1. JWST calibration requirements Harald Kuntschner

2. JWST - an overview NIRCam –0.6-5 microns –FoV: 2.16x4.4 arcmin (0.0317” for short band and 0.0648” for long band) NIRSpec (MOS) –~0.8-5 microns –R=100, 1000 & 3000; FoV: 3.2x3.4 arcmin; slit width: 200mas

3. JWST cont. MIRI –5-27 microns –Imager: FoV 1.3x1.3 arcmin; R=100 spec. from 5-10 micron –IFU Spectroscopy: 3”x3” - 7”x7” with 0.2” sampling; R=3000

4. JWST sensitivity 5m5m

5. Main calibration goals Very good cross-instrument calibration on JWST (astrometric, spec, phot and wavelength) Tight link to HST calibration (and other space instruments) Tight link between ground and space based observations

6. Calibration needs (or wishes!) Ground based photometric standard stars from 0.6- 27 microns (matching closely the on board instrument filters, and FoV of NIRCam, MIRI) Ground based spectrophotometric standard stars with well know flux from 0.6-27 micron; matching the resolutions up to R=3000; Key requirement: model atmospheres Ground based, accurate astrometric fields suitable to FoV and spatial resolution Astronomical wavelength standards … For all of the above we need appropriate magnitude range

7. Calibration wishes cont. Need good all sky coverage (need northern partner observatory!) since it is expensive to move JWST. Long duration (~100,000.0 sec) programs on one location foreseen. ESO can offer: –ISAAC, VISTA, VISIR, CRIRES (,FORSes)

8. NIRSpec shutters We expect complicated spectral behavior Need very good calibrators up to R=1000 Target acquisition demands high astrometric accuracy.

9. Specphot stars Optical/NIR paper: Bohlin et al. (2001) Need smooth specphot stds and model atmospheres! ABmag~=8-12 EG131 “typical” flux std

10. Conclusions JWST demands will drive some of the ground based instruments to the limit. Can we modify and expand ESO instrument calibration programs such as to provide JWST with a calibration basis?