INTRODUCTION

The Preliminary Observing Timeline Report (POTR or "weekly timeline")
lists the planned HST observations for a given interval.  The timeline
generally begins on Monday and usually covers 1 week.

The report is usually generated about 17 days prior to the beginning
of a week's observations. Observations on this report will usually be
executed, but problems with the spacecraft, scientific instruments,
communications contacts or other events beyond our control may disrupt
the timeline. A Target of Opportunity observation may also disrupt the
timeline.

The report is 132 columns wide.

REPORT HEADER

The report header lists the date the report was generated and the SMS
identifier. The SMS (Science Mission Specification) is a detailed
description of the HST's activities and uniquely identifies a specific
timeline.

The SMS name is of the form YYDOYVVV, where YY is the year, DOY is the
day of the year of the first day in the timeline and VVV is the
version (the version number is not significant).

The report header also lists the start and end dates of the timeline.


REPORT FIELD DESCRIPTIONS

A "Scheduling Unit" (SU) is equivalent to a visit in RPS2.

Scheduling Unit
Begin UT                Earliest start time in YYYY DOY HH:MM:SS for this SU.
End UT                  Latest end time in HH:MM:SS for this SU.

SU ID                   Scheduling Unit Identifier => pppppss:vv
                        where:  ppppp = proposal ID
                                ss = SU number for that proposal (base 36)
                                vv = version number of the SU (usually 01)

The times used in the Weekly Timeline are the scheduling unit (SU) times. 
Observations belonging to the same SU will have the same SU begin and end
times.  Each observation in the SU will have a separate entry in the report. 

Principal Investigat    1st 10 characters of the Principal
                        Investigator's last name

Exp #                   Exposure number this observation in the form VV-EEE
                        where VV is the visit (SU) number
                        and EEE is ???

Target                  1st 10 characters of target name

Science Instrument      Main SI used by this observation

Mode                    SI Operating Mode used by this observation

Apertures               Aperture(s) (up to 4) associated with this observation 

Spectral Elements       Filters/gratings (up to 4) associated with this 
                        observation

Exposure Time           Exposure time in seconds

The next 3 columns are identifiers used by the scheduling software:

OB                      Observation Set ID
                        (An obset is generally one or more alignments that can 
                        use the same Guide Star(s) or Pointing Control 
                        System mode

AL                      Alignment ID
                        (An alignment is generally one or more exposures, done 
                         back to back, with the same telescope pointing)

EX                      Exposure ID
                        (An exposure is essentially one instrument operation.
                         Exposure IDs are different than Proposal Logsheet
                         Line numbers.)

Note: SU, Obset, Alignment and Exposure IDs are base 36 (01, 02..., 09,
0A, 0B, ..., 0Z, 10, ...)

updated 2/13/1997 by Glenn Miller, miller@stsci.edu