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Instrument Design

  • WFC3 Instrument Handbook

    For more detailed descriptions of WFC3's components and behaviors, see the WFC3 Instrument Handbook

Two Channels

Observations with WFC3 can make use of the UVIS or IR Channels, and a channel select mechanism directs incoming light to the desired channel. The light path within WFC3 for both channels is shown in the figure below. The IR light path is drawn in red, and the UVIS light path is drawn in pink.

WFC3 Optical Path

The WFC3 detectors are capable of observing at all wavelengths between 200 - 1700nm. The QE curves for the UVIS and IR detectors are shown below. These curves do not include the effects of HST's OTA, nor WFC3's optics and filters.


Detector QE

Detector Characteristics

IR Channel

Components: Teledyne 1Kx1K HgCdTe detector. MBE-grown, substrate removed.

Total Field of View: 123 x 136 arcsec

Pixel Size: 0.13 arcsec

Nominal Operating Temperature: 145 K

Dark Current: 0.048 e-/sec/pix (median) [See WFC3 IHB, Table 5.1]

Dark Current Tail (% of pixels with Dark Current >0.4 e-/sec/pix): 0.7%

Readnoise: 21 e- (CDS), 12 e- (16-read linear fit) [See WFC3 IHB, Table 5.1]

Full Well: 77,900 e- [See WFC3 IHB, Table 5.1]

UVIS Channel

Components: 2 e2V thinned, backside illuminated, UV optimized 2Kx4K CCDs

Total Field of View: 162 x 162 arcsec

Pixel Size: 0.04 arcsec

Nominal Operating Temperature: -83C

Dark Current: 3 e-/hr/pix (median) [See WFC3 IHB, Table 5.1]

Readnoise: 3.1 e-

Full Well: 63,000 -- 72,000 e- [See WFC3 IHB, Table 5.1]


WFC3's complement of filters cover the entire useful wavelength range dictated by the detectors. Individual plots of filter throughputs are available in the WFC3 Handbook. More information about WFC3 filters can be found on the WFC3 filter page.

The plots below show the total system throughput for all of WFC3's filters.

WFC3 contains a large compliment of filters: 63 in the UVIS channel, and 17 in the IR channel. Actual transmission data for all filters can be found on the WFC3 CDBS ftp site. See the SYNPHOT site for information on how to use these data.

View the full throughput list.


IR Filters

IR Filler Wheel
There are 18 filter slots in the IR channel. Fifteen of them span broad- and medium-band wavelengths that range from 800 to 1900nm. Two are grisms for slitless spectroscopy, and there is one blank position.

UVIS Filters

UVIS Filter Wheels
There are 48 filter slots in the UVIS WF/PC Selectable Optical Filter Assembly (SOFA) wheels. Five of those slots are occupied by "quad filters." Each quad filter contains four different spectral elements. One slot is occupied by a grism for low resolution slitless spectroscopy from about 200 to 400 nm. The other filters have a variety of bandwidths using the WFPC2, Sloan, Washington, and Stromgen photometric systems.


Grism Throughput UV

Grism Throughput IR

WFC3 Filters Slideshow

IR-WideBand (1)
IR-WideBand (2)
IR-Medium Band
IR-Medium Band
IR-Narrow Band
IR-Narrow Band
UVIS - LP Filters
UVIS - Long Pass Filters
UVIS Wide-band Filters
UVIS Wide-band Filters (1)
UVIS Wide-band Filters
UVIS Wide-band Filters (2)
UVIS Medium Filters
UVIS Medium Filters
UVIS Narrow Filters
UVIS Narrow Filters
UVIS Narrow Filters (2)
UVIS Narrow Filters (2)
UVIS Narrow Filters
UVIS Narrow Filters (3)
UVIS Narrow Filters
UVIS Narrow Filters (4)
UVIS Narrow Filters
UVIS Narrow Filters (6)
Last Updated: 01/31/2024


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