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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 =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). 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:
FileName Lrecl Records Explanations
ReadMe 80 . This file table.dat 131 57 Global parameters of the galaxies images.dat 198 57 Image filenames fits/* 0 352 All FITS images
Byte-by-byte Description of file: table.dat
Bytes Format Units Label Explanations
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
Note (1): From de Vaucouleurs et al., RC3 (1991, Cat. VII/155) Note (2): From Elmegreen & Elmegreen (1987ApJ...314....3E) Note (3): From Tully, NGC (1988, Cat. VII/118)
Byte-by-byte Description of file: images.dat
Bytes Format Units Label Explanations
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

(End) Johan Knapen [University of Hertfordshire, U.K.] 03-Sep-2004
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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