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			THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS 
				25 Birch Street, Cambridge, MA 02138 USA
				BITNET: aavso@cfa8 SPAN: nssdca::cfa8::aavso
					Tel. 617-354-0484	FAX 617-354-0665

				AAVSO ALERT NOTICE 146 (July 19,1991)

SPECIAL MULTIWAVELENGTH MONITORING OF 0201+14 TT ARIETIS

The interesting cataclysmic variable 0201+14 IT Arietis will be the observing 
target of multiwavelength monitoring starting 8:00 UT August 1 and continuing for 
24 hours (!). This cataclysmic variable will be observed with the x-ray satellite 
ROSAT and also possibly with coordinated observations with the Japanese x-ray 
satellite Ginga and the ultraviolet satellite IUE.

We have been requested to monitor this star closely before the observing run, and 
in particular during the 24 hours of the multiwavelength campaign. Observers with 
photometers are urged to monitor IT Ari, with high speed photometry, if possible, 
to detect the possible flares that have been recorded for this star.

It is essential for everyone monitoring this star to record the exact timing of 
their observations. Visual observers should report the time to the minute (4 
decimal places of the JD). Photometric observers should report the time to the 
second (5 decimal places of the JD). Therefore, particularly those doing photometry 
should have an accurate clock for timing their observations. Accurate timing is 
essential because in the flaring activities of this star, an optical and x-ray 
time lag of about 60 seconds has been detected in cross correlation, and it is 
this aspect of TT Ari that is of particular interest during the multiwavelength 
monitoring campaign.

Below I am enclosing the information (from Jensen et al., 1983, ApJ, 270, 211) 
circulated by Dr. France Cordova, who is coordinating the multiwavelength campaign.

			"Optical Variability Tune Scales for IT Ari
			
1. A roughly sinusoidal orbital modulation is detected on a time scale of about 
12,000s (the variation in B magnitude was from 11.5 to 11.9 mag). I believe the 
source is somewhat brighter now (V= ~10.7).

2. Persistent optical flickering occurs with an amplitude of ~ 0.2 mag on a time 
scale of several minutes.

3. Transient optical oscillations occur with periods ~ 32s and ~ 12s.

4. An optical/X-ray time lag is detected in cross-correlations with a delay time 
of 60 seconds."

Unfortunately, IT Ari is not very favorably placed at this time. On August 1, it 
will be in the early morning sky and the Moon will be only 10 degrees away. Please 
try to monitor this star closely, and inform us of its optical behavior, in 
particular if there are any changes in brightness. This star has been in its 
bright state at about visual magnitude 10.6 since 1985. Please use the enclosed 
AAVSO finder chart in making your observations.

1247-28 EX HYDRAE

We have been informed by ROSAT astronomers that the x-ray satellite ROSAT detected 
very high x-ray emission from 1247-28 EX Hydrae on July 17. Danie Overbeek from 
South Africa informed us that the optical brightness of this star was at its 
usual magnitude of 13.0 at 17 UT on July 17, and that the brightness had not 
changed for about the past two months.

Observers are requested to use the enclosed AAVSO finder chart to keep a close 
eye on EX Hya and to inform us of any changes in its brightness.

The Headquarters answering machine (617-354-Q484) is on nights and weekends for 
your convenience.

My very sincere thanks for your efforts and valuable observations.

Good observing!

Janet A. Mattei
Director

Keywords:
AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484