FOCAS - Faint Object Classification and Analysis System

Jarvis, J. F.; Tyson, J. A.

doi:10.1086/112907

Cited by 218 publications

(145 citation statements)

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“…Object detection, photometry and morphological classification was carried out with FOCAS (Valdes 1994;Jarvis & Tyson 1981). The reliability of the detection process was extensively tested on simulated images generated with the iraf-package noao.artdata.…”

Section: Object Detection and Photometrymentioning

confidence: 99%

A wide field survey at the Northern Ecliptic Pole

Kümmel

Wagner²

2001

A&A

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Abstract. We present a medium deep survey carried out in the three filters Bj, R and K. The survey covers homogeneously the central square degree around the Northern Ecliptic Pole (NEP) down to a completeness limit (95%) of 24.25, 23.0 and 17.5 mag in Bj, R and K, respectively. While the near infrared data have been presented in the first paper of this series, here we concentrate on the optical data and the results based on the combined BjRK-data. The unique combination of area and depth in our survey allows to perform a variety of investigations based on homogeneous material covering more than ten magnitudes in apparent brightness. We analyze the number counts for point-like and extended sources in Bj and R to determine the slopes in d log N/dm and to test for possible breaks therein. While we can confirm the slopes found in previous works with a higher statistical significance, the largest uncertainty remaining for the amplitudes is galactic extinction. We determine the colour distributions of galaxies in Bj − R and R − K down to Bj = 24.0 and K = 18.0 mag, respectively. The distributions in both colours are modeled using galaxy spectral evolution synthesis. We demonstrate that the standard models of galaxy evolution are unable to reproduce the steady reddening trend in R − K despite flawless fits to the colour distributions in the optical (Bj −R). The BjRK data collected over a large area provides the opportunity to select rare objects like candidates for high-redshift galaxies and extremely red objects (EROs, R − K > 5.0) and to determine their surface density. Our EROs are selected at an intermediate magnitude range and contain contribution from both galactic as well as extragalactic sources. At K < 16.5 mag, where a morphological classification is possible, the stellar component dominates the sample.

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Section: Object Detection and Photometrymentioning

confidence: 99%

A wide field survey at the Northern Ecliptic Pole

Kümmel

Wagner²

2001

A&A

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“…This is basic science as usual. Such computational processing has its levels of accuracy and precision; and its reliability is de facto determined by values such as ease of implementation, cost, and running time, as well as the available hardware (Jarvis & Tyson 1981). Usually, nothing significant hinges on such routine identification of astronomical objects.…”

Section: Scientific Theories -Acceptance Versus Beliefmentioning

confidence: 99%

Science, values, and pragmatic encroachment on knowledge

Miller

2014

Euro Jnl Phil Sci

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Philosophers have recently argued, against a prevailing orthodoxy, that standards of knowledge partly depend on a subject's interests; the more is at stake for the subject, the less she is in a position to know. This view, which is dubbed "Pragmatic Encroachment" has historical and conceptual connections to arguments in philosophy of science against the received model of science as value free. I bring the two debates together. I argue that Pragmatic Encroachment and the model of value-laden science reinforce each other. Drawing on Douglas' argument about the indispensability of value judgments in science, and psychological evidence about people's inability to objectively reason about what they care about, I introduce a novel argument for Pragmatic Encroachment.

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“…Object detection was carried out using FOCAS (Jarvis and Tyson 1981) with a detection threshold of 2.5σ of the sky fluctuations per pixel. A minimum of ∼ (F W HM) 2 connecting pixels above the threshold was required for detection.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Clustering of Red Galaxies Near a Radio-Loud Quasar at z = 1.086

Tanaka

Yamada

Aragón-Salamanca

et al. 1999

Galaxy Interactions at Low and High Redshift

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1 Partly based on observations made with the University of Hawaii 2.2 m telescope, and the Isaac Newton Telescope, operated on the island of La Palma by the Royal Greenwich Observatory in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.-2 - ABSTRACTWe have obtained new deep optical and near-infrared images of the field of the radio-loud quasar 1335.8+2834 at z = 1.086 where an excess in the surface number density of galaxies was reported by Hutchings et al. [AJ, 106, 1324] from optical data. We found a significant clustering of objects with very red optical-near infrared colors, 4 ∼ < R − K ∼ < 6 and 3 ∼ < I − K ∼ < 5 near the quasar.The colors and magnitudes of the reddest objects are consistent with those of old (12 Gyr old at z = 0) passively-evolving elliptical galaxies seen at z = 1.1, clearly defining a 'red envelope' like that found in galaxy clusters at similar or lower redshifts. This evidence strongly suggests that the quasar resides in a moderately-rich cluster of galaxies (richness-class ≥ 0). There is also a relatively large fraction of objects with moderately red colors (3.5 < R − K < 4.5) which have a distribution on the sky similar to that of the reddest objects. They may be interpreted as cluster galaxies with some recent or on-going star formation.

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FOCAS - Faint Object Classification and Analysis System

Cited by 218 publications

References 0 publications

A wide field survey at the Northern Ecliptic Pole

A wide field survey at the Northern Ecliptic Pole

Science, values, and pragmatic encroachment on knowledge

Clustering of Red Galaxies Near a Radio-Loud Quasar at z = 1.086

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