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Pre-Observing Observing Post-Observing
Follow this link for information about pre-observing activities: proposal preparation, mask design and submission, pre-run activities, etc. Follow this link for information about your observing run: instrument and telescope setups, scripts, software, procedures, etc. Follow this link for information about your post-observing activities: backups, comment forms, data reduction, etc.
Troubleshooting Technical Pages Index
Trouble Shooting pages and links. Portal to the LRIS technical pages: for the initiated only! A listing of the instrument pages.
The Low Resolution Imaging Spectrometer (LRIS) is a visible-wavelength imaging and spectroscopy instrument commissioned in 1993 and operating at the Cassegrain focus of Keck I.

LRIS was built at Caltech under the supervision of Bev Oke and Judy Cohen. Later James McCarthy and Chuck Steidel took responsibility for adding the blue side.

Reference paper: "The Keck Low Resolution Imaging Spectrometer", Oke, J.B., et al.. 1995, PASP, 107, 375. Most recently, the red side detector was upgraded and documented in "The low-resolution imaging spectrograph red channel CCD upgrade: fully depleted, high-resistivity CCDs for Keck", Rockosi et al.. 2010 SPIE 7735 26.

Beamsplitters separate the light between two arms. The red and blue cameras may be operated simultaneously, and together they may acquire spectra covering a 3200-10,000 Angstroms wavelength range.

The field of view in both modes of operation is 6×7.8 arcmin. The red camera uses a mosaic of two LBNL 2k x 4k fully depleted, high resistivity CCD detectors with a pixel scale of 0.135 "/pixel. The blue camera has a mosaic of 2 2Kx4K Marconi CCDs and the pixel scale is 0.135 "/pixel. The standard imaging filters include the UBVGRI passbands plus a small number of narrowband imaging filters.

Spectroscopy can be performed using a standard complement of longslits of various widths, or in multi-object mode, by using designed slitmasks which are milled on-site. An assortment of gratings (red side) and grisms (blue side) yield resolutions ranging from R=300-5,000, with peak system efficiencies of ~50%.

An optional polarimeter module enables spectropolarimetry.

Click on the map to go to the specific specs pages

Below is an example MOS data product. The image on the left is of a globular cluster. Red rectangles mark the location of the slits for the designed mask. The spectra on the right is the data product output from LRIS. Within each spectra there are verticle lines where the night sky is bright and a horizontal line that is the objects spectrum. The dashed line is the imaging FOV of the LRIS Red Detector.