J/ApJ/551/973 Variables near SN 1991T in NGC 4527 (Saha+, 2001)
Cepheid calibration of the peak brightness of type Ia supernovae.
X. SN 1991T in NGC 4527.
Saha A., Sandage A., Thim F., Labhardt L., Tammann G.A., Christensen J.,
Panagia N., Macchetto F.D.
<Astrophys. J. 551, 973 (2001)>
=2001ApJ...551..973S 2001ApJ...551..973S
ADC_Keywords: Stars, variable ; Photometry ; Stars, distances
Keywords: Cepheids - distance scale - galaxies: individual (NGC 4527) -
supernovae: individual (SN 1991T)
Abstract:
Repeated imaging observations have been made of NGC 4527 with the
Hubble Space Telescope between 1999 April and June, over an interval
of 69 days. Images were obtained on 12 epochs in the F555W band and on
five epochs in the F814W band. The galaxy hosted the Type Ia supernova
SN 1991T, which showed relatively unusual behaviour by having both an
abnormal spectrum near light maximum, and a slower declining light
curve than the prototypical Branch-normal SNe Ia. A total of 86
variables that are putative Cepheids have been found, with periods
ranging from 7.4 days to over 70 days.
Objects:
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RA (2000) DE Designation(s)
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12 34 10.3 +02 39 56 SN 1991T
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 24 66 Position of the Variable Stars on U42G0101R
and U42G0102R images identified in the HST
data archive
table3.dat 38 1122 Photometry of variable stars:
magnitudes and error estimates
table4.dat 69 66 Characteristics of the Cepheids
table5.dat 42 66 DoPHOT and ROMAFOT mean magnitudes in V and I of
66 Cepheid candidates
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2001)
J/ApJ/522/802 : Cepheid calibration of SN 1989B in NGC 3627 (Saha+, 1999)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- [SST2001] Object identification in a Chip number-Variable
number format (CN-VNN)
9- 14 F6.2 pix Xpos X position
17- 22 F6.2 pix Ypos Y position
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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 --- [SST2001] Object identification in a Chip number-Variable
number format (CN-VNN)
8- 12 A5 --- Filt Filter name, F555W (∼V band) or F814W (∼I band)
14- 25 F12.4 d HJD Heliocentric Julian date
27- 31 F5.2 mag mag ? WFPC Filt band magnitude
33- 36 F4.2 mag e_mag ? Uncertainty in mag
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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 --- [SST2001] Object identification in a Chip number-Variable
number format (CN-VNN)
8- 13 F6.3 d Per Period
14 A1 --- u_Per Uncertainty flag on Per
16- 21 F6.3 mag Vmag ? Mean V band magnitude
23- 27 F5.3 mag e_Vmag ? Magnitude scatter in Vmag
29- 34 F6.3 mag Imag ? Mean Ic band magnitude
36- 40 F5.3 mag e_Imag ? Magnitude scatter in Imag
42- 47 F6.3 mag ModV ? Apparent distance modulus from Vmag (1)
49- 54 F6.3 mag ModI ? Apparent distance modulus from Imag (2)
56- 61 F6.3 mag ModT ? True distance modulus, corrected for
normal extinction (3)
63- 66 F4.2 mag e_ModT ? The RMS uncertainty in ModT
68 I1 --- q_[SST2001] Light-curve quality index on [SST2001] (4)
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Note (1): ModV = 2.76*log(Per) + 1.40 + Vmag
Note (2): ModI = 3.06*log(Per) + 1.81 + Imag
Note (3): ModT = ModV - R' * (ModV - ModI) where R' is the ratio of total to
selective absorption. See equation 5.
Note (4): Prescription given in Paper V (Saha et al., 1996ApJ...466...55S 1996ApJ...466...55S)
and ranges from 0 to 6.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- [SST2001] Object identification in a Chip number-Variable
number format (CN-VNN)
9- 14 F6.3 mag <Vmag>d DoPHOT mean V magnitude
16- 21 F6.3 mag <Imag>d ? DoPHOT mean I magnitude
23 I1 --- q_<Vmag>d ? DoPHOT quality index
25- 29 F5.2 mag <Vmag>r ? ROMAFOT mean V magnitude
31- 35 F5.2 mag <Imag>r ? ROMAFOT mean I magnitude
37 I1 --- q_<Vmag>r ? ROMAFOT quality index
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History:
From electronic version of the journal
References:
Saha et al., Paper V 1996ApJ...466...55S 1996ApJ...466...55S
Saha et al., Paper VI 1996ApJS..107..693S 1996ApJS..107..693S
Sandage et al., Paper VII 1996ApJ...460L..15S 1996ApJ...460L..15S
Saha et al., Paper VIII 1997ApJ...486....1S 1997ApJ...486....1S
Saha et al., Paper IX 1999ApJ...522..802S 1999ApJ...522..802S, Cat. J/ApJ/522/802
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 30-Aug-2001