Bibcode
Scarpa, Riccardo
Bibliographical reference
HST Proposal ID #8135
Advertised on:
7
1999
Citations
0
Refereed citations
0
Description
We propose spectroscopic observations of two new gravitational lens
candidates, 0502+675 and 1440+122, discovered in our HST R-band snapshot
survey of ~100 BL Lac objects. Each contains a double point source with
separation of only 0.3 arcsec. In each case, a candidate for the lensing
galaxy is also found. For 0502+675, a subsequent NICMOS H-band image
shows that the two point sources have similar R-H colors. STIS long-slit
spectra of each point source will determine whether these candidates are
lenses and also measure the redshift of the possible lensing galaxy. Due
to the small image separation, HST spatial resolution is essential.
These two sources, if confirmed as lenses, are particularly valuable for
estimating H_0 because of the large amplitude and rapid flux variability
that characterize BL Lac objects.