Reply to S.C. Lin's rebuttal

Chapman, D.; Gault, D. E.

doi:10.1029/jz072i014p03736

Cited by 3 publications

(4 citation statements)

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“…We note that there has been some controversy over artifacts at the core of AGN galaxies imaged with AO, which imitate expected AGN structures (spiral arms, tori, bars, etc.). Firstly, all structures treated as physical in this paper are either further from the nucleus, or else they are distinctly different and more extended than the artifacts cataloged in Chapman et al (1998Chapman et al ( , 1999a. Secondly, we have compared the general morphology with HST-NICMOS images (Alonso-Herrero, private communication), which shows similar features, although at a lower spatial resolution at Kband and with 0.1 ′′ pixels compared with our 0.034 ′′ pixels.…”

Section: Core Structuresmentioning

confidence: 92%

“…However, in the central 0.5 arcsec of the galaxy, subtracting isophotal fitting models (unsharp masking) reveals prominent artifacts which obscure structural details. as described in Chapman et al (1999aChapman et al ( , 1998.…”

Section: Core Structuresmentioning

confidence: 99%

“…The images are distorted by PSF artifacts in the central 0.5 ′′ , plus the above mentioned CCD bleeding in the HST image. However, the extent and position angle (PA) of 43 • indicate that this feature is likely unrelated to the AOB artifacts described in Chapman et al (1999aChapman et al ( ,1998. Although the HST CCD bleeding lies along a similar PA, the feature appears in all the near-IR colour maps by themselves.…”

Section: Core Structuresmentioning

confidence: 99%

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Near-infrared adaptive optics imaging of nuclear spiral structure in the Seyfert galaxy NGC 3227

Chapman

Morris

Walker

2002

Monthly Notices of the Royal Astronomical Society

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We present high spatial resolution, near‐infrared images in J, H and K of the nucleus of NGC 3227, obtained with the Adaptive Optics Bonnette on the Canada–France–Hawaii Telescope. The ∼0.15 arcsec (17 pc) resolution allows structures to be probed in the core region. Dust obscuration becomes significantly less pronounced at longer wavelengths, revealing the true geometry of the core region. We are able to identify two main features in our maps: (i) a spiralling association of knots with a counterpart in a Hubble Space Telescope F606W image; and (ii) a smaller‐scale annulus, orthogonal to the spiral of knots. These features may provide a means to transport material inwards to fuel the active nucleus.

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Section: Core Structuresmentioning

confidence: 92%

Section: Core Structuresmentioning

confidence: 99%

Section: Core Structuresmentioning

confidence: 99%

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Near-infrared adaptive optics imaging of nuclear spiral structure in the Seyfert galaxy NGC 3227

Chapman

Morris

Walker

2002

Monthly Notices of the Royal Astronomical Society

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“…This illustrates that the practice of picking out low S/N ratio sources ‘by eye’ in SCUBA surveys is not very effective. Our group has also conducted two observing programmes designed to understand the submillimetre properties of Lyman‐break galaxies (LBGs, Chapman et al 2000) and optically faint radio sources (OFRS, Chapman et al 2002). These types of source will be discussed further in Paper II.…”

Section: Submillimetre Sources In the Hdfmentioning

confidence: 99%

The Hubble Deep Field North SCUBA Super-map - I. Submillimetre maps, sources and number counts

Borys

Chapman

Halpern

et al. 2003

Monthly Notices RAS

227

349

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We investigate the emission of submillimetre‐wave radiation from galaxies in a 165 arcmin2 region surrounding the Hubble Deep Field North. The data were obtained from dedicated observing runs from our group and others using the SCUBA camera on the James Clerk Maxwell Telescope (JCMT), and combined using techniques specifically developed for low signal‐to‐noise ratio source recovery. The resulting ‘Super‐map’ is derived from approximately 60 shifts of JCMT time, taken in a variety of observing modes and chopping strategies, and combined here for the first time. At 850 μm we detect 19 sources at >4σ, including five not previously reported. We also list an additional 15 sources between 3.5 and 4.0σ (where two are expected by chance). The 450‐μm map contains five sources at >4σ. We present a new estimate of the 850‐ and 450‐μm source counts. The number of submillimetre galaxies we detect account for approximately 40 per cent of the 850‐μm submillimetre background, and we show that mild extrapolations can reproduce it entirely. A clustering analysis fails to detect any significant signal in this sample of SCUBA‐detected objects. A companion paper describes the multiwavelength properties of the sources.

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Dean Chapman's Contributions to Tektite Science

Norwick

2012

Earth Sciences History

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Dean Roden Chapman (1922-1995), an engineer and scientist at NASA Ames Research Center, was one of the founders of astronautics (rocket science). He used his laboratory to produce objects that are very similar to Australian tektites. There were two major questions about tektites in his day: did they come for the Earth or the Moon? And were they caused by meteor impacts or volcanic eruptions? Chapman came to believe that tektites were caused by meteor impacts on the Moon. He made many contributions to our understanding of tektites and was also one of the people who helped NASA get to the Moon. One percent of the Moon was covered with little glass spheres, but they are quite different from the tektites known on the Earth. The data from the Moon rocks was largely incompatible with the theory that terrestrial tektites are derived from the Moon. Chapman stopped publishing papers about tektites, but he remained interested in the subject for the rest of his life and believed that in the long run the lunar impact theory might become dominant again as new data was returned from the Moon. From our present understanding of tektites and the Moon, Chapman failed because he privileged the facts that he generated himself in his laboratory. He was not prepared to study the messy complexity of natural products. He was misled by the meteorite science traditions used in tektite science. He did not use appropriate statistical procedures, and because he was such a famous scientist in his own field the editors of two major journals in which he published did not properly assist him when he was working outside his area of major competence.

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Reply to S.C. Lin's rebuttal

Cited by 3 publications

References 0 publications

Near-infrared adaptive optics imaging of nuclear spiral structure in the Seyfert galaxy NGC 3227

Near-infrared adaptive optics imaging of nuclear spiral structure in the Seyfert galaxy NGC 3227

The Hubble Deep Field North SCUBA Super-map - I. Submillimetre maps, sources and number counts

Dean Chapman's Contributions to Tektite Science

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