Fundamental Plane Distances to Early-type Field Galaxies in the South Equatorial Strip. I. The Spectroscopic Data

Radial velocities and central velocity dispersions are derived for 238 E/S0 galaxies from medium-resolution spectroscopy. New spectroscopic data have been obtained as part of a study of the Fundamental Plane distances and peculiar motions of early-type galaxies in three selected directions of the South Equatorial Strip, undertaken in order to investigate the reality of large-scale streaming motion; results of this study have been reported in M\"uller $et$ $al.$ (1998). The new APM South Equatorial Strip Catalog ($-17^{\circ}.5 < \delta < +2^{\circ}.5$) was used to select the sample of field galaxies in three directions: (1) 15h10 - 16h10; (2) 20h30 - 21h50; (3) 00h10 - 01h30. The spectra obtained have a median S/N per ${\AA}$ of 23, an instrumental resolution (FWHM) of $\sim$ 4 ${\AA}$, and the spectrograph resolution (dispersion) is $\sim$ 100 km~s$^{-1}$. The Fourier cross-correlation method was used to derive the radial velocities and velocity dispersions. The velocity dispersions have been corrected for the size of the aperture and for the galaxy effective radius. Comparisons of the derived radial velocities with data from the literature show that our values are accurate to 40 km~s$^{-1}$. A comparison with results from J\orgensen et al. (1995) shows that the derived central velocity dispersion have an rms scatter of 0.036 in $\log \sigma$. There is no offset relative to the velocity dispersions of Davies et al. (1987).Comment: accepted for publication in Astronomy & Astrophysics Supplement Serie

Flows on scales of 150 Mpc?

We investigate the reality of large-scale streaming on scales of up to 150 Mpc using the peculiar motions of galaxies in three directions. New R-band CCD photometry and spectroscopy for elliptical galaxies is used. The Fundamental Plane distance indicator is calibrated using the Coma cluster and an inhomogeneous Malmquist bias correction is applied. A linear bulk-flow model is fitted to the peculiar velocities in the sample regions and the results do not reflect the bulk flow observed by Lauer and Postman (LP). Accounting for the difference in geometry between the galaxy distribution in the three regions and the LP clustersconfirms the disagreement; assuming a low-density CDM power spectrum, we find that the observed bulk flow of the galaxies in our sample excludes the LP bulk flow at the 99.8% confidence level.Comment: 16 pages, 1 figur

The extinction by dust in the outer parts of spiral galaxies

To investigate the distribution of dust in Sb and Sc galaxies we have analyzed near-infrared and optical surface photometry for an unbiased sample of 37 galaxies. Since light in the $K$-band is very little affected by extinction by dust, the $B-K$ colour is a good indicator of the amount of extinction, and using the colour-inclination relation we can statistically determine the extinction for an average Sb/Sc galaxy. We find in general a considerable amount of extinction in spiral galaxies in the central regions, all the way out to their effective radii. In the outer parts, at D$_{K,21}$, or at 3 times the typical exponential scale lengths of the stellar distribution , we find a maximum optical depth of 0.5 in $B$ for a face-on galaxy. If we impose the condition that the dust is distributed in the same way as the stars, this upper limit would go down to 0.1.Comment: 4 pages, postscript, gzip-compressed, uuencoded, includes 2 figures. Accepted for publication in Astronomy & Astrophysics, Letter

Fundamental Plane Distances to Early-type Field Galaxies in the South Equatorial Strip. I. The Spectroscopic Data

Radial velocities and central velocity dispersions are derived for 238 E/S0 galaxies from medium-resolution spectroscopy. New spectroscopic data have been obtained as part of a study of the Fundamental Plane distances and peculiar motions of early-type galaxies in three selected directions of the South Equatorial Strip, undertaken in order to investigate the reality of large-scale streaming motion; results of this study have been reported in M\ uller $et$ $al.$ (1998). The new APM South Equatorial Strip Catalog (−17.5 \u3c δ \u3c +2.5) was used to select the sample of field galaxies in three directions: (1) 15h10 – 16h10; (2) 20h30 – 21h50; (3) 00h10 – 01h30. The spectra obtained have a median S/N per ̊A of 23, an in- strumental resolution (FWHM) of ∼ 4 ̊A, and the spectro- graph resolution (dispersion) is ∼ 100 km s−1. The Fourier cross-correlation method was used to derive the radial ve- locities and velocity dispersions. The velocity dispersions have been corrected for the size of the aperture and for the galaxy effective radius. Comparisons of the derived radial velocities with data from the literature show that our values are accurate to 40 km s−1. A comparison with results from Jørgensen et al. (1995) shows that the derived central velocity dispersion have an rms scatter of 0.036 in log σ. There is no offset relative to the velocity dispersions of Davies et al. (1987)

The Hubble Legacy Archive NICMOS Grism Data

The Hubble Legacy Archive (HLA) aims to create calibrated science data from the Hubble Space Telescope archive and make them accessible via user-friendly and Virtual Observatory (VO) compatible interfaces. It is a collaboration between the Space Telescope Science Institute (STScI), the Canadian Astronomy Data Centre (CADC) and the Space Telescope - European Coordinating Facility (ST-ECF). Data produced by the Hubble Space Telescope (HST) instruments with slitless spectroscopy modes are among the most difficult to extract and exploit. As part of the HLA project, the ST-ECF aims to provide calibrated spectra for objects observed with these HST slitless modes. In this paper, we present the HLA NICMOS G141 grism spectra. We describe in detail the calibration, data reduction and spectrum extraction methods used to produce the extracted spectra. The quality of the extracted spectra and associated direct images is demonstrated through comparison with near-IR imaging catalogues and existing near-IR spectroscopy. The output data products and their associated metadata are publicly available through a web form at http://hla.stecf.org and via VO interfaces. In total, 2470 spectra of 1923 unique targets are included in the current release.Comment: 18 pages, 21 figures, accepted for publication in Astronomy & Astrophysic