Spitzer Warm Mission Workshop Introduction

The Spitzer Warm Mission Workshop was held June 4–5, 2007, to explore the science drivers for the warm Spitzer mission and help the Spitzer Science Center develop a new science operations philosophy. We must continue to maximize the science return with the reduced resources available, both using (a) the shortest two IRAC channels, and (b) archival research with the rich Spitzer archive. This paper summarizes the overview slides presented to the workshop participant

Photometric Redshifts and High-Redshift Galaxies

The Workshop "Photometric Redshifts and High‐Redshift Galaxies" was held at the Observatories of the Carnegie Institution of Washington, in Pasadena, California, on 1999 April 28–30. The 70 participants were greeted with atypically cool, overcast weather, but this did not cloud or dampen the discussions. The application of photometric redshift techniques and studies of high‐redshift galaxies are evolving so rapidly that the time seemed right to gather together the active workers in these fields and determine what is the current state of the art. Ray Weymann posed several questions that were the motivating factors in convening the workshop. Although we did not expect all of them to be answered in this forum, they provide a framework in which to examine current work and focus our future efforts

Downsizing a Great Observatory: Reinventing Spitzer in the Warm Mission

The Spitzer Space Telescope transitioned from the cryogen mission to the IRAC warm mission during 2009. This transition involved changing several areas of operations in order to cut the mission annual operating costs to 1/3 of the cryogen mission amount. In spite of this substantial cut back, Spitzer continues to have one of the highest science return per dollar ratio of any of NASA's extended missions. This paper will describe the major operational changes made for the warm mission and how they affect the science return. The paper will give several measures showing that warm Spitzer continues as one of the most scientifically productive mission in NASA's portfolio. This work was performed at the California Institute of Technology under contract to the National Aeronautics and Space Administration

Spitzer Space Telescope: Unprecedented Efficiency and Excellent Science on a Limited Budget

The Spitzer Space Telescope completed nearly six years of cryogenic operations in 2009 and in August 2011 began the third year of ‘warm’ science observations. Over 50,000 hours of science have been executed in the first 8 years of the mission. Nearly 40% of the cryogenic mission project budget was devoted to data analysis funding provided directly to the astronomical community. For the warm mission, the observatory was effectively reinvented as a new, scientifically productive mission operating at a substantially lower cost. In this paper we discuss how the design of the science operations, observing modes and observing program for the cryogenic mission led to very high observing efficiencies and maximized the observatory time devoted to science. The philosophy of maximizing science output per dollar has continued in the warm mission. The transition to warm operations has maintained an outstanding science program while reducing the project budget by nearly 70% from the cryogenic mission level

Quasar absorption line studies of galaxies and the intergalactic medium at z > 1.5

The title of this article could of course encompass an entire meeting. I will focus my comments on reviewing of what we know about the most numerous absorption lines, the neutral hydrogen absorbers, and their evolution with redshift. This field of study has undergone a renaissance in last few years driven by observations with the Hubble Space Telescope of low redshift quasar absorption lines, observations of high redshift absorbers with the HIRES instrument on Keck, and cosmological modeling that allows us to make detailed comparisons of lines of sight through simulated universes

Microlens Parallax Measurements with a Warm Spitzer

Because Spitzer is an Earth-trailing orbit, losing about 0.1 AU/yr, it is excellently located to perform microlens parallax observations toward the Magellanic Clouds (LMC/SMC) and the Galactic bulge. These yield the so-called ``projected velocity'' of the lens, which can distinguish statistically among different populations. A few such measurements toward the LMC/SMC would reveal the nature of the lenses being detected in this direction (dark halo objects, or ordinary LMC/SMC stars). Cool Spitzer has already made one such measurement of a (rare) bright red-clump source, but warm (presumably less oversubscribed) Spitzer could devote the extra time required to obtain microlens parallaxes for the more common, but fainter, turnoff sources. Warm Spitzer could observe bulge microlenses for 38 days per year, which would permit up to 24 microlens parallaxes per year. This would yield interesting information on the disk mass function, particularly old brown dwarfs, which at present are inaccessible by other techniques. Target-of-Opportunity (TOO) observations should be divided into RTOO/DTOO, i.e., ``regular'' and ``disruptive'' TOOs, as pioneered by the Space Interferometry Mission (SIM). LMC/SMC parallax measurements would be DTOO, but bulge measurements would be RTOO, i.e., they could be scheduled in advance, without knowing exactly which star was to be observed.Comment: 6 pages + 1 Figure, To be presented at The Warm Spitzer Mission Workshop, 4-5 June 2007, Pasaden

Astronomical Data Reduction and Analysis for the Next Decade

The astronomical community has become very sophisticated in setting requirements and figures of merit for the technical capabilities of new observatories. Sensitivity, field of view, spatial and energy resolution, observing efficiency and the lifetime of the facility are all set out to address scientific problems as efficiently as possible. The ultimate goal of these facilities, however, is not simply to gather data, but to create knowledge. It is thus important to consider the process of converting data to knowledge and ask whether there are ways to improve this for the coming generation. Software for data reduction and analysis provides a key link in this chain. Modest investments in this area can have a very large impact on astronomy as a whole, if they are made wisely. Conversely, it is possible to waste significant amounts of money on software efforts that never fulfill their promise. We need to learn from the successes and failures of the past to try to maximize our productivity in astronomy as a whole. That means working more closely together across agencies, projects, institutions and disciplines to share in building and maintaining this essential infrastructure

Cosmological Evolution of the Universe Neutral Gas Mass Measured by Quasar Absorption Systems

The cosmological evolution of neutral hydrogen is an efficient way of tracing structure formation with redshift. It indicates the rate of evolution of gas into stars and hence the gas consumption and rate star formation history of the Universe. In measuring HI, quasar absorbers have proven to be an ideal tool and we use observations from a recent survey for high-redshift quasar absorption systems together with data gathered from the literature to measure the cosmological comoving mass density of neutral gas. This paper assumes Omega_M=0.3, Omega_lambda=0.7 and h=0.65.Comment: 3 pages, 2 figures. To appear in the proceedings of the "Cosmic Evolution" conference, held at l'Institut d'Astrophysique de Paris, November 13-17, 200

High Redshift Candidates and the Nature of Small Galaxies in the Hubble Deep Field

We present results on two related topics: 1. A discussion of high redshift candidates (z>4.5), and 2. A study of very small galaxies at intermediate redshifts, both sets being detected in the region of the northern Hubble Deep Field covered by deep NICMOS observations at 1.6 and 1.1 microns. The high redshift candidates are just those with redshift z>4.5 as given in the recent catalog of Thompson, Weymann and Storrie-Lombardi, while the ``small galaxy'' sample is defined to be those objects with isophotal area <= 0.2 squ. arcsec and with photometric redshifts 1<z<4.5. Of the 19 possible high redshift candidates listed in the Thompson et al. catalog, 11 have (nominal) photometric redshifts less than 5.0. Of these, however, only 4 are ``robust'' in the sense of yielding high redshifts when the fluxes are randomly perturbed with errors comparable to the estimated measuring error in each wave band. For the 8 other objects with nominal photometric redshifts greater than 5.0, one (WFPC2 4--473) has a published spectroscopic redshift. Of the remaining 7, 4 are robust in the sense indicated above. Two of these form a close pair (NIC 586 and NIC 107). The redshift of the object having formally the highest redshift, at 6.56 (NIC118 = WFPC2 4--601), is problematic, since F606W and F814W flux are clearly present, and the nature of this object poses a dilemma. (abridged)Comment: 44 pages, 12 figures, to appear in ApJ v591, July 10, 200