A Caltech Library Service

Discovery of a new gravitational lens

Djorgovski, S. and Spinrad, H. (1984) Discovery of a new gravitational lens. Astrophysical Journal, 282 . L1-L4. ISSN 0004-637X. doi:10.1086/184291.

[img] PDF (ADS) - Published Version
See Usage Policy.


Use this Persistent URL to link to this item:


The faint QSO pair 1635 + 267 A + B, discovered in a slitless spectroscopy survey by Weedman (1982), are found to be at practically the same redshift of 1.961 ± 0.003. Their redshift difference, determined with a cross-correlation technique, is found to be (3.2 ± 8.5) x 10^(-4), which corresponds to a rest-frame velocity difference of only (33 ± 86) km s^(-1). This low value and the similarity of the spectra strongly argue that this is another case of a gravitational lens. Deep CCD images do not reveal the presence of a lensing object more than an arcsec away from either QSO image down to a red magnitude of 23.5. An absorption feature in the spectrum of the brighter QSO image may be a signature of the lens galaxy. This line is interpreted as the Mg II λ 2799 doublet, seen at redshift z_(lens) = 1.118.

Item Type:Article
Related URLs:
URLURL TypeDescription
Djorgovski, S.0000-0002-0603-3087
Additional Information:© 1984 The American Astronomical Society. Received 1983, November 14; accepted 1984 February 22. Based in part on observations done at Lick Observatory, University of California. We are very grateful to the staff of Lick and Kitt Peak observatories for their help in our observations, and the development of equipment and data-taking software. Special thanks go to J. De Veny and W. Ditsler at Kitt Peak, and J. Miller, L. Robinson, R. Stover, T. Lauer, and R. Stone at Lick. We would also like to thank D. Weedman for stimulating correspondence, P. Monger for most valuable help in software development, M. Davis for advice in using the cross-correlation technique, and I. King and M. Davis for critical readings of the manuscript. We thank the anonymous referee for the critical comments which helped us improve the presentation of this work. This work was partly supported by NSF grant AST 81-16125 to H. S. and a University of California Graduate Fellowship to S. D.
Funding AgencyGrant Number
NSFAST 81-16125
University of California, BerkeleyUNSPECIFIED
Subject Keywords:gravitation—quasars—spectrophotometry
Record Number:CaltechAUTHORS:20190730-161718898
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97540
Deposited By: Tony Diaz
Deposited On:31 Jul 2019 15:40
Last Modified:16 Nov 2021 17:32

Repository Staff Only: item control page