Brett S. Blacker

The Hubble Deep Field: Observations, data reduction, and galaxy photometry

The Hubble Deep Field (HDF) is a Director’s Discretionary program on HST in Cycle 5 to image an undistinguished field at high Galactic latitude in four passbands as deeply as reasonably possible. These images provide the most detailed view to date of distant field galaxies and are likely to be important for a wide range of studies in galaxy evolution and cosmology. In order to optimize observing in the time available, a field in the northern continuous viewing zone was selected and images were taken for ten consecutive days, or approximately 150 orbits. Shorter 1-2 orbit images were obtained of the fields immediately adjacent to the primary HDF in order to facilitate spectroscopic follow-up by ground-based telescopes. The observations were made from 18 to 30 December 1995, and both raw and reduced data have been put in the public domain as a community service. We present a summary of the criteria for selecting the field, the rationale behind the filter selection and observing times in each band, and the strategies for planning the observations to maximize the exposure time while avoiding earth-scattered light. Data reduction procedures are outlined, and images of the combined frames in each band are presented. Objects detected in these images are listed in a catalog with their basic photometric parameters.

The Hubble Deep Field South: Formulation of the Observing Campaign

Deep, multiband observations of high Galactic latitude fields are an essential tool for studying topics ranging from Galactic structure to extragalactic background radiation. The Hubble Deep Field (HDF-N) observations obtained in 1995 December established a standard for such narrow, deep surveys. The field has been extensively analyzed by a variety of groups and has been widely studied with imaging and spectroscopy over wavelengths ranging from 10-3 to 2 × 105 μm. We describe here a second deep field campaign (HDF-S), this time in the southern hemisphere, undertaken by the Hubble Space Telescope (HST) in 1998 October in a program very similar to the northern Hubble Deep Field. Imaging and spectroscopy of three adjacent fields in the southern continuous viewing zone were obtained simultaneously for 150 orbits, and a mosaic of flanking fields was imaged for 27 additional orbits. Two important features of the HDF-S distinguish it from the HDF-N: the campaign included parallel observations by the three main HST instruments—WFPC2, STIS, and NICMOS—and the HDF-S location was selected to place a bright z = 2.24 quasar in the STIS field of view. The HDF-S observations consist of WFPC2 images in filters close to U, B, V, and I, a deep STIS image of the field surrounding the quasar, spectroscopy of the quasar with STIS from 1150 to 3560 A, and deep imaging of an adjacent field with NICMOS camera 3 at 1.1, 1.6, and 2.2 μm. All of the HDF-S data were fully reduced and made publicly available within 2 months of the observations, and we describe here the selection of the fields and the observing strategy that was employed. Detailed descriptions of the data and the reduction techniques for each field, together with the corresponding source catalogs, appear in separate papers.

The scientific output of the Hubble Space Telescope from objective metrics

After a decade of Hubble Space Telescope (HST) operations, observations, and publications, the Space Telescope Science Institute (STScI) decided it was pertinent to measure the scientific effectiveness of the HST observing programs. To this end, we have developed a methodology and a set of software tools to measure - quantitatively and objectively - the impact of HST observations on astrophysical research. We have gathered Phase I and Phase II information on the observing programs from existing STScI databases, among them the Multi-mission Archive at Space Telescope (MAST). We have gathered numbers of refereed papers and their citations from the Institute for Scientific Information (ISI) and the NASA Astrophysics Data System (ADS), cross-checking information and verifying that our information is as complete and reliable as possible. We have created a unified database with links connecting any specific set of HST observations to one or more scientific publications. We use this system to evaluate the scientific outcomes of HST observations according to type and time. In this paper, we present a few such HST metrics that we are using to evaluate the scientific effectiveness of the Hubble Space Telescope.

APT: the phase I tool for HST cycle 12

In the continuing effort to streamline our systems and improve service to the science community, the Space Telescope Science Institute (STScI) is developing and releasing, APT - The Astronomer’s Proposal Tool as the new interface for Hubble Space Telescope (HST) Phase I and Phase II proposal submissions for HST Cycle 12. APT, was formerly called the Scientists Expert Assistant (SEA), which started as a prototype effort to try and bring state of the art technology, more visual tools and power into the hands of proposers so that they can optimize the scientific return of their programs as well as HST. Proposing for HST and other missions, consists of requesting observing time and/or archival research funding. This step is called Phase I, where the scientific merit of a proposal is considered by a community based peer-review process. Accepted proposals then proceed thru Phase II, where the observations are specified in sufficient detail to enable scheduling on the telescope. In this paper, we will present our concept and implementation plans for our Phase I development and submission tool, APT. More importantly, we will go behind the scenes and discuss why its important for the Science Policies Division (SPD) and other groups at the STScI to have a new submission tool and submission output products. This paper is an update of the status of the HST Phase I Proposal Processing System that was described in the published paper “A New Era for HST Phase I Development and Submission.”

How operational issues impact science peer review

In some eyes, the Phase I proposal selection process is the most important activity handled by the Space Telescope Science Institute (STScI). Proposing for HST and other missions consists of requesting observing time and/or archival research funding. This step is called Phase I, where the scientific merit of a proposal is considered by a community based peer-review process. Accepted proposals then proceed thru Phase II, where the observations are specified in sufficient detail to enable scheduling on the telescope. Each cycle the Hubble Space Telescope (HST) Telescope Allocation Committee (TAC) reviews proposals and awards observing time that is valued at

APT: what it has enabled us to do

0.5B, when the total expenditures for HST over its lifetime are figured on an annual basis. This is in fact a very important endeavor that we continue to fine-tune and tweak. This process is open to the science community and we constantly receive comments and praise for this process. In this last year we have had to deal with the loss of the Space Telescope Imaging Spectrograph (STIS) and move from 3-gyro operations to 2-gyro operations. This paper will outline how operational issues impact the HST science peer review process. We will discuss the process that was used to recover from the loss of the STIS instrument and how we dealt with the loss of 1/3 of the current science observations. We will also discuss the issues relating to 3-gyro vs. 2-gyro operations and how that changes impacted Proposers, our in-house processing and the TAC.

The Hubble Deep Field Observations

With the development and operations deployment of the Astronomers Proposal Tool (APT), Hubble Space Telescope (HST) proposers have been provided with an integrated toolset for Phase I and Phase II. This toolset consists of editors for filling out proposal information, an Orbit Planner for determining observation feasibility, a Visit Planner for determining schedulability, diagnostic and reporting tools and an integrated Visual Target Tuner (VTT) for viewing exposure specifications. The VTT can also overlay HST’s field of view on user-selected Flexible Image Transport System (FITS) images, perform bright object checks and query the HST archive. In addition to these direct benefits for the HST user, STScI’s internal Phase I process has been able to take advantage of the APT products. APT has enabled a substantial streamlining of the process and software processing tools, which enabled a compression by three months of the Phase I to Phase II schedule, allowing to schedule observations earlier and thus further benefiting HST observers. Some of the improvements to our process include: creating a compact disk (CD) of Phase I products; being able to print all proposals on the day of the deadline; link the proposal in Portable Document Format (PDF) with a database, and being able to run all Phase I software on a single platform. In this paper we will discuss the operational results of using APT for HSTs Cycles 12 and 13 Phase I process and will show the improvements for the users and the overall process that is allowing STScI to obtain scientific results with HST three months earlier than in previous years. We will also show how APT can be and is being used for multiple missions.