J/ApJ/955/140 New optical light curves of PS J0147+4630 (Shalyapin+, 2023)
Andromeda's Parachute: time delays and Hubble constant.
Shalyapin V.N., Goicoechea L.J., Dyrland K., Dahle H.
<Astrophys. J., 955, 140 (2023)>
=2023ApJ...955..140S 2023ApJ...955..140S
ADC_Keywords: Gravitational lensing; Photometry; Optical; QSOs
Keywords: Quasars ; Strong gravitational lensing
Abstract:
The gravitational lens system PS J0147+4630 (Andromeda's Parachute)
consists of four quasar images ABCD and a lensing galaxy. We obtained
r-band light curves of ABCD in the 2017-2022 period from monitoring
with two 2m class telescopes. Applying state-of-the-art curve-shifting
algorithms to these light curves led to measurements of time delays
between images, and the three independent delays relative to image D
are accurate enough to be used in cosmological studies (uncertainty of
about 4%): ΔtAD=-170.5±7.0, ΔtBD=-170.4±6.0,
and ΔtCD=-177.0±6.5days, where image D is trailing all the
other images. Our finely sampled light curves and some additional
fluxes in the years 2010-2013 also demonstrated the presence of
significant microlensing variations. From the measured delays relative
to image D and typical values of the external convergence, recent lens
mass models yielded a Hubble constant that is in clear disagreement
with currently accepted values around 70km.s-1Mpc-1. We discuss how
to account for a standard value of the Hubble constant without
invoking the presence of an extraordinary high external convergence.
Description:
We monitored PS J0147+4630 with the 2.0m Liverpool Telescope (LT) from
2017 August to 2022 October using the IO:O optical camera with a pixel
scale of ∼0.30". Each observing night, a single 120s exposure was
taken in the Sloan r-band filter, and over the full monitoring period,
212 r-band frames were obtained.
The optical monitoring of PS J0147+4630 with the 2.5m Nordic Optical
Telescope (NOT) spanned from 2017 August to 2019 December. We used the
ALFOSC camera with a pixel scale of ∼0.21" and the R-Bessel filter.
This passband is slightly redder than the Sloan r band. Each observing
night, we mainly took three exposures of 30 s each under good seeing
conditions. The FWHM of the seeing disk was about 1.0" (we also
estimated FWHM seeing = 1.35"±0.15" from LT frames), and we
collected 298 individual frames over the entire monitoring campaign.
See Section 2 for further explanations.
Objects:
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RA (ICRS) DE Designation(s)
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01 47 10.20 +46 30 40.5 PS J0147+4630 = NAME Andromeda's Parachute
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 77 267 New r-band light curves of PS J0147+4630ABCD and the
control star S.
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See also:
J/MNRAS/465/4914 : R-band light curves of HE 0435-1223 (Bonvin+, 2017)
J/A+A/605/L8 : Spectra of lensed QSO PSOJ0147 (Lee, 2017)
J/MNRAS/467/4220 : Galaxies inside 120 arcsec of HE 0435-1223 (Rusu+, 2017)
J/A+A/616/A183 : R-band light curves of PG 1115+080 (Bonvin+, 2018)
J/ApJ/887/126 : Follow-up of PSJ0147+4630 lens system (Goicoechea+, 2019)
J/ApJ/905/7 : g- & r- LCs of Q0957+561 & SBS0909+532 (Cornachione+, 2020)
J/A+A/637/A89 : QSO 2237+0305 photometry & light curves (Goicoechea+, 2020)
J/A+A/640/A105 : R-band light curves of 23 lensed QSOs (Millon+, 2020)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 d JD [7970/9883] Julian Date of Observation,
JD-2450000.5
10- 15 F6.3 mag rmagA [15.89/16.06] r-band SDSS magnitude of quasar
image A
17- 21 F5.3 mag e_rmagA [0.004/0.03] Uncertainty in rmagA
23- 28 F6.3 mag rmagB [16.15/16.33] r-band SDSS magnitude of quasar
image B
30- 34 F5.3 mag e_rmagB [0.005/0.03] Uncertainty in rmagB
36- 41 F6.3 mag rmagC [16.45/16.66] r-band SDSS magnitude of quasar
image C
43- 47 F5.3 mag e_rmagC [0.006/0.04] Uncertainty in rmagC
49- 54 F6.3 mag rmagD [18.16/18.39] r-band SDSS magnitude of quasar
image D
56- 60 F5.3 mag e_rmagD [0.008/0.05] Uncertainty in rmagD
62- 67 F6.3 mag rmagS [15.38/15.46] r-band SDSS magnitude of control
star S
69- 73 F5.3 mag e_rmagS [0.004/0.05] Uncertainty in rmagS
75- 77 A3 --- Tel Telescope used; "LT" (Liverpool Telescope) or
"NOT" (Nordic Optical Telescope)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 02-Dec-2025