Examples of Synoptic Date Blocking
Targets to be observed on specified dates:
The visit dates of date-specified targets can be controlled with the SYN Dates parameter of the target list. If you wish the
target to be observed on the civil night beginning May 2, 2020 then submit
a target list with the SYN Date set to =20200503 (NOTE the change to UT date).
This lets the RA know that this is the ONLY date that the target
should be observed.
You can further restrict the time of observation by invoking the Azimuth Restriction parameter of the
target list. This instructs the RA to observe
the target ONLY in its east or west track. To help prevent that being
overlooked (as it is an infrequently used feature),
state "East Only" or "West Only" near the beginning of the
Comments field of the target list
Targets to be observed in a strongly structured cadence:
For a situation with e.g. orbital or pulsational phase filling, there are
two approaches. The first first predates the enhanced TSL submission software.
You would have to submit all of the visit window possibilities for each visit,
having first eliminated any visits which are unfeasible by means of the
E.g., if you need one visit on any one of the following UT dates May 2, May 10,
May 15; and two visits on any two of the following UT dates: May 3, May 11,
May 16, and May 23, then create two targets, one single-visit with the SYN Dates entry being
and one double-visit with the SYN Dates entry being
While the potential to submit or retract batteries of date-specific SYN Dates
targets is unlimited, it takes a good deal of PI activity continually to rejig the
target list in such a way, as visits are executed or bypassed, compounded by
size of the program. By this point reconsider whether the automatic phase-blocking
software offers a better solution.
Targets to be observed in a partly structured cadence:
Set the SYN frequency entry in the target list to be
RAND#-# where # are given in days. That sets the strict minimum cadence
interval and a target for the maximum cadence interval.
The RA will add a value within the RAND frequency range to the current
UT date and place that in the SYN Dates entry of the
For example: If we observe a target on 20200301 that has
a SYN frequency of RAND5-10, then the RA will update the
SYN frequency to be >20200306 and the target will be synoptically
blocked until 20200305.
The PI should note that given the competition with other targets, and
the progression of observing conditions and moon phases, there is no
guarantee that the maximum spacing will not be exceeded. However the
RA modified priority tactic increasingly strongly flags synoptics that
overshoot their cadence upper bound, so there is partial feedback. The
use of a minimum frequency of 0 will suggest to the RA that it is fine (but
not required) to observe the target twice in a night (once in the East track
and once in the West track). For targets far in the north or south which only
have 1 track please use a minimum frequency of 1 or contact the RAs for more
Targets to be observed with minimally structured cadence:
Letting the RA observe your targets when the conditions and TAC priorities
warrant, will produce a fairly random sampling cadence within the bounds
set by the annual rate of access to different sidereal times and by
trimester discreteness. You can influence the cadence by explicitly
setting the bounds to the range of target visit dates.
The PI effects this via
the SYN Dates and Comments
entries of the target list. E.g.,
if a target should be observed within the window Mar 1-5 2020, civil date,
then the SYN Dates parameter should be >20200302-20200306 or
>20200302,<20200306. (Note the change to UT date).
Targets with a known periodicity and explicitly intended phase coverage:
For some programs it is desirable to achieve a particular phasing of
observations, with respect to a known periodicity cycle. Examples are:
observing only at selected phases (such as extrema), observing only
away from selected phases (such as avoiding light minima), or observing
so as to approximate a quasi-uniform phase coverage. See the phase-blocking
(phase-filling) software discussion.
Remember: making a target synoptic by invoking any of the abovementioned
parameters will result in the target status being activated only in the
provided date window, and being software-BLOCKED for the entire
trimester duration outside that window.
Last updated: Sun, 05 Aug 2012 03:53:49 -0500 caldwell