Photometric and Spectroscopic observations of M31N 2007-11d
ATel #1299; R. Quimby (Caltech), A. Shafter (SDSU), A. Rau, M. Kasliwal, E. Ofek, (Caltech), F. Yuan, C. Akerlof (University of Michigan), and J. C. Wheeler (University of Texas)
on 22 Nov 2007; 04:37 UT
Credential Certification: Robert Quimby (quimby@astro.as.utexas.edu)
Subjects: Optical, Nova, Transient
We report on the independent detection and follow-up of the bright
optical transient M31N
2007-11d, which was first reported by S. Nakano et al. (IAUC
8898 ). The transient was detected in unfiltered ROTSE-IIIb images
taken around Nov. 19.13 UT at about 15.3 mag. It brightened to 14.7 mag
on Nov. 20.06.
We began photometric follow-up observations with the Palomar 60
inch telescope on Nov. 20.3886 and Nov. 21.0865 UT. Multiple images
were obtained in the gri'z' bands yielding the following detections
(calibrated against the SDSS):
JD-2400000.5 filter Magnitude
54424.3885637 g 15.24+-0.03
54425.0864711 g 15.40+-0.06
54424.3907901 r 15.13+-0.02
54425.0886947 r 15.20+-0.06
54424.3930187 i' 14.68+-0.04
54425.0909192 i' 15.05+-0.07
54424.3952417 z' 15.05+-0.05
54425.0961037 z' 14.97+-0.09
Thus the object has clearly faded in the g and i' bands.
No source was detected at this position in archival SDSS data to the
following limits:
filter uplim abs. mag limit*
g 21.82 -3.6
r 22.12 -3.0
i 21.53 -3.4
z 20.14 -4.7
(*) assuming D = 0.77 Mpc and corrected for Galactic
extinction (E[B-V] =0.268; Schlegel et al. 1998).
A spectrum (420-900 nm) obtained ~4 days post discovery on
Nov. 21.29 UT with the 9.2m Hobby-Eberly Telescope (+ Marcario
Low-Resolution Spectrograph) by J. Caldwell and A. Westfall shows
it likely to be a bright nova. The spectrum is characterized
predominately by narrow Balmer and Fe II emission features with P
Cygni profiles superimposed on a blue continuum. Overall, the
spectrum is similar to both the FeII nova M31N 2007-11c around
maximum (A. Rau in prep) and M31N 2007-07c 2.5 days after
discovery (ATel #1153).