Transection of the Thoracic Aorta

Moffat, Robert C.; Krome, Ronald L.; Berkas, Ernest M.

doi:10.1177/153857446900300305

Cited by 18 publications

(19 citation statements)

References 5 publications

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“…A 2-pixel (0.2 arcsec) aperture was used to build the upper CMD. As for the PSF fitting, we found the best-fitting Moffat function with b ¼ 1:5 (Moffat 1969;Elson et al 1995) to our template and applied it to all detected objects, resulting in the lower CMD in the figure. The aperture photometry data yielded narrower main-sequence and giant branches as attested by Fig.…”

Section: Sample Selection and Photometrymentioning

confidence: 99%

Deep colour-magnitude diagrams of LMC field stars imaged withHST

Castro

Santiago

Gilmore

et al. 2001

Monthly Notices of the Royal Astronomical Society

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We present deep photometry (V≲26) in V and I bands obtained with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope for 7 fields ∼5° away from the Large Magellanic Cloud centre. The fields contain, typically, 2000 stars each. Isochrones were fitted to the colour–magnitude diagrams in order to identify different star populations in these fields. An old population (τ>10 Gyr) has been found in all fields. Some events of enhanced star formation, with ages between 2 and 4 Gyr, were identified in the fields localized in the north to north‐west regions. Luminosity functions of low‐mass stars were also obtained for all fields. Kolmogorov Smirnov test results suggest differences smaller than 30 per cent in the mixture of stellar populations contributing to the fields. Finally, density profiles were derived for old and intermediate‐age stars. The former shows a slightly steeper decline than the latter.

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Section: Sample Selection and Photometrymentioning

confidence: 99%

Deep colour-magnitude diagrams of LMC field stars imaged withHST

Castro

Santiago

Gilmore

et al. 2001

Monthly Notices of the Royal Astronomical Society

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“…To better model the PSF, we fit a Moffat profile (Moffat 1969) to the few unsaturated stars in each chip and in each filter of the following form:…”

Section: Compact Source Selectionmentioning

confidence: 99%

Quasar Candidates in the Hubble Deep Field

Conti

Kennefick

Martini

et al. 1999

The Astronomical Journal

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We focus on the search for unresolved faint quasars and AGN in the crude combine images using a multicolor imaging analysis that has proven very successful in recent years. Quasar selection was carried out both in multicolor space and in "profile space," defined as the multi-parameter space formed by the radial profiles of the objects in the different images. By combining the dither frames available for each filter, we were able to obtain well-sampled radial profiles of the objects and measure their deviation from that of a stellar source. We also generated synthetic quasar spectra in the range 1.0 < z < 5.5 and computed expected quasar colors. We determined that the data are 90% complete for point sources at 26.2, 28.0, 27.8, 26.8 in the F300W, F450W, F606W and F814W filters, respectively. We find 41 compact objects in the HDF: 8 pointlike objects with colors consistent with quasars or stars, 18 stars, and 15 slightly resolved objects, 12 of which have colors consistent with quasars or stars. We estimate the upper limit of unresolved and slightly resolved quasars/AGNs with V < 27.0 and z < 3.5 to be 20 objects (16,200 per deg^2). We find good agreement among authors on the number of stars and the lack of quasar candidates with z > 3.5. We find more quasar candidates than previous work because of our more extensive modeling and use of all of the available color information. (abridged)Comment: We have clarified our discussion and conclusions, added some references and removed the appendix, which is now available from the first author. 37 pages including 10 embedded postscript figures and 6 tables. To appear in the Feb. 99 issue of A

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“…For each galaxy, four synthetic low-resolution images were generated. This involved the convolution of each original or stacked image with Moffat (1969) functions of ( √ 16 − d 2 ) ′′ , 8 ′′ , 16 ′′ and 32 ′′ FWHM in the case of the classical galaxies or with the same functions of 1 ′ , 2 ′ , 4 ′ and 8 ′ FWHM, in the case of NGC 147; where d was the FWHM of seeing disc at the time of the original observation(s). In order to minimize edge effects, each digital image was embedded in a very much larger array of pixels (in which each pixel in the surrounding grid was set to zero) before any convolution was performed.…”

Section: System Stabilitymentioning

confidence: 99%

“…This effect is analogous to the effect of ordinary seeing conditions on more distant galaxies of the same type and physical size. The image resolution function adopted was that of Moffat (1969) and the FWHM of the synthetic seeing discs are shown in arcsec. The curves represent model Sérsic profiles fitted to all plotted isophotes.…”

Section: High-resolution Imagesmentioning

confidence: 99%

“…In order to test the applicability of the t system to images due to point sources, we simulated the surface photometry one might expect to obtain for two model point spread functions. The two model profiles adopted were based on Moffat functions using the original parameter values quoted by Moffat (1969) for traced stellar images on Hamburg Schmidt and the Lick 120-inch reflector photographic plates. The adopted parameter values were β = 4 and R = 5 × 10 −5 m for the Hamburg plates and β = 2.72, and R = 1.12 × 10 −4 m for the Lick plates.…”

Section: Low-resolution Imagesmentioning

confidence: 99%

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The $\vec{t}$ system; a new system for estimating the total magnitudes of galaxies

Young¹,

Metcalfe²,

Zhu³

et al. 1998

Astron. Astrophys. Suppl. Ser.

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We present a new, but simple, procedure for estimating the total magnitudes of galaxies. This procedure involves the out-focusing of digital galaxy images numerically, the fitting of the resulting surface-brightness profiles with a single generalised profile model and the extrapolation of the fitted profiles to infinite radial distances. This new system, which we denote t, differs fundamentally from the T system (of the Reference Catalog of Bright Galaxies series) in that: (1) it enables a galaxy's luminosity profile to be extrapolated without the need for any prior morphological classification, and (2) it is applicable to images of widely different spatial resolutions (including unresolved ones) because it takes into account systematic effects due to differential image resolution. It also differs fundamentally from the Kron system in that: (1) it can be derived directly from surface photometry without the need to go back to the plate scans or CCD frames (unless the surface photometry is of high resolution and/or the galaxies being measured are very bright), and (2) it can cope with merged images (provided they are separable by image-segmentation software). Through worked examples, we demonstrate the stability of t-system total magnitudes with respect to morphological type, the seeing conditions at the time of observation, degree of smoothing and limiting isophote. We also compare and contrast the new system with both the T system and the Kron system, and investigate the advantages and limitations of each of the three systems.

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Transection of the Thoracic Aorta

Cited by 18 publications

References 5 publications

Deep colour-magnitude diagrams of LMC field stars imaged withHST

Deep colour-magnitude diagrams of LMC field stars imaged withHST

Quasar Candidates in the Hubble Deep Field

The $\vec{t}$ system; a new system for estimating the total magnitudes of galaxies

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