WFC3 Instrument Handbook

1.3	Key Features of WFC3

The optical design of WFC3 features two independent channels, one sensitive at ultraviolet (UV) and optical wavelengths, approximately 200 to 1000 nm (the UVIS channel), and the other sensitive at near-infrared (near-IR) wavelengths, approximately 800 to 1700 nm (the IR channel). A channel-selection mirror directs on-axis light from the HST optical telescope assembly (OTA) to the IR channel, or the mirror can be removed from the beam to allow light to enter the UVIS channel. This means that simultaneous observations with the UVIS and IR detectors are not possible. However, both UVIS and IR observations can be made sequentially, even during the same HST orbit.

The extended wavelength range, combined with high sensitivity, high spatial resolution, large field of view, and a wide selection of spectral elements, makes WFC3 an extremely versatile instrument. Key features of WFC3 include:

•	UVIS channel: two 2kâ4k CCDs; pixel scale 0.04 arcsec/pix; field of view 162â162 arcsec; wavelength range 200-1000 nm; S/N=10 in a 10-hour exposure (F606W filter) for a point source with V=29.2 (ABMAG).

•	IR channel: 1kâ1k HgCdTe array; pixel scale 0.13 arcsec/pix; field of view 136â123 arcsec; wavelength range 800-1700 nm; S/N=10 in a 10-hour exposure (F160W) for a point source with H=27.9 (ABMAG).

•	62 wide-, medium-, and narrow-band filters in the UVIS channel.

•	15 wide-, medium-, and narrow-band filters in the IR channel.

•	1 grism in the UVIS channel, and 2 grisms in the IR channel.

A “White Paper,” prepared by the SOC and the Science IPT, outlines some scientific areas that will especially benefit from the capabilities of WFC3. These include searches for galaxies at redshifts up to z~10; studies of the physics of star formation in distant and nearby galaxies; investigations of resolved stellar populations down to faint levels in the UV, optical, and near-IR; and high-resolution imaging of objects in the solar system. WFC3’s panchromatic capabilities allow investigations of the assembly and evolution of galaxies; star birth, evolution, and death and its relation to the interstellar medium; individual and collective properties of small solar system bodies; and aurorae and meteorology of the outer planets. The White Paper (Stiavelli, M., & O’Connell, R.W., eds., 2000, “Hubble Space Telescope Wide Field Camera 3, Capabilities and Scientific Program”) can be found at:

http://www.stsci.edu/hst/wfc3/documents/published/WFC3-WhitePaper-2001.pdf