J/ApJ/662/62 Optical monitoring of SDSS J1004+4112 (Fohlmeister+, 2007)
A time delay for the cluster-lensed quasar SDSS J1004+4112.
Fohlmeister J., Kochanek C.S., Falco E.E., Wambsganss J., Morgan N.,
Morgan C.W., Ofek E.O., Maoz D., Keeton C.R., Barentine J.C., Dalton G.,
Dembicky J., Ketzeback W., McMillan R., Peters C.S.
<Astrophys. J., 662, 62-71 (2007)>
=2007ApJ...662...62F 2007ApJ...662...62F
ADC_Keywords: QSOs ; Gravitational lensing ; Photometry
Keywords: cosmology: observations - gravitational lensing -
quasars: individual (SDSS J1004+4112)
Abstract:
We present 426 epochs of optical monitoring data spanning 1000 days
from 2003 December to 2006 June for the gravitationally lensed quasar
SDSS J1004+4112. The time delay between the A and B images is
ΔtBA=38.4±2.0days (Δχ2=4) in the expected sense
that B leads A and the overall time ordering is C-B-A-D-E. The
measured delay invalidates all published models. The models probably
failed because they neglected the perturbations from cluster member
galaxies. Models including the galaxies can fit the data well, but
conclusions about the cluster mass distribution should await the
measurement of the longer, and less substructure sensitive, delays of
the C and D images. For these images, a delay of
ΔtCB~=681±15days is plausible but requires confirmation,
while delays of δtCB>560days and δtAD>800 days are
required. We clearly detect microlensing of the A/B images, with the
delay-corrected flux ratios changing from mB-mA=0.44±0.01mag in the
first season to 0.29±0.01mag in the second season and 0.32±0.01mag
in the third season.
Description:
The photometric monitoring observations presented here took place
between 2003 December and 2006 June. The bulk of data were taken with
the 1.2m telescope at Fred Lawrence Whipple Observatory on Mount
Hopkins using the 4Shooter (R band, 93 epochs, 0.66"/pixels), Minicam
(SDSS r band, 74 epochs, 0.604"/pixels), and Keplercam (SDSS r band,
91 epochs, 0.672"/pixels, plus 4 epochs in R band) during the first,
second, and third season, respectively. Additional data were obtained
with the Apache Point Observatory (APO) 3.5m telescope using SPICam
(SDSS r band, 9 epochs, 0.282"/pixels), the MDM 2.4m Hiltner
telescope using the RETROCAM (SDSS r band, 27 epochs, 0.259"/pixels),
8K (R band, 12 epochs, 0.344"/pixels), Templeton (R band, 8 epochs,
0.275"/pixels) and Echelle (R band, 3 epochs, 0.275"/pixels)
detectors, the MDM 1.3m McGraw-Hill telescope using the Templeton
detector (R band, 6 epochs, 0.508"/pixels), the Palomar Observatory
1.5m telescope using the SITe detector (R band, 13 epochs,
0.379"/pixels), the Wise Observatory 1.0m telescope with the Tektronix
(R band, 30 epochs, 0.696"/pixels) and TAVAS (clear, 53 epochs,
0.991"/pixels) detectors, and the WIYN 3.5m telescope using the WTTM
(SDSS r band, 3 epochs, 0.216"/pixels) detector. The combined data set
consists of 426 epochs.
Objects:
---------------------------------------------------------------
RA (2000) DE Designation(s)
---------------------------------------------------------------
10 04 34.9 +41 12 42.8 SDSS J1004+4112 = QSO J1004+4112
---------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 89 426 Light curves for SDSS J1004+4112
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See also:
J/MNRAS/382/412 : Catalog of SDSS-DR5/2MASS spectroscopic quasars (Ofek, 2007)
J/AJ/132/999 : SDSS quasar lens search (Oguri+, 2006)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 F11.3 d HJD Heliocentric Julian Date
13- 18 F6.2 --- Rchi2 The χ2 divided by degrees of freedom (1)
20- 25 F6.3 mag ImAmag Image A magnitude (2)
27- 31 F5.3 mag e_ImAmag Uncertainty in Image A
32 A1 --- f_ImAmag [)] not used in the time delay estimates.
34- 39 F6.3 mag ImBmag Image B magnitude (2)
41- 45 F5.3 mag e_ImBmag Uncertainty in Image B
46 A1 --- f_ImBmag [)] not used in the time delay estimates.
48- 52 F5.3 mag ImCmag Image C magnitude (2)
54- 58 F5.3 mag e_ImCmag Uncertainty in Image C
60- 65 F6.3 mag ImDmag Image D magnitude (2)
67- 71 F5.3 mag e_ImDmag Uncertainty in Image D
73- 79 A7 --- Obs Observatory (4)
81- 89 A9 --- Det Detector
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Note (1): Indicates how well our photometric model fit the imaging data.
When χ2 > NDof we rescale the photometric errors presented in
this Table by (χ2/Ndof)1/2 before carrying out the time
delay analysis to reduce the weight of images that were fit poorly.
Note (2): Relative to the comparison stars (see text).
Note (4): Observatories as follows:
MDM = MDM 2.4m/1.3m Hiltner/McGraw-Hill telescopes
FLWO = 1.2m telescope at Fred Lawrence Whipple Observatory on Mount Hopkins
Wise = Wise Observatory 1.0m telescope
Palomar = Palomar Observatory 1.5m telescope
APO = Apache Point Observatory 3.5m telescope
WIYN = WIYN 3.5m telescope
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 16-Apr-2009