Microlensing of GSC 3656-1328
ATel #943; M. Mikolajewski, T. Tomov, A. Niedzielski, A. Strobel, T. Brozek, K. Czart, C. Galan, A. Karska, E. Swiercznski, M. Wiecek, Torun Center for Astronomy, Nicolaus Copernicus University, Torun, Poland
on 14 Nov 2006; 15:09 UT
Credential Certification: Andrzej Niedzielski (email@example.com)
Subjects: Optical, Microlensing Event, Star, Variables
In our previous report (ATEL#931) we have suggested that the bright optical
transient in Cassiopeia, identified as GSC 3656-1328, can be understood as a
gravitational microlensing event of a nearby star (see also ATEL#942). All
available photometric data support the finding and a symmetric microlens fit best reproduces the light curve.
We continue our spectroscopic and photometric monitoring of GSC 3656-1328.
New spectra obtained in the 3700-7300AA region at a resolution of 4A with the
60/90cm Schmidt-Cassegrain Telescope (TSC) at Piwnice equipped with the Copernicus
Cassegrain Spectrograph (CCS) between 2006 November 4 and
November 10 show the same A0V-A1V spectral type as observed a few days
Additionally we have searched our database of prismatic spectra collected with the TSC
and identified the object on a Kodak IIa-O plate obtained with the F2
objective prism (dispersion about 260A/mm at H-gamma) on 1966 November
11.917 UT. Although the plate is of moderate quality
GSC 3656-1328 is easy to identify as a hot continuum object with strong Balmer absorptions similar to
other nearby A0 stars.
Our new photometric UBVRI observations obtained with the 60cm Cassegrain telescope and
SBIG STL-1001 camera show that changes of U-B, B-V, V-R and R-I between 2006
November 02 and November 10 are below 0.07, 0.03, 0.03 and 0.01 mag,
respectively i.e. within the observation uncertainties. The V magnitude is 10.48 on
2006 November 03.755 UT, 10.55 on November 03.979 UT and 11.22 on November
09.9 UT. The mean color index B-V=0.19 +/- 0.01 and remains constant. Six
hours monitoring of the object on 2006 November 09 in BV filters did not
show any remarkable changes.