPIXINC =                  2.0 / plate scale along x (mas per pixel)         

YPIXINC =                  2.0 / plate scale along y (mas per pixel)         

PARITY  =                   -1 / parity between V2V3 frame and image frame   

BETA1   =               134.72 / angle from +V3 to image +x (toward +V2)   

BETA2   =               224.72 / angle from +V3 to image +y (toward +V2)   

                               / OBSERVATION DATA                        

PROPOSID=                05233 / PEP proposal identifier                      

PROGRMID= `288               ` / program id (base 36)

OBSET_ID= `02                ` / observation set id

OBSERVTN= `03                ` / observation number (base 36)

TARGNAME= `NGC3379-PO        ` / proposer's target name 

STARTIME= `1994.133:06:24:18.35' / predicted observation window start time 

ENDTIME = `1994.133:06:39:18.35' / predicted observation window end time 

SOGSID  = `U2880203          ` / SOGS observation name                        !

                               / SCIENTIFIC INSTRUMENT DATA              

CONFIG  = `WFPC2             ` / proposed instrument configuration 

PRIMARY = `SINGLE            ` / single, parallel-primary, parallel-secondary

OPERATE = `1994.133:06:22:46.91' / predicted time instr. entered operate mode 

TLMFORM = `PN                ` / telemetry format                               

APERTURE= `UWFALL            ` / aperture name 

APER_V2 =                1.565 / V2 aperture position in vehicle frame (arcsec) 

APER_V3 =                7.534 / V3 aperture position in vehicle frame (arcsec) 

                               / SPACECRAFT DATA                         

ALTITUDE=               593.23 / average altitude during observation (km)       

LOS_SUN =               106.08 / minimum line of sight to Sun (deg)             

LOS_MOON=                77.11 / minimum line of sight to Moon (deg)            

SHADOENT= `1994.133:05:11:29.00' / predicted Earth shadow last entry 

SHADOEXT= `1994.133:05:42:45.00' / predicted Earth shadow last exit

LOS_SCV =                12.46 / minimum line of sight to S/C veloc. (deg)      

LOS_LIMB=                 58.0 / average line of sight to Earth limb (deg)      

                               / BACKGROUND LIGHT                        

ZODMOD  =                 22.3 / zodiacal light - model (V mag/arcsec2)         

EARTHMOD=                 20.2 / peak Earth stray light - model (V mag/arcsec2) 

MOONMOD =                 35.5 / moon stray light - model (V mag/arcsec2)       

GALACTIC=                 -1.0 / diffuse galactic light - model (V mag/arcsec2) 

                               / POINTING CONTROL DATA                   

GUIDECMD= `FINE LOCK         ` / commanded guiding mode                         

GUIDEACT= `FINE LOCK         ` / actual guiding mode at end of GS acquisition   

GSD_ID  = `0084900235        ` / dominant guide star id                         

GSD_RA  =            161.70720 / dominant guide star RA (deg)                   

GSD_DEC =             12.45407 / dominant guide star DEC (deg)                  

GSD_MAG =               12.867 / dominant guide star magnitude                  

GSR_ID  = `0085201189        ` / roll guide star id                             

GSR_RA  =            161.93314 / roll guide star RA (deg)                       

GSR_DEC =             12.78141 / roll guide star DEC (deg)                      

GSR_MAG =               12.977 / roll guide star magnitude                      

GSACQ   = `1994.133:06:31:02.92' / actual time of GS acquisition completion

PREDGSEP=             1420.775 / predicted guide star separation (arcsec)       

ACTGSSEP=             1421.135 / actual guide star separation (arcsec)          

GSSEPRMS=                  3.8 / RMS of guide star separation (milli-arcsec)    

NLOSSES =                    0 / number of loss of lock events                  

LOCKLOSS=                  0.0 / total loss of lock time (sec)                  

NRECENT =                    0 / number of recentering events                   

RECENTR =                  0.0 / total recentering time (sec)                   

                               / LINE OF SIGHT JITTER SUMMARY            

V2_RMS  =                  4.5 / V2 axis RMS (milli-arcsec)                     

V2_P2P  =                 51.6 / V2 axis peak to peak (milli-arcsec)            

V3_RMS  =                 20.9 / V3 axis RMS (milli-arcsec)                     

V3_P2P  =                267.3 / V3 axis peak to peak (milli-arcsec)            

RA_AVG  =            161.85226 / average RA (deg)                               

DEC_AVG =             12.58265 / average dec (deg)                              

ROLL_AVG=            293.01558 / average roll (deg)                             

                               / PROBLEM FLAGS, WARNINGS and STATUS MESSAGES 

                               / (present only if problem exists)

ACQ2FAIL= `                 T' / target acquisition failure                   

GSFAIL  = `DEGRADED          ` / guide star acquisition failure  (*1)

TAPEDROP= `                 T' / possible loss of science data                

TLM_PROB= `                  ` / problem with the engineering telemetry       

TM_GAP  =               404.60 / duration of missing telemetry (sec)          

SLEWING = `                 T' / slewing occurred during this observation     

TAKEDATA= `                 F' / take data flag NOT on throughout observation 

SIPROBnn= `                  ` / problem with specified science instrument (*2) 

END                                                                             

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notes 

*1 - GSFAIL appears only once in a single header file.  

     The following table lists all current possible values for the GSFAIL

     keyword:

     -------------------------------------------------------------

     GSFAIL   |DEGRADED         | / guide star acquisition failure

              |IN PROGR         | / guide star acquisition failure

              |SSLEXP           | / guide star acquisition failure

              |SSLEXS           | / guide star acquisition failure

              |NOLOCK           | / guide star acquisition failure

              |                 |                                 

              |SREXCS?          | / guide star acquisition failure

              |SREXCS1          | / guide star acquisition failure

              |SREXCS2          | / guide star acquisition failure

              |SREXCS3          | / guide star acquisition failure

              |                 |                                 

              |SREXCP?          | / guide star acquisition failure

              |SREXCP1          | / guide star acquisition failure

              |SREXCP2          | / guide star acquisition failure

              |SREXCP3          | / guide star acquisition failure

              |                 |                                 

              |UNKNOWN          | / guide star acquisition failure

              |VEHSAFE          | / guide star acquisition failure

     -------------------------------------------------------------

*2 - The SIPROBnn keywords appear in the header file with nn = 01 - 99.  

     The following table lists all current possible values for the SIPROBnn 

     keyword:

     -------------------------------------------------------------------------

     SIPROBnn |DCF_NUM unchanged| / This observation may not have been taken 

              |FOS Safing!      | / This observation affected when FOS Safed!

              |HRS Safing!      | / This observation affected when HRS Safed!

              |WFII Safing!     | / This observation affected when WFII Safed!

              |FOC Safing!      | / This observation affected when FOC Safed! 

              |Shut             | / FOS aperture door is not Open!            

              |FAILED           | / FGS astrometry target acquisition failed  

     -------------------------------------------------------------------------

Contents of .jit or.cmiTable, Three-Second Averaging

Parameter	Units	Description
seconds	seconds	Time since window start
V2 dom	arcseconds	Dominant FGS V2 coordinate
V3 dom	arcseconds	Dominant FGS V3 coordinate
V2 roll	arcseconds	Roll FGS V2 coordinate
V3 roll	arcseconds	Roll FGS V3 coordinate
SI V2 AVG	arcseconds	Mean jitter in 3 seconds
SI V2 RMS	arcseconds	rms jitter in 3 seconds
SI V2 P2P	arcseconds	Peak jitter in 3 seconds
SI V3 AVG	arcseconds	Mean jitter in 3 seconds
SI V3 RMS	arcseconds	rms jitter in 3 seconds
SI V3 P2P	arcseconds	Peak jitter in 3 seconds
RA	degrees	Right ascension of aperture reference
DEC	degrees	Declination of aperture reference
Roll	degrees	Angle between North and +V3
LimbAng	degrees	Angle between earth limb and target
TermAng	degrees	Angle between terminator and target
LOS_Zenith	degrees	Angle between HST zenith and target
Latitude	degrees	HST subpoint latitude
Longitude	degrees	HST subpoint longitude
Mag V1,V2,V3	degrees	Magnetic field along V1, V2, V3
EarthMod	V Mag/arcsec2	Model earth background light
SI_Specific	-	Special science instrument data
DayNight	0,1 flag	Day (0) or night (1)
Recenter	0,1 flag	Recentering status
TakeData	0,1 flag	Vehicle guiding status
SlewFlag	0,1 flag	Vehicle slewing status