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Overview of UVOT

The UVOT (Roming, et al. 2005, SSRv, 120, 95) is a modified Ritchey-Chrétien telescope with a 30 cm aperture and an f-number of f/12.72. It operates in the wavelength range of 1600-6000 Å, although there is some low-level response in between 6000 Å and 8000 Å. It is mounted on the optical bench with the BAT and the XRT as shown in Figure 8 and co-aligned with the XRT. An 11-position filter wheel houses the UV and optical grisms, a 4-times magnifier, broadband UV and optical filters, a clear ``white-light'' filter, and blocking filter. Photons register on a micro-channel plate intensified charged-coupled device. These can operate in a photon counting mode and are capable of detecting very low light levels. When flown above the atmosphere the UVOT possesses the equivalent sensitivity of a 4 m ground-based telescope, capable of detecting a 22nd magnitude B star in 1000 seconds using the white-light filter. An outline of the UVOT's characteristics can be found in Table 7.

Figure 9: UVOT's placement on the Swift optical bench.
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Table 7: Characteristics of the UVOT.
UVOT Parameter Value
Telescope Modified Ritchey-Chrétien
Aperture 30 cm diameter
f-Number f/12.72
Detector Intensified CCD
Detector Operation Photon Counting
Field of View $17 \times 17$ arcminutes
Detection Elements $256 \times 256$ pixels
Sampling Elements $2048 \times 2048$ pixels after centroiding
Telescope PSF approximately 2.5 arcseconds FWHM
Wavelength Range 1600-6000 Å
Filters 11
Sensitivity B = 22.3 in white light in 1000 s
Virtual Pixel Scale 0.502 arcseconds
Timing Resolution 11.0329 ms
Gain 1.0 count ADU$^{-1}$
Readout Noise 0.0 count s$^{-1}$ pixel$^{-1}$
Dark Current $7 \times 10^{-5}$ count s$^{-1}$ pixel$^{-1}$



next up previous contents
Next: UVOT Description Up: The Ultraviolet/Optical Telescope Previous: The Ultraviolet/Optical Telescope   Contents
Eleonora Troja 2013-09-03