UBV photometry: The 60 cm telescope and the pulse-counting photometer at the Crimean Laboratory of the Sternberg Astronomical Institution (Ukraine) has been used for the photometric monitoring of TTS, including RY Tau, since 1965. Comparison stars and their magnitudes are given in Zajtseva et al. (1974). The diaphragm used was ; the typical error of the measurements is about .
UBVRI photometry and polarimetry: The 1.25 m telescope equipped with a five-channel photometer-polarimeter at the Crimean Astrophysical Observatory (Ukraine) was used for observations of RY Tau from December 1996 to March 1997. The diaphragm was . UBVRI magnitudes of RY Tau were determined with respect to the comparison star SAO 76567 = BD , for which we determined V, B-V , U-B , V-R , V-I , using the photometric standard BD (K3 V, V) from the list of Neckel & Chini (1980).
Spectroscopy: The high-resolution échelle spectrograph SOFIN at the 2.56 m Nordic Optical Telescope (La Palma, Spain) was used. The spectral range covered was 4500-9000 Å, the resolving power 25 000. For a typical spectrum, the S/N ratio was 100-200 longward of 5000 Å. One spectrum of RY Tau was taken at low brightness of the star on 4/5 Dec 1995, and several spectra were taken at high brightness during 20 Nov-01 Dec 1996. At low brightness in Dec 95, the star varied smoothly from V to ; the nearest photometric measurement was obtained 4 days after the spectrum; we interpolate the brightness to V at Dec 04, 1995. At high brightness, the first échelle spectrum was taken on Nov 20/21, 1996, at V, simultaneously with photometry (see Fig. 2). The spectra of 84 Her (G1 III), 27 Ari (G5 III-IV), 70 Peg (G7 III) and Eri (K0 IV) were taken for comparison purposes.
Several spectra of RY Tau in the regions of H and Na D were also taken at the coudé spectrograph of the 2.6 m Shajn reflector at the Crimean Astrophysical Observatory, with a resolving power of 40 000.
The journal of our spectroscopic observations is presented in Table 1.
© European Southern Observatory (ESO) 1999
Online publication: December 4, 1998