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					    Status of the SCS

Lessions learned during the test phase
                   &
Things to know for future users

                             Potsdam, 28.04.04
                                     T. Granzer
  Tested & Confirmed
 Communication with Telescope & Adapter
 Proof of concept: Sequencing
  • Correct timing of a simple observing sequence

 Proof of concept: Scheduling
  • Correct target selection from a small target pool

 Proof of concept: Error handling
  • Identification & recovery of telescope and
  adapter errors
Sequence definition, details:

XML-based sequence description.
Parallel and sequential execution possible.
Target data filled in at run-time.
Correct handling of unexpected delays.
Errors occurring can alter the sequence.
               1    <Sequence type="single">
Pure           2     <Step>                          Reference to target type
sequential                             ...
                8     <Task id="move">
execution       9      <Condition>Task_open &AND; telescope_finished</Condition>
               10      <Command id="main">MOVE_TELESCOPE</Command>
               11      <Complete>DONE_MOVE_TELESCOPE:main</Complete>
Parallel       12      </Task>
execution      13
               14
                      <Task id="find">
                       <Condition>on_group &AND; adapter_finished</Condition>
allowed        15      <Command id="main">FIND_ADAPTER</Command>
               16      <Complete>DONE_FIND_ADAPTER:main</Complete>
               17     </Task>
               18     <Task id="acquire">
Requirement    19      <Condition>
to commence    20       DONE_MOVE_TELESCOPE:main &AND; DONE_FIND_ADAPTER:main#1000
task           21
               22
                       </Condition>
                       <Command id="main">ACQUIRE_ADAPTER</Command>
               23      <Complete>DONE_ACQUIRE_ADAPTER:main</Complete>
               24     </Task>

This task is   25    </Step>
                                       ...                           From target
finished       34    <Step>                                          definition
               35     <Task id="select">
               36      <Condition>Task_guide</Condition>
               37      <Change>set1</Change>
Update         38      <Complete>Setup=="set1"</Complete>
internal       39     </Task>
               40     <Task id="wavelength">
variables      41      <Condition>spectrograph_wavelength != Wavelength</Condition>
               42      <Command id="set1">SELECT_WAVELENGTH_ADAPTER</Command>
               43      <Complete>
               44        DONE_SELECT_WAVELENGTH_ADAPTER:set1 &OR;
               45        spectrograph_wavelength == Wavelength
               46      </Complete>
Target definition, details:

 XML-based target description.
 Observing constraints might be
added.
 Instrumentation requirements must
be specified.
 Astrometric target data are filled in
from the Tycho-II database.
                    1    <Object type="single" access="enabled">

Defines command     2
                    3
                          <Target>HD 12545</Target>
                          <Select>
sequence            4      <Priority>10</Priority>
                    5      <Requires>roofopen &AND; goodweather</Requires>
                                             ...
Boolean condition   14     <Constraint>
required for        15      <Parameter>SiderealTime</Parameter>
                    16      <From>10.</From>
observation         17      <To>190.</To>
                                                               Additional
                    18     </Constraint>
                    19     <Merit>                             condition
                    20                                         constraints
                            <Timeslot class=“stella.xml.OneObservationMerit”></Timeslot>
Abort handling      21       <Gain class=“stella.xml.ConstantMerit”></Gain>
                    22     </Merit>
                    23     <Abort delay="1800000">
                    24      <Retry>3</Retry>                   Database-
                    25     </Abort>                            resolvable
                    26
                    27
                          </Select>
                          <Star id="main">
                                                               star name
                    28     <General>
                    29      <Name>HD 12545</Name>
                    30     </General>
Required for        31     <Instrument id="set1">
                    32      <Wavelength class="java.lang.Double">6500</Wavelength>
sequencing          33      <Exposuretime class="java.lang.Double">1800</Exposuretime>
                    34      <Buffer>0</Buffer>
                    35      <Fiber>50</Fiber>
                    36     </Instrument>
                    37     <Guiding>
                    38      <Method>Beamsplitter</Method>
                    39      <Filter>clear</Filter>
                    40     </Guiding>
                                             ...
                    60    </Star>
                    61   </Object>
         Scheduling
Dispatch scheduling:

      Target allowed from user side?
      Target observable?

         Evaluate a merit function:
              m(t )   ts j (t )   gi (t )
                        j           i


      Pick target with highest merit
     Target observable?
                                                   Unique
            <Constraint>
                                                   variable
                                                   name
             <Parameter>SolZ</Parameter>
             <Min>100.0</Min>
            </Constraint>

Parameter
            <Constraint>
             <Parameter>Seeing</Parameter>            All Constraints
range
required
             <Max>2.0</Max>
            </Constraint>                             must be
            <Constraint>
             <Parameter>SiderealTime</Parameter>      satisfied at the
             <From>10.</From>
             <To>190.</To>                            given moment
            </Constraint>



  Parameters: AltTarget, AzTarget, Airmass, Elongation, SolZ,
  MoonDistance, MoonHeight, MoonPhase, Seeing, TauTarget,
  SiderealTime, JD, etc.
   Timeslots & Gains:

Combination of proper merits crucial.
Different observing programs require
different merits.
Fixed priority levels to discriminate
importance.
Time-variable merits to achieve optimal data
quality.
    Survey Targets:
Limit number of successful observations:
  ObservationMerit



Optimize target selection:
 AirmassMerit
 WindowMerit
   Periodic Targets:
Specify Period:
 EvenlySpacedMerit
 ForcedTimeoutMerit




Specify Phase Coverage:
 PhaseCoherentMerit
     Targets of
     Opportunity
Can intercept current target
May be combined with a TerminalMerit
            User fairness:
Global UserMerit imposed on ALL targets:




  Parameter tuning extremely important
      Supplying targets:

            SCS

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             Group of operators

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     Users                ToO

				
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