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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 
			INTERNET: aavso@cfa0.haivard.edu 
		Tel. 617-354-0484	FAX 617-354-0665


		AAVSO ALERT NOTICE 174 (July 22,1993)

UPDATE ON ORFEUS MISSION

The launch of NASA's Space Shuttle Discovery was scrubbed on July 17 due to telemetry 
indicating that a capacitor used for firing one of the explosive bolts had charged 
prematurely. Discovery is now re-scheduled to be launched on Saturday morning, July 22, 
1993. The ORFEUS mission will be deployed from Discovery and retrieved for return to 
Earth (see AAYSO Alert Notice 173). You will be able to follow the mission on NASA 
Select, if your local TV cable company carries this station.

Last week we mailed to AAVSO members and observers the NASA/DAPA pamphlet on 
the ORFEUS Mission mentioned in AAYSO Alert Notice 173 along with a special message 
from Dr. R. Stachnik, the ORFEUS-SPAS Program Scientist at NASA Astrophysics 
Division.

Observations of cataclysmic variables with ORFEUS will start two to three days after the 
launch of Discovery. Please continue to monitor closely the stars that are the primary 
observing targets during the mission, i.e., 0058+40 RX And, 0409-71 VW Hyi, 0814+73 Z 
Cam, 1813+49 AM Her, 2138+43 SS Cyg, and 2209+12 RU Peg. These stars should be 
monitored between now and the end of the nine-day mission, or the end of July, whichever 
is later (in case there are further delays with the launch). Call in your observations of them 
to AAVSO Headquarters using the charge-free 800 number (800-642-3883). In addition to 
the primary observing targets, if any of the brighter dwarf novae go into outburst, i.e. 
magnitudes brighter than 12.5 at outburst, please inform AAVSO Headquarters, as these 
stars may also be observed during the ORFEUS mission.

Below is the status of the primary observing targets at this time: 
0058+40 RX And - coming down from recent outburst 
0409-71	VW Hyi - coming down from recent narrow outburst 
0814+73 Z Cam  - at standstill 
1813+49 AM Her - in its bright state 
2138+43 SS Cyg - in quiescence; there is a good possibility that SS Cyg may go into 
			outburst during the mission, so please monitor very closely 
2209+12 RU Peg - at quiescence

We very much appreciate your enthusiastic monitoring of the above stars and other 
cataclysmic variables for this mission. We extend our thanks to the following observers 
who have been telephoning, faxing, or emailing their observations to AAVSO 
Headquarters: W. Albrecht, J. Bortle, W. Dillon, E. Halbach, J. Hers (for R. W. Jones, J. 
A. Smit), R. King, J. McKenna, J. Nordby, D. Overbeek, G. Poyner, P. Robbins, R. Royer, 
G. Sarty, E. Schweitzer (for M. Verdenet), S. Sharpe, and R. Stewart.

Your observations of and notifications about cataclysmic variables for the ORFEUS 
mission are vital to the success of space research being done in this area during this 
pioneering mission!

REQUEST FOR CONTINUED MONITORING OF 0409-71 VW HYDRI 
AND 2138+43 SS CYGNI

Astronomers at Lawrence Livermore National Laboratories are requesting our continued 
assistance in monitoring SS Cyg and VW Hyi throughout the rest of 1993, in order to 
schedule observations of the outbursts of these stars with the Extreme Ultraviolet Explorer 
EUVE). The Hubble Space Telescope (HST) is also being scheduled to observe VW Hyi 
(see AAVSO Alert Notice 173). Please continue to keep a close eye on these bright dwarf 
novae and call in your observations whenever observers in the northern hemisphere see SS 
Cyg go into outburst or observers in the southern hemisphere see VW Hyi go into outburst.

REQUEST TO CONTINUE TO MONITOR 1813+49 AM HERCULIS

Astronomers at Villanova University are requesting our assistance in continuing to monitor 
AM Her, in order to provide data for the scheduling of observations of this star with the 
HST in the coming few months. Throughout the rest of 1993, please keep a close eye on 
AM Her and telephone your observations to AAVSO Headquarters, keeping us informed 
of its brightness.

UPDATE ON 1910-33 RY SAGITTARII

The R CrB star RY Sgr, which started to fade in mid-June (see AAUSO Aleft Notice 173), 
has faded dramatically. It was fainter than magnitude 13 on July 22, as reported by J. 
Bortle.

REMINDER OF REQUEST TO MONITOR 1834-23 V348 SAGITTARII

Please continue to monitor the interesting star V348 Sgr, whose behavior resembles that of 
R CrB, and inform us when it becomes brighter than magnitude 13.0, so we may inform 
astronomers at Louisiana State University (see AAYSO Alert Notice 173).

Sincere thanks to you for your dedication and enthusiasm, and for your valuable 
contributions to variable star research.

Clear skies and good observing,

Janet A. Mattei 
Director

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