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This paper presents the Hubble Ultra Deep Field (HUDF), a one million second exposure of an 11 square minute-of-arc region in the southern sky with the Advanced Camera for Surveys on the Hubble Space Telescope using Director's Discretionary Time. The exposure time was divided among four filters, F435W (B 435), F606W (V 606), F775W (i 775), and F850LP (z(More)
The ADS abstract service at: http://adswww.harvard.edu has been updated considerably in the last year. New capabilities in the search engine include searching for multi-word phrases and searching for various logical combinations of search terms. Through optimization of the custom built search software, the search times were decreased by a factor of 4 in the(More)
We present the new PyRAF-based 'MultiDrizzle' script, which is aimed at providing a one-step approach to combining dithered HST images. The purpose of this script is to allow easy interaction with the complex suite of tasks in the IRAF/STSDAS 'dither' package, as well as the new 'PyDrizzle' task, while at the same time retaining the flexibility of these(More)
We have developed a method for the linear reconstruction of an image from undersampled, dithered data, which has been used to create the distributed, combined Hubble Deep Field 1 images – the deepest optical images yet taken of the universe. The algorithm, known as Variable-Pixel Linear Reconstruction (or informally as " drizzling "), preserves photometry(More)
We introduce SLIM, a slitless spectroscopy simulator written in Python which can be used to simulate the ACS grism and prism modes. SLIM was designed to produce realistic, pho-tometrically correct two-dimensional images from which spectra can be extracted. Here, we outline the features of SLIM and present some WFC and HRC grism simulations of emission line(More)
We present a set of tasks developed to process dithered undersampled images. These procedures allow one to easily determine the offsets between images and then combine the images using Variable-Pixel Linear Reconstruction, otherwise know as " drizzle ". This algorithm, originally developed for the combination of the images in the Hubble Deep Field(Williams(More)
Point spread function (PSF) models are critical to Hubble Space Telescope (HST) data analysis. Astronomers unfamiliar with optical simulation techniques need access to PSF models that properly match the conditions of their observations, so any HST modeling software needs to be both easy-to-use and have detailed information on the telescope and instruments.(More)
The Hubble Legacy Archive (HLA) aims to create calibrated science data from the Hubble Space Telescope archive and make them accessible via user-friendly and Virtual Observatory (VO) compatible interfaces. It is a collaboration between the Space Telescope Science Institute (STScI), the Canadian Astronomy Data Centre (CADC) and the Space Telescope-European(More)