Instrumentation on OIR Large Telescopes – A Case Study S. R. Kulkarni Caltech 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 – 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 ……