The Supernova
Cosmology Project's
2005/6 high redshift SN search with
the Hubble Space Telescope
Decelerating and Dustfree: Targeting Supernovae in Very High
Redshift Galaxy Clusters with HST (Saul
Perlmutter, PI)
The SCP is pursuing a novel approach to obtaining Type Ia supernovae
(SNe Ia) at very high redshifts (z>~1). In a 219 orbit cycle 14
program (HST-GO 10496), we are using the Advanced Camera for Surveys
(ACS) and NICMOS on the Hubble Space Telescope (HST) to repeatedly
observe massive galaxy clusters at z>~1 to find and follow SNe.
Clusters of galaxies are known to be dominated by nearly dust-free
early type galaxies. SNe discovered in these galaxies are expected to
have negligible dust extinction, the largest source of both statistical
and systematic uncertainty in SNe derived distances. In addition,
galaxy clusters contain a population of early type galaxies at a
density approximately five times that in the high redshift field,
leading to a much higher rate of detection of SNe Ia in this
well-understood host environment. With 20 scheduled half-nights on the
Subaru telecope as well as multiple nights on the Keck and VLT
telescopes, we are obtaining spectroscopic confirmation and redshift of
newly discovered SNe and their hosts. This data will significantly
improve supernova constraints of dark energy both in terms of
statistical uncertainty, and perhaps more importantly, of systematic
uncertainty. This sample of more than 20 galaxy clusters is also being
studied for weak lensing, galaxy morphology, and color-magnitude
relationship, as part of an entire program of cluster studies.
We have published an item on CBET 546 describing the discovery of an
unidentified
transient object, found here.
An image from ACS can be found here and finding chart can be found here.
In the finding chart, the are two bright stars with fairly large
offsets from
the transient detected in the field.
The star identified with the green ruler is Vega z'=19.9.
The transient has a PA=-38.1 degrees, and an offset 40.81" west
and 52.06" north with respect to this star.
The star identified with the red ruler
is z'=19.4. The transient has a PA=-69.86 degrees, and an offset 80.94"
east and 29.68" south with respect to this star.
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