Spectroscopic follow-up of transient Gaia19bwn
ATel #12911; T. Pursimo (NOT), Francisco Galindo-Guil (NOT), M. Dennefeld (IAP-Sorbonne University) and the OPTICON school "Observational Astrophysics: from proposals to publication" PhD students L. Ighina (Universita degli Studi Milano-Bicocca), N. Ihanec (Warsaw University Astronomical Observatory), N. Mandarakas (University of Crete ), K. Skillen (The University of Dublin), S. Terefe (Ethiopian Space Science and Technology Institute)
on 8 Jul 2019; 15:42 UT
Credential Certification: Tapio Pursimo (tpursimo@not.iac.es)
We report spectroscopic follow-up of a transient Gaia19bwn detected by
Gaia Science Alerts program on 2019-04-24. This is
associated with J113323.97+550415.9 (classified as QSO by the
SDSS-survey) located 6" SE from the core of the galaxy UGCA 239
(Markarian 177 or J113323.47+550420.6), both at redshift 0.009.
We obtained low resolution spectrum
2019-05-29 with ALFOSC on Nordic Optical Telescope (NOT)
in La Palma, Canary Island, with the spectral range of 3700-9200
A at a resolution of R=330.
The spectrum is dominated by the strong slightly broadened Balmer lines.
The Balmer lines are clearly visible down to Hη (transition 9-2, observed
wavelength 3866 Å) in contrast to
the SDSS spectrum where the Blamer lines
are visible down to Hδ. In the SDSS spectrum the
Hβ and [OIII](5007) have similar fluxes,
however now we find that HΒ flux is more than four times
the one of [OIII](5007). The Gaia data and our spectrum indicate
that the target got bluer during the out burst,
following the well-established characteristic of AGN
"bluer-when-brighter" trend.
We note that our data is obtained near the Gaia light curve
maximum (21-05-2019, G=17.37 and also 22-05-2019 ATEL #12794 g=17.6),
however the most recent
Gaia measurement (20-06-2018) is almost two magnitudes fainter
(G=19.23).
Follow up observations are strongly encouraged in all bands.
Lines identified (rest frame):
H I: 3830, 3889, 3967, 4099, 4340, 4859, 6564 Å
[O III]: 5007 Å
