Hubble Status Report - February 2003
The ACS total throughput is higher than predicted before launch and the image quality is as expected. The NICMOS cryocooler also performs as expected. The NICMOS detectors are now operated at a temperature slightly higher than the one in previous cycles making it more sensitive. The PSF, dark current and flat fields are all well behaved.
The Phase I proposal deadline, which traditionally fell in early September, has been moved for Cycle 12 to January. Since the start of the new cycle will continue to be in July, this change will shorten the time interval between the submission of observing proposals and the scheduling of the observations. In addition to the proposal categories that have existed for many cycles, STScI continues to solicit proposals in the categories of Treasury Proposals, Theory Proposals and Legacy Archive Proposals, all of which were started successfully in Cycle 11.
The ACS began to acquire images belonging to the GOODS (Great Observatories Origins Deep Survey) project. This is a large Treasury Program with a significant number of European scientists involved. As well as imaging of the two 10x16 arcmin GOODS fields through the BViz filters this program also is divided into five epochs for each field, spaced to optimise the detection of supernovae at redshifts in the range 1-1.5. The first three epochs of CDF-S (Chandra Deep Field South) have been successfully observed and several supernovae discovered. Candidate type Ia SNe can trigger a target of opportunity follow up HST program. The multi-wavelength GOODS data set (which includes a large component obtained with the ESO Telescopes), is also being used as a test for the first implementation of the Astrophysical Virtual Observatory which will be demonstrated to the AVO Science Working Group on January 20-21, 2003 at the Jodrell Bank Observatory.
An Ultra Deep Field (UDF) project has been announced by the STScI Director. The aim of the project is to image a small piece of sky as deeply as possible with the ACS in the manner of the HDF. Initial estimates expect that around 400 orbits will be used and that magnitudes about 1.5 fainter than achieved with the Hubble Deep Fields (HDF) may be attainable with the same filters. The details of field and filter choice, and the possibility of using the grism as well, are being assessed by a high-level scientific advisory committee. Observing may start in Summer 2003.
Science Highlights
European astronomers, using HST data combined with ground-based observations, found evidence for a fast moving galactic black hole, possibly being shot out during a supernova explosion (see http://sci.esa.int/hubble/news/index.cfm?aid=31&cid=630&oid=30955). ACS was used to image distant galaxies that are seen by a gigantic gravitational lens generated by the galaxy cluster Abell 1689. (See http://hubblesite.org/newscenter/archive/2003/01/)