How to Read a Weekly Timeline
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
The report is 132 columns wide.
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
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.
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.
- 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 next 3 columns are identifiers used by the scheduling software:
- 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 ???
- 1st 10 characters of target name
- Science Instrument
- Main SI used by this observation
- SI Operating Mode used by this observation
- 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
Note: SU, Obset, Alignment and Exposure IDs are base 36 (01, 02..., 09,
0A, 0B, ..., 0Z, 10, ...)
- Observation Set ID
(An obset is generally one or more alignments that can
use the same Guide Star(s) or Pointing Control
- Alignment ID
(An alignment is generally one or more exposures, done
back to back, with the same telescope pointing)
- Exposure ID
(An exposure is essentially one instrument operation.
Exposure IDs are different than Proposal Logsheet
Copyright © 2005 The Association of Universities for
Research in Astronomy, Inc. All Rights Reserved.
Glenn Miller (firstname.lastname@example.org)
Last updated: 10 March 2005