  In preparation for James Webb Space Telescope (JWST), a set of cross
calibration programs with HST and Spitzer for suitable primary photometric
standards and astrometric fields were developed. NICMOS/HST and IRAC/Spitzer
photometry observations of new solar analog standards in NGC 6791 and Melotte
66 were executed. These new photometric standards will provide ~ 5% photometric
precision at V~19 from the near-IR to the mid-IR wavelength range for efficient
on-orbit calibration and measuring of photometric stability of the JWST
complement. For the astrometric calibration, a field in the LMC has been
selected. This field falls within the JWST continuous viewing zone, within 5
degrees from the ecliptic poles, and has the stellar density necessary to
achieve accuracies better than 1 mas with HST/ACS. These independent
observations will play a key role in meeting the mission requirements and will
allow a fast commissioning of the observatory.

Astrophysics