Absorption-line redshifts of galaxies in remote clusters obtained with a sky-subtraction spectrograph using an SIT television detector
A prism spectrograph with an associated SIT television camera, operating as a two-dimensional detector with digital readout, has been used at the 5-m Hale telescope. The system was tested for its ability to subtract the sky spectrum, and was found to produce difference spectra that are essentially photon noise limited. Redshifts of 14 galaxies in clusters with 0.01 ≤ z ≤ 0.4 were obtained, each with exposure times of 90 minutes or less. Nine of the redshifts are new. Redshifts for the remaining five agree with previous values to within the measuring errors. The speed and sky-subtraction capabilities of the instrument are sufficient to begin routine measurement of absorption-line redshifts for remote cluster galaxies in an effort to extend the Hubble diagram.
Additional Information© 1975 American Astronomical Society. Provided by the NASA Astrophysics Data System. Received 1975 January 24. This work was supported in part by the National Science Foundation, under grant GP-364S0X to the Carnegie Institution of Washington.
Published - 1975ApJ___197L__95W.pdf