Greetings, After running on Tau 3 until it set I turned the CCD camera onto EX Hydrae about 1145UT on Feb 7. The star appeared its normal brightness. Visual observers often seem unaware that this star is subject to both eclipses at about 98 minute intervals and white dwarf spin period fluctuations with a period of 67 minutes. The amplitude of the latter is usually between 0.3 and 0.7 magnitudes but I have seen it larger on a few occasions. On one occasion in 1968 it was almost flarelike. The eclipses are difficult to see at times and the interaction between these and the spin humps, with variations in the mass flow rate, causes the brightness of EX Hydrae to be very erratic in quiescence. Outbursts are rare and very important! If you see the star brighter than V = 12 tell the world. Regards, Stan ---------- > From: Taichi Kato <tkato@kusastro.kyoto-u.ac.jp> > To: vsnet-alert@kusastro.kyoto-u.ac.jp > Subject: [vsnet-alert 4133] EX Hya brighert? (Pearce) > Date: Sunday, February 06, 2000 9:52 PM > > EX Hya brighert? (Pearce) > > From: "Andrew Pearce" <arpearce@ozemail.com.au> > Subject: EX Hya > Date: Mon, 7 Feb 2000 07:32:43 +0800 > > This may be another short period variation at minimum, however I have observed a > brightening of EX Hya as detailed below: > > Feb 5.806UT 13.1 > Feb 6.757UT 12.6 > > The observation on Feb 6th was made at 0210 hrs local time. Unfortunately it > clouded over shortly thereafter and I couldn't make any further observations > despite there being another 2 hours of dark time. > > Observations for the 30 days preceding Feb 5th show the star to have remained at > a relatively constant brightness around mag 13.1-13.2. Certainly no 0.5 mag > increase as is the case now. > > Hopefully I'll make further observations tonight. > > Regards > Andrew Pearce (PEX) > > --- > > HYAEX 20000205.806 131 PEA > HYAEX 20000206.757 126 PEA >