VI/112 Optical Imaging of 57 spiral galaxies (Knapen+ 2004)
Structure and star formation in disc galaxies.
I. Sample selection and near-infrared imaging.
II. Optical Imaging of 57 spiral galaxies.
Knapen J.H., de Jong R.S., Stedman S., Bramich D.M., Folkes S.L.,
Bradley T.R.
<Mon. Not. R. Astron. Soc. 344, 527 (2003)>
<Astron. Astrophys. 426, 1135 (2004) >
=2003MNRAS.344..527K 2003MNRAS.344..527K
=2004A&A...426.1135K 2004A&A...426.1135K
ADC_Keywords: Galaxies, optical ; Galaxies, IR ; Photometry
Keywords: galaxies: spiral - galaxies: structure - infrared: galaxies -
methods: data analysis - techniques: image processing
Abstract:
We present optical observations of a sample of 57 spiral galaxies and
describe the procedures followed to reduce the data. We have obtained
images in the optical B and I broad bands, as well as in Hα,
with moderate spatial resolution and across wide enough fields to
image the complete disks of the galaxies. In addition, we observed 55
of our sample galaxies in the R and eight in the V band, and imaged a
subset through a dedicated narrow continuum filter for the Hα
line. We describe the data reduction procedures we developed in the
course of this work to register, combine and photometrically calibrate
each set of images for an individual galaxy. We describe in some
detail the procedure used to subtract the continuum emission from our
Hα images. In companion papers, we describe near-infrared
imaging of the galaxy sample, and present analyses of disk scale
lengths, and of properties of bars, rings, and HII regions in the
sample galaxies. The images described here will be made available for
use by other researchers through the CDS.
Description:
All B, R, I and Hα images described in the paper are presented
electronically, along with the Ks images from Paper I (Knapen et al.,
2003MNRAS.344..527K 2003MNRAS.344..527K). The images are in FITS format, with basic
parameters like pixel scale and calibration described in the FITS
headers. All images have been reduced to the equivalent of 1 second
exposure time. The filenames have the basic format ngc1234X.fits,
where digits 4-7 identify the galaxy's NGC number, which is followed
by a description of the filter used (B, V, R, I, K, Ha [not continuum
subtracted], Hacs [continuum subtracted], or HaCont for the 6470/115
continuum filter). Further details on, e.g., exposure times,
telescopes and filters used, or Ha continuum subtraction can be found
in the papers.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 131 57 Global parameters of the galaxies
images.dat 193 57 Image filenames
fits/* . 352 All FITS images
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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- 5 A5 --- NGC NGC galaxy identification number
7- 12 A6 --- MType Morphological type (1)
14- 17 F4.1 arcmin D25 Apparent major isophotal diameter (1)
19- 20 I2 --- ArmClass Spiral arm class (2)
22- 23 I2 deg i Inclination (1)
25- 27 I3 deg PA ? Position angle of disk major axis (1)
29- 34 F6.2 mag BMAG Total absolute B-magnitude (1)
36- 39 I4 km/s RV Mean heliocentric radial velocity (1)
41- 44 F4.1 Mpc Dist Distance (3)
46- 48 I3 pc/arcsec scale Image scale
50- 51 I2 min Bexp B-band exposure time
53- 54 I2 min Rexp ? R-band exposure time
56- 57 I2 min Iexp ? I-band exposure time
59- 60 I2 min Ksexp ? Ks-band exposure time
62- 64 I3 min Haexp H-alpha exposure time
66- 68 F3.1 arcsec BSeeing B-band seeing
70- 72 F3.1 arcsec RSeeing ? R-band seeing
74- 76 F3.1 arcsec ISeeing ? I-band seeing
78- 81 F4.2 arcsec KsSeeing ? Ks-band seeing
83- 85 F3.1 arcsec HaSeeing H-alpha seeing
87- 93 A7 --- HaFilt Filter used for H-alpha imaging
95-109 A15 --- HacsFilt Filter used for continuum imaging
111-115 F5.3 --- HaScale ? Scale factor used to subtract the
continuum from H-alpha.
117-120 F4.1 arcmin KsSize Size of Ks-band image
122-130 A9 arcmin Size Size of optical images
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Note (1): From de Vaucouleurs et al., RC3 (1991, Cat. VII/155)
Note (2): From Elmegreen & Elmegreen (1987ApJ...314....3E 1987ApJ...314....3E)
Note (3): From Tully, NGC (1988, Cat. VII/118)
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Byte-by-byte Description of file: images.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- NGC NGC galaxy identification number
8- 30 A23 --- B B image
32- 54 A23 --- Ha Hα image
56- 78 A23 --- HaCont Hα image for the 6470/115 continuum filter
80-102 A23 --- Hacs Hα image, continuum subtracted
104-126 A23 --- I I-band image
128-150 A23 --- K K-band image
152-174 A23 --- R R-band image
176-198 A23 --- V V-band image
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(End) Johan Knapen [University of Hertfordshire, U.K.] 03-Sep-2004