J/AJ/105/393 Small Drift Scan Survey Galaxies Northern Sky (Kent+ 1993)
A Small Drift Scan Survey for Galaxies in the Northern Sky
Kent S.M., Ramella M., Nonino M.
<Astron. J. 105, 393 (1993)>
=1993AJ....105..393K 1993AJ....105..393K
ADC_Keywords: Galaxy catalogs ; Magnitudes ; Selected areas
Abstract:
The file is an ASCII text file containing data for 1053 galaxies
brighter than 18.0 mag. in the filter used. The effective wavelength
of this filter for objects that have the color of galaxies closely
matches that of Thuan and Gunn r filter. The strip covered in the
survey is 12 arcmin wide by 60 degree long. The observations were
carried out on the night of 23 May 1990, using the drift scanning
technique, with the 24 inch telescope of the Whipple Observatory.
The effective integration time was 57 s.
Introduction:
One key problem of galaxy surveys using photographic plates is an
accurate magnitude calibration. Moreover sensitivity and vignetting
variations across the plate, need to be removed. The drift-scan
technique is a viable alternative: in this observing mode the
telescope tracking is stopped and the CCD is clocked at the sidereal
rate. CCD columns are aligned in the east-west direction. The CCD is
read continuously, building up an image of a strip of the sky.
Data were reduced in the standard manner, but replacing bias with
drift dark (CCD is operating in drift scan mode with the shutter
closed). Flatfields were obtained from median averaging sets of data
frames. Astrometry was done using stars whose position was known from
the Guide Star Catalog. The galaxy-star classification was done using
the east-west FWHM. Then every candidate galaxy was visually
inspected.
Important Notice:
The published coordinates have errors (up to 6" in the worst case):
this is due to a charge smearing problem, which correlates with
magnitude. The coordinates in this version are the corrected ones.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 42 1053 *The galaxy catalog
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Note on table.dat: Galaxy number 357 has been removed in the
electronic table.
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Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID *[1/1054]+ Number as in the published version
6- 7 I2 h RAh [11/16]+= 1950 Right Ascension
9- 10 I2 min RAm 1950 Right Ascension minutes
12- 17 F6.3 s RAs 1950 Right Ascension seconds
20- 21 I2 deg DEd [29/29] 1950 Declination degrees
23- 24 I2 arcmin DEm 1950 Declination minutes of arc
26- 30 F5.2 arcsec DEs 1950 Declination seconds of arc
32- 36 F5.2 mag Mag Magnitude
37 A1 --- u_Mag Uncertainty Flag on Magnitude
38- 42 F5.1 arcsec Ap Aperture radius used to compute Mag
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Note on ID: the galaxy number 357 is missing in the electronic table:
galaxies 357 and 358 seem identical in the printed table.
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History:
* July 1994: the first version was prepared by N. Paul. M. Kuin [NSSDC/ADC]
and M. Nonino [Trieste].
* December 1996: the ID number was added at CDS (P. Dubois)
Acknowledgements:
This work has been supported by NSF Grant No. AST 8451724, Nato Grant No.
CRG 901016, and a donation from the Digital Equipment Corporation
(End) N. Paul. M. Kuin [NSSDC/ADC] and M. Nonino [Trieste] 05-Dec-1996