Instrumentation on OIR Large Telescopes – A Case Study

S. R. KulkarniCaltech Optical Observatories

• Workhorse Instruments– Optical Imagers & Spectrographs– NIR Imagers & Spectrographs and so on

• Specialized Instruments– Polarimeters, Rapid spectroscopy, ..

• Adaptive Optics & related instruments• “Mega” instruments– Very powerful capabilities (e.g. PFS, GPI, NGAO)

Motivation

• Cost of workhorse instruments is increasing much faster than inflation

• The cost of Adaptive Optics facility (let alone instruments) is significant

• The cost of mega instruments is now approaching that of the telescope itself

Issues: Prioritization & Opportunity Costs

• Given a fixed budget how to prioritize instrumentation– New instruments versus Upgrades– Which instruments should be built?

• Mega-instrument– Say cost of a mega instrument is $50M– Per night usage is $50M/N where N=total number of

nights– Inversely the opportunity cost of Mega instruments is

significant both in money and nights

A CASE STUDY: ANALYZE THE OUTPUT OF THE KECK TELESCOPES

Keck Telescopes

• Keck I, commissioned in 1993 [$93M]• Keck II, commissioned in 1996[$73M]• Other than thermal-IR Keck has a complement

of instruments from blue to NIR

The Instruments

• NIRC• NIRC2• NIRSPEC• OSIRIS• MOSFIRE

• LRIS• HIRES• ESI• DEIMOS• KCWI

Keck AO Facility

• We have LGS AO on both telescopes. • NIRC2 is at Keck II• OSIRIS at Keck I• Continuous upgrades (Center Launch, NIR Tip-

tilt, wavefront controller upgrades etc)

Primary data

• Use the publications which are listed on the WM Keck site – http://www2.keck.hawaii.edu/library/keck_papers.html

• This list is due to Peggi Kamisato and Taft Armandroff.

Top papers by citations

LIGHT CURVES

Some Conclusions

• It takes about five years for an instrument to peak

• The usable lifetime of instruments, if not upgraded, is 10 years

• Optical instruments seem to be more productive and have more impact than NIR (with and without AO) instruments

• Upgrades increase the productivity of instruments at very low cost

ARE BUILDERS WELL RECOGNIZED?

COST & VALUE OF A NIGHT

CASE STUDY: THE VERY LARGE ARRAY

Should a new all-sky survey be undertaken by the VLA?

NVSS & FIRST

FIRST NVSS

Survey returns

• NVSS and FIRST started off with linear returns for five years and another decade to reach peak fluxes

• NVSS is returning three times more citations than the typical mix of programs

• A second sky survey is eminently reasonable and should be undertaken rapidly

DISCUSSION FOR THE AUDIENCE

Mega Instruments & Surveys

• Mega-instruments are powerful but also expensive.– eg. HSC, PFS, BigBOSS, GPI, SPHERE

• Once built must be used extensively – Presumably the science returns demand it

• Age of Surveys– Even PTF can keep Palomar and Keck quite busy– Let alone HSC– Let alone GAIA – Let alone planned radio surveys

Lack of Followup telescopes

• Mega-instruments remove telescopes from routine use

• Surveys demand extensive follow up• But no new telescopes are being

contemplated ……