Optical and Near-IR Observations of the Current Outburst of Aql X-1
ATel #1218; D. Maitra (Univ. of Amsterdam), D. M. Russell (Univ. of Southampton), F. Lewis (Las Cumbres Observatory Global Telescope Network (LCOGTN)/Open Univ.), C. Bailyn (Yale Univ.), R. P. Fender (Univ. of Southampton), P. Roche (LCOGTN)
on 18 Sep 2007; 21:52 UT
Credential Certification: Dipankar Maitra (maitra@astro.yale.edu)
Subjects: Infra-Red, Optical, Binary, Neutron Star, Transient
As part of a monitoring campaign of quiescent and
outbursting low-mass X-ray binaries with the CTIO/SMARTS
telescopes and the Faulkes telescopes , we report
observations of Aql X-1 and confirm the optical
counterpart of the new X-ray outburst (ATel #1216).
On 2007 Aug 30 (MJD 54342.26) we performed
optical observations of Aql X-1 for 100 sec each in V and
i' filters using the Faulkes Telescope North in V
and i'-bands and detected the source with a confidence of
20 and 63 sigma in V and i', respectively. The apparent
magnitudes (flux calibrated using stars C1 and C2 in the
field of view;
Chevalier et al. 1999, A&A, 347, L51) are
V=18.71 +- 0.08; i'=17.28 +- 0.05. During a quiescent
period (8 observations between MJD 53833.6 and 54215.6)
before the May 2007 outburst (ATel #1079, #1080) we
measure V=19.21 +- 0.10; i'=17.74 +- 0.07 for Aql X-1
(all are > 5 sigma detections) which agree with the values
measured in April 1999 by
Chevalier et al. (1999).
As of the
latest observations using the CTIO/SMARTS 1.3m telescope
on September 18, 3.2h UTC (mid-exposure), the source was
at R=17.10 +- 0.05 mag and J=15.5 +- 0.1 mag, compared to
mean quiescent values of R=18.8 +- 0.09 mag and J=16.7 +-
0.10 mag. All magnitudes quoted above include the
unrelated star 0.5" away (Chevalier et al. 1999) of
magnitude V=19.42 +- 0.06; i'=18.02 +- 0.06 mag.
The OIR data from both telescopes show an
increasing trend in the V, R, i' and J band fluxes from
the source from 2007 Aug 29th (MJD 54341). Latest OIR and
ASM data however suggest that the increasing trend may
have arrested and the source might have reached peak or
near-peak luminosity. The latest fluxes are still lower
than the maximum observed peak fluxes from this source
during the FRED outburst of 2003 and 2000 by factors of
~3-5 at all wavelengths. Multiwavelength observations are
encouraged.
FL acknowledges support from the Dill Faulkes
Educational Trust.
The Faulkes light curves can be found at:
http://www.astro.soton.ac.uk/~davidr/faulkes/lc-aqlx1.png
and the SMARTS light curves at:
http://staff.science.uva.nl/~dmaitra/xrb/AqlX-1/AqlX-1.lc.jpg
