SIMBAD references

We report on a search conducted for variability in the Hα emission line of the recurrent nova T CrB with a time resolution of 10-15 minutes. This is comparable to the timescale of the photometric flickering observed in this object. This is the first time that observations of the short-timescale emission-line variation have been made for this system. On two nights (1999 January 6 and 7), we detected statistically significant variability (at the 99% confidence level) in the Hα line profile. This variability is confined to the central part of the emission line (±100 km/s), although FWZI(Hα)∼800 km/s. The variability in the line profile is accompanied by variability of the total equivalent width, EW(Hα): ±8% for 1999 January 6 and ±6% for 1999 January 7 (calculated from the mean EW value). Assuming Keplerian motion, the variability is generated at a distance of ∼20-30 R_☉ from the white dwarf, which is approximately the radius of the ring that the stream of gas forms as it flows away from the L1 Lagrangian point. For three other nights we are only able to put upper limits on the variability, ΔEW(Hα): ±2% for 1998 April 15, ±4% for 1998 August 2, and ±3% for 1998 August 3.