Transcript PowerPoint Presentation Template

Science Concept for
Additional Functionality in
the Mosaic Planning Tool
Jeff Valenti
Current Mosaic Tool in APT
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Mosaic Pattern Definition in APT
Initial mosaic definition
Specify tiles per row, row overlap, row shift
Specify tiles per column, column overlap, column shift
Specify orientation
Customize a mosaic
Shift tiles
Rotate tiles (may imply different scheduling window)
Delete tiles
Aladin provides a visual interface
[ Initially delivered in APT 20.4, Oct 2012 ]
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Two Motivations for Additional Functionality
Usability
Users typically want to map a specific region of the sky,
regardless of orient. Existing implementation changes sky
coverage as orient changes. [Jen Lotz]
Assessing guide star availability at different orients is
tedious with current design
Scheduling flexibility
Mosaics are specified at a fixed orient, which implies a
narrow scheduling window as one approaches the pole.
The SOC would like to be able to schedule or reschedule
mosaics without additional input from the observer.
Existing plan is to assign users a new orient and wait for
them to submit a revised mosaic specification. That is fine
if relatively few mosaics need to be updated.
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Mosaic Usage in the SODRM 2012
SODRM 2012 analysis
Caveat: May not be fully representative of actual mission
Over a third of observatory time allocated to mosaics
53% of NIRCam time is mosaics
71% of MIRI time is mosaics
Imaging and IFU mosaics
May be difficult to initially schedule (and in some
cases reschedule) a large number of mosaics with
fixed orients
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Proposed Mosaic Tool Features
Automatically place tiles for an assumed orient
Enable user to define a region of interest on the sky
Enable user to define points that must not be imaged
Proof of concept algorithm does a good job placing tiles
Explore feasibility as a function of orient
Assess guide star availability for all tiles at all orients
Determine fixed number of tiles for any orient
Enable change of orient without new observer input
Simplifies operations, perhaps significantly
See JWST-STScI-003431 by Soderblom et al. (2013)
“Recommendations for user tools to support mosaics with JWST”
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Proof of Concept Code
[ show movie ]
A region is a bounding polygon with optional holes
Simple algorithm
Try to cover region with {rows, columns} of tiles
Each {row, column} can have a different number of tiles
Each {row, column} can have a different offset
For each orient, choose whichever uses fewest tiles
Two passes in the proposal phase
Pass 1 – find number of tiles to cover entire region
Pass 2 – fixed number of tiles, measure coverage
User indicates orients when automatic tiling is acceptable
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Next Steps
Explore exception handling
Handle tiles with inadequate guide star availability
Avoid any user-specified sky points
Develop engineering concept
Challenging for long range plan (LRP) to handle targets
(tiles) with RA and Dec that change with time and jump
when tile configuration changes.
Send comments to Valenti, Blair, Soderblom, ...
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