Description
DEIMOS is a general-purpose, faint-object, multi-slit,
double-beam, visible-wavelength imaging spectrograph at the
Nasmyth focus on Keck II. DEIMOS features wide spectral
coverage (up to 5000 � per exposure), high spectral resolution
(down to ~1 �), high throughput, and relatively wide field of
view (81.5 arcmin� field).
Summary
- Type: Dual-beam, multi-object spectrograph
- Wavelength range: optical
- Spectrograph type: slitmask
- Detector array: 8 × ( 4k × 2k) CCDs
- Rotator: built in
- Position: K2 RNAS
- Built at: UCO/Lick
- Optimized for: Surveys of distant galaxies
- GUI control: Dashboard (similar to ESI)
Guider
- PXL 1024×1024 pixel at 0.21 arcsec/px
- Field of view shows
pickoff mirror at bottom 1/3 and slitmask on top 2/3
- Slow readout like ESI
- Displays significant pattern noise in 2×2 binning
readout mode.
- Get good reflection off slitmasks; guiding on slitmask
OK
- TV guider flexure is significant
Rotator
- Entire instrument rotates
- Limits of rotation are -330° < ROTPPOSN <
+400° (two complete revs)
- Slew speed is about 2m 15s per 1 revolution
- Tracking excellent through zenith
Pointing Origins
- See also: KSD40-style drawing of
focal plane
- REF is on center of pickoff mirror (AUTOFOC here)
- SLIT is centered on the longslit position
- IMAGE is directly above the slit (send faint longslit
targets here)
- DEIMOS is at slitmask center (send slitmask centers here)
- TVCENTER is at center of guider (512,512)
- MIRA will be used for telescope focus
Focus
- AUTOFOC and MIRA work well
- Secondary tilt compensations should be minimal
- Should
not need to focus as often as with LRIS
- Probably no
telescope focus difference between imaging and spectroscopy modes
Eavesdropping
- OA can run DEIMOS dashboard from DCS GUI
See Also