NGAO topical discussion:
Observing Efficiency and Uptime Budgets
Telecon Meeting 12/7
D. Le Mignant and E. Johansson
7 Dec. 2006
Attendees; R. Campbell, J. Lyke, E. Gates, M. Perrin
Discussion Outline
•
NG AO background information
– Proposal
– NG AO SEMP and WBS…
•
Our tasks
– Observing Efficiency Budget
– Observing Uptime Budget
•
Current Observing Efficiency and Uptime: words from…
– Keck
– Lick?
– Palomar?
•
Next Generation Definitions for
– Observing efficiency
– Observing Uptime
•
WBS Workscope:
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
2
WBS 3.1.1.11 & 12
• Observing Efficiency:
The purpose of this performance budget is to determine what will be required
to meet the Observing Efficiency requirement. Also, report on the lessons
learned with current LGS AO systems (Keck, Gemini, ESO, etc). A list of
all the items contributing to the loss of LGS AO-corrected integration time
will be produced along with reasonable allocations of the observing
efficiency budget amongst these items.
• Observing Uptime Budget:
The purpose of this performance budget is to determine what will be required
to meeting the observing uptime requirement. This budget is only
intended to cover the NGAO facility and science instruments (and not the
telescope or facility). A list of all the items contributing to downtime will
be compiled along with a distribution of the uptime budget amongst these
items.
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
3
101 nights of Keck II LGS AO ops
since Nov. 04 till Jul. 06
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
4
Keck Overall Efficiency: 101 nights
•
•
•
•
•
Bad weather impact:
a) ~17% nights dome
closed - winter weather
b) ~21% nights impacted by
marginal weather
Laser faults
a) Lost: 2 full and 5 1/2nights
b) 9 nights with ~ 1h lost
AO faults
– Minor time lost yet
present for 50% of
nights
Laser Traffic
~ 2% impact
Overheads
– A BIG chunck!
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
5
Keck Overall Efficiency: overheads
1.
2.
3.
4.
5.
6.
7.
Ref: 2006 SPIE papers and some Keck
internal discussion for K1 LGS AO
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
LGS AO checkout

30min/night
Telescope slew and

pointing
Target ID and centering
LGS AO readiness
5 - 10 min/target
LGS AO optimization
2min per hour on target
Telescope/AO

handshakes
30+ sec per dither
Scientific instrument setup
and readout

Observing strategy
6
Keck Observing Efficiency:
Lessons learned
•
•
Keck NGSAO observing efficiency for nights w/o weather or technical
problems at best vary from 25% (snapshot surveys, Lp and Ms obs)
to 60-80% for deep-exposure science programs.
LGSAO shows roughly the same values, except that it is more
impacted by weather and technical problems
DLM’s conclusions: For a reliable system in good weather conditions, we
are currently mostly limited by
1. Serial (vs parallel) algorithms (DCS /inst/AO) during observations
2. Under-designed telescope pointing and acquisition systems
3. Under-designed AO nodding/dithering hardware and software
4. Under-designed science instrument readout
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
7
LGS AO Downtime
155.43 hours total, from 101 nights of LGS AO
8%
0%
14%
2%
Laser traffic control
Spotters
Space Command
22%
Laser faults
AO faults
54%
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Other faults (inst+tel)
8
Review of Keck II LGS AO uptime statistics
• Major contributors to system downtime:
–
–
–
–
–
–
AO Faults
Laser Faults
Other Faults (instrument + telescope)
Space Command (?)
Spotters (?)
Laser traffic control (?)
• Should all these categories be considered as downtime?
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
9
1. Definitions for Observing Efficiency
(what are we talking about?)
•
Currently: Science instrument open shutter time during dark time, including
science data and calibrations (sky, telluric, photometric, PSF, astrometry,
wavelength) / dark time
– Does not take into account any metric science-data quality -> very difficult to
understand how “observing efficient” an instrument is.
• A future definition for NGAO?
Science instrument open shutter(s) time during dark time delivering sciencequality data
– Each data set is flagged with a science-quality idx
– Good understanding of the “observing efficiency” for each type of science
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
10
2. Definitions for Observing Uptime
(what are we talking about?)
•
Currently: AO system and science instrument up and ready to go
– Does not take into account any instrument performance metric (good calibrations,
image quality, operation efficiency, etc)
• A future definition for NGAO?
Science instrument uptime is when it is ready to collect data in support of the
science program.
– Uptime is the opposite of downtime!
– Downtime includes any time (under adequate weather conditions) not spent on
collecting data in support of the science operations.
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
11
Observing efficiency work plan
•
Lessons learned
–
–
•
Provide spreadsheet to science and technical team to help build the efficiency
budget
–
–
•
Collect experience from other LGS AO systems (Palomar, Gemini, Lick, ESO) and a complex
non-AO MOS instrument
Summarize, analyze and understand main factors
Look into big terms per science per sub-system
Circulate a first phase of requirements
Anyone welcome to work on this
–
–
–
–
Need observing experience with other AO/instrument
Need experience with high-level software
Need new ideas to break limitations of current observing paradigms
All need to work fast and efficiently (100 hours total!!)
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
12
Observing efficiency budget
•
Built for each science use case
– Include all observing steps: target acquisition, ID & centering; dithering;
science readout and reductions; dithering; command parsing and decision
making process; calibrations; etc
•
Should assume a 100% core hardware/software reliability? Why separate
Uptime and Obs. Efficiency?
•
Should look into other lost-time statistics (weather, technical, laser traffic)
•
Should look into benefits of:
– Observing planning GUI and simulation tools
– Calibration units and auxiliary systems/data during observing (seeing,
photometry, air-glow monitoring?)
– Other possible impact on science-quality data (cirrus, centering stability)
– System monitoring and recovery to optimize system uptime?
– etc
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
13
Roadmap to an uptime budget
•
Review Keck AO statistics
– Currently have LGS AO stats
– Looking for NGS AO stats
• If not currently summarized, derive from Metrics database
•
•
Attempt to get uptime statistics from other institutions
Remove outliers
– Failures with large downtimes that can be avoided in NGAO, e.g.:
• K2 Laser timing board failure with no spares
• K2 WFC crashes
• K2 Laser failures may not apply to NGAO laser(s)
•
•
Use remaining statistics as a starting point for a budget
Iterate and fine tune
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
14
Conclusions
• Not all current Keck failures/downtime will map directly to NGAO
• Primary downtime drivers will be laser and AO system reliability
• Need to break down AO and Laser faults into finer granularity to
draw more and better conclusions
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
15