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J/ApJS/128/99 HST photometry of 4 Virgo LSB galaxies (O'Neil+, 2000)
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Structural characteristics of faint galaxies serendipitously discovered
with the Hubble space telescope WFPC2.
O'Neil K., Bothun G.D., Impey C.D.
<Astrophys. J. Suppl. Ser. 128, 99 (2000)>
=2000ApJS..128...99O
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ADC_Keywords: Galaxies, photometry ; Photometry, ultraviolet
Mission_Name: HST
Keywords: galaxies: elliptical and lenticular, cD - galaxies: evolution -
galaxies: irregular - galaxies: photometry - galaxies: spiral -
surveys
Abstract:
Utilizing the F814W and F300W filters, Hubble Space Telescope Wide
Field Planetary Camera-2 (WFPC2) images were taken of four low surface
brightness galaxies in the direction of the Virgo Cluster - V7L3,
V2L8, V1L4, and Malin 1. The high resolution of the WFPC2 combined
with the extremely diffuse nature of the four galaxies makes them
essentially transparent, allowing for the serendipitous discovery of
139 background galaxies visible through both the disks and nuclei of
the foreground galaxies. Surface photometry was done on the newly
discovered galaxies through the F814W (I-band) filter. The detected
galaxies have both r1/4 and exponential-type profiles with radii (to
the {mu}_F814W_=25.0mag/arcsec^2^ limit) less than 5.0". Their total
magnitudes range from 18.9 through the survey cutoff at 25.0 in the
F814W filter.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 45 141 Aperture magnitudes
table3.dat 93 139 Photometry for all galaxies in this study
table4.dat 31 27 Colors of the 29 galaxies detected on the ground
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See also:
J/A+AS/127/367 : Virgo Photometry Catalogue (VPC) (Young+ 1998)
Table 1: J2000 Coordinates for the surveyed fields
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Field RA (2000) DE Date Simbad designation(s)
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V2L8 12:31:27.1 14:37:14.1 01/05/96 [IBM88] V02L08
V7L3 12:29:06.2 12:53:34.7 03/08/97 VCC 1149
V1L4 12:34:52.3 14:12:21.3 03/10/96 IC 3524
Malin 1 12:37:08.8 14:18:45.9 03/10/96 Malin 1
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- OBI2000 Galaxy name ([[OBI2000] NNN-NN or mN-NN)
8- 11 F4.1 mag m0.5" ? Aperture magnitude at radius of 0.5"
in F814W band
13- 16 F4.1 mag m1.0" ? Aperture magnitude at radius of 1.0"
in F814W band
18- 21 F4.1 mag m2.0" ? Aperture magnitude at radius of 2.0"
in F814W band
23- 26 F4.1 mag m3.0" ? Aperture magnitude at radius of 3.0"
in F814W band
28- 31 F4.1 mag m4.0" ? Aperture magnitude at radius of 4.0"
in F814W band
33- 36 F4.1 mag magtot ? Total isophotal magnitude in F814W band
37 A1 --- u_magtot ':' when magtot has an inaccuracy of 1mag
40- 42 F3.1 arcsec r25 ? Radius at the 25.0mag/arcsec^2^ isophote,
which is the same radii at in which the
isophotal magnitudes (magtot) were determined
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- OBI2000 Galaxy name ([[OBI2000] NNN-NN or mN-NN)
7 A1 --- Note [b-e] Note (1)
9- 10 I2 h RAh Right ascension (J2000.0)
12- 13 I2 min RAm Right ascension (J2000.0)
15- 19 F5.2 s RAs Right ascension (J2000.0)
21 A1 --- DE- Declination sign (J2000.0)
22- 23 I2 deg DEd Declination (J2000.0)
25- 26 I2 arcmin DEm Declination (J2000.0)
28- 31 F4.1 arcsec DEs Declination (J2000.0)
33 A1 --- MType Morphological type (2)
35 I1 --- Rating Scorecard rating
37- 41 F5.1 --- chi2B ? chi^2^ fit to the exponential profiles
(3)
43- 46 F4.1 --- chi2A ? chi^2^ fit to the r^1/4^-type profiles
(3)
48- 51 F4.1 mag rmag ? Total integrated isophotal magnitude of
the galaxy through the F814W filter
52 A1 --- u_rmag ':' when rmag has an inaccuracy of 1mag
55- 59 F5.2 mag 814-300 ? Isophotal 814-300 colour index
61- 64 F4.1 mag malpha ? Total integrated magnitude of the
galaxy (4)
66- 69 F4.1 mag/arcsec+2 SuBr0 ? Central surface brightness, when it was
possible to obtain this from the
profile fit. (5)
70 A1 --- u_SuBr0 ':' when SuBr0 inaccurate to 1mag/arcsec+2
73- 76 F4.1 mag/arcsec+2 SuBr0c ? Inclination corrected central surface
brightness, as
SuBr0c=SuBr0-2.5log[cos(i)]
77 A1 --- u_SuBr0c ':' when SuBr0c inaccurtce to 1mag/arcsec+2
80- 81 I2 deg i ? Inclination angle
83- 86 F4.1 arcsec alpha ? Exponential scale length
88- 90 F3.1 arcsec r25 ? Major axis radius as measured at the
SuBr_F814W_=25.0mag/arcsec^2^ isophote
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Note (1): Notes:
b: Appears to be interacting galaxies.
c: High errors are due to foreground star.
d: Galaxy at edge of image. Unable to obtain color/profile data.
e: Extremely noisy in this area of the image. All values
(other than R.A. and decl.) should not be trusted.
Note (2): Galaxy structural types were assigned to three categories based
strictly on profile fit and not on any morphological criteria.
These categories are as follows:
Class A: Pure r^1/4^-type profile
Class B: Good exponential fit with possible up- or downturn in the
inner regions - a subset of these galaxies will later be
fitted with a combined bulge+disk model.
Class C: No adequate fit to the profile
Note (3): Assuming the data has uniform error bars of +/-0.05mag/arcsec^2^
Note (4): malpha=SuBr0-2.5log(2{pi}alpha^2^), where
alpha is the exponential scale length (in arcsec) and
SuBr0 is the central surface brightness in mag/arcsec^2^
If an exponential profile was not fitted to a particular galaxy's
surface brightness profile, this column is left blank.
Note (5): Surface brightnesses are within 0.1mag/arcsec^2^,
unless otherwise noted. In the case of r^1/4^ profile galaxies, this
is the effective surface brightness
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- OBI2000 Galaxy name ([OBI2000] NNN-NN or mN-NN)
9- 13 F5.2 mag Vmag V magnitude
15 A1 --- l_B-V Limit flag on B-V
16- 20 F5.2 mag B-V ? B-V colour index
22 A1 --- l_V-I Limit flag on V-I
23- 26 F4.2 mag V-I ? V-I colour index
28- 31 F4.2 arcsec Rad Radius
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History: From ApJS electronic version
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(End) James Marcout, Patricia Bauer [CDS] 18-Sep-2000