Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.stsci.edu/institute/stuc/apr07-presentations/Parallels.pdf Дата изменения: Tue Apr 17 22:40:09 2007 Дата индексирования: Sat Dec 22 19:36:24 2007 Кодировка: Поисковые слова: http astrokuban.info astrokuban

Parallels Post-SM4
Ken Sembach STUC Presentation April 13, 2007


Parallels
· · Parallel observations offer a chance to increase the science productivity of HST Operate one or more instruments in conjunction with the prime science instrument
·

"Coordinated" Parallels
Parallel is part of prime science investigation proposed and approved in Phase I Parallel specification is given by GO as part of Phase II proposal
· Parallel and prime exposures/visits are specified together

·

"Pure" Parallels
Parallel is proposed in Phase I as part of standalone parallel science program Parallel specification / description is given by GO in Phase II
· Parallel and (unrelated) prime visits are matched later by STScI

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· ·

Prior to ACS failure, we expected that ACS+WFC3 would be used in parallel frequently.
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Parallel Opportunities

ACS repair would re-enable synergy with WFC3

COS/STIS will probably account for ~30% of prime observing time (~1000 orbits per cycle)
·

For most COS observations, parallels could be scheduled without readout and buffer dump conflicts

COS Prime (Exp 1)

WFC3/UVIS Parallels (Exp 2-5)

· ·

Parallels may also benefit from long STIS observations If ACS is restored, using multiple instruments in parallel at the same time (e.g., WFC3+ACS) results in more buffer conflicts
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A Few More Parallel Examples
COS Prime (Exp 1) ACS/WFC WFC3/UVIS

COS Prime (Exp 1)

ACS/HRC

WFC3/UVIS

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Maximizing Parallel Science
· Coordinated parallels will be allowed/encouraged as usual
· · ·

Relationship of parallels to prime observation is responsibility of GO Matching of exposures done within APT Scheduling is simplified since any changes specified by GO are done with knowledge of impact to parallels (and vice versa) Existing implementation is less efficient than desired
Visits matched late in scheduling process (after primes are scheduled)
· Doesn't always work

·

Pure parallel philosophy is being rethought
·

Rigid visit structure/specification limits scheduling opportunities Long parallel opportunities are difficult to schedule Prioritization and completion of parallel visits are not handled optimally
·

New implementation should improve parallel science return
Treat parallel observations more like primes in terms of completion Match as many parallels to primes as possible Possibly develop parallel LRP (long range plan) to help matching process

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Examples of Possible Parallel Programs
· · · · · · · · Searches for high-z supernovae with WFC3 grism Searches for z > 7 galaxies with WFC3 IR channel WFC3 deep UV fields Cosmic variance (ACS or WFC3) Cluster mosaics, weak lensing on small scales Magellanic cloud narrow band imaging survey Nearby galaxy stellar population studies and so on....

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Parallels - Issues Under Study
· Specification
· · ·

Should GOs specify complete visits (as now) or exposure sets? How do GOs specify observation and program completion requirements? How should GOs prioritize exposures/observations within a program? How and when do we (STScI) best match parallels to primes? What buffer management issues exist? How do we satisfy observation and program completion requirements? Starting position: primes will be unaffected by addition of parallels But may want to do small dithers to improve parallel imaging data
Roll and POS-TARG dither options for COS primes are being studied Possibly dither only between orbits, not within orbits

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Implementation
· · ·

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Impact of parallels on primes
· ·

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Effort Required
·

We are scoping work in various areas
software development, scheduling, program coordination, APT, TRANS, etc.
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