[vsnet-alert 5185] RE: on FBS 2351+228

[Rafael Costero Gracia <costero@astroscu.unam.mx>]

Dear Tonny and vsneters,

Through thin cloud and under very bright moon, we have just got a 2048x2048
CCD Echelle spectrum of FBS2351+228 in the 470-870 nm spectral range, at the
San Pedro Martir National Observatory 2.1 m telescope. The 30 minute exposure
mean-time was Aug 14.35 UT. The spectral dispersion and resolution at H alpha
are about 0.137 A/pix and 3.6 pixels (FWHM), respectively.

The continuum of the object is just above the solar (Moon reflected) spectrum
in the red portion, and invisible in the green (H beta) one. No reduction has
been made and the absorption lines (if any) are hidden in the solar spectrum
and read-out noise.

Nevertheless, there is no doubt that H ALPHA  IS IN EMISSION, and it is wider
than the He-Ar comparison lamp and teluric [O I] lines. Although the signal
under the line is very low (some 15 counts at the peak, above bias + sky
+ continuum), I did a rough estimate of its FWHM. I got 8.4+-0.4 pixels. After
deconvoluting and transforming, it turns out to be about 7.6+-0.5 pixels,
or 1.04+-0.07 Angstroms (47.5+-3 km/s). I do not dare estimate the with at
the base of the line!

H beta is barely visible, also in emission. Being near at the edge of the CCD
(surely vigneted), it will probably show much better if we again observe the
object tomorrow night, when we will probably shift the Echelle towards the
blue, to cover the 400-700 nm spectral range, at least.

The only thing I may add without any doubt is that there are no [OIII] (5007)
or [N II] (6584) forbidden lines. So this object is NOT a symbiotic star, as
far as my rather restricted knowledge can tell.

My sincere gratitude to the fellow astronomers who kindly accepted to spare
part of their observing night in order to obtain the described spectrum:
Hector Casta~neda and Maria J. Arevalo, from the Instiuto de Astronomia, UNAM,
and Instituto Astrofisico de Canarias, respectively. And I do appreciate your
timely anouncement of the bightenning of this object and kind report of its
yesterday bightness. Please do keep us informed of any changes observed in this
star during the next few days. And excuse my spelling; no dictionary or English
spelling checker here. Sorry.

Best regards,
Rafael Costero
Instituto de Astronomia, UNAM, Mexico

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