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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: aavsoGcfa0.harvard.edu
			   Tel. 617-354-0484	FAX 617-354-0665

		AAVSO ALERT NOTICE 176 (September 10, 1993)

FOURTH UPDATE ON ORFEUS MISSION

The launch of NASA's space shuttle Discovery, carrying the ORFEUS mission, was 
canceled for the third time on August 12, 1993, during the last minute before launch. 
NASA has rescheduled the launch of Discovery for September 12, 1993, after all shuttle 
systems have been thoroughly checked. Once Discovery is launched, the ORFEUS mission 
will be deployed and the observations of cataclysmic variables with ORFEUS will start two 
to three days after launch (see AA VSO Alert Notices 173, 174, and 175).

The primary observing targets for the ORFEUS cataclysmic variables observing program 
are still the same: 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. Please monitor these stars between now and 
the end of the nine-day mission, and call in your observations of them to the AAVSO, using 
the charge-free 800 number (800-ti42-3883). In addition to the primary observing targets, if 
any of the brighter dwarf novae go into outburst, i.e., magnitude 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 ORFEUS cataclysmic variable targets at this time:

0058+40 RX And - going through an outburst which started on September 5. 
0409-71	VW Hyi - no recent observations; probably at quiescence.
0814+73	Z Cam - continues in standstill.
1813+49	AM Her - continues in its bright state.
2138+43 SS Cyg	- reached minimum after an anomalous outburst that started 
			in mid-August.
2209+12 RU Peg - at quiescence.

In addition, 1640+25 AH Her has been undergoing an outburst, as reported by J.Bortle, W. 
Dillon, and R. Stewart. It was 11.5 on Sept. 7.1 UT.

Your observations and your notification on cataclysmic variables are vital to the success of 
research on these stars with the ORFEUS mission. Please continue your enthusiastic 
monitoring!

FADING OF 1544+28A R CORONAE BOREALIS

R Coronae Borealis, the prototype of its kind, has started to fade slowly. Beginning August 
24, it has faded from magnitude 6.0 to 7.5, as reported by J. Bortle, O. Cole Arnal, P. 
Collins, G. Comello, W. Dillon, P. Dombrowski, G. Dyck, O. Gabzo, B. Granslo, R. Hayes, 
L. Hiett, G. Lubcke, K. Medway, E. Ofek, A. Pereira, G. Poyner, P. Robbins, O. Shemmer, 
P. Schmeer, W. Sherman, C. Stephan, R. Stewart, D. Swann, D. Troiani, D. Weier, D. 
York, and G. Zajacz. The last small fading occurred in November 1991, when R CrB faded 
to magnitude 7 and stayed about magnitude 7 for about 30 days, and then brightened to 
maximum. Please monitor R CrB closely and inform us of its behavior.

REVISED FINDER CHARTS FOR 1908+01 NOVA AQUILAE 1993 
AND 1911-00 FO AQUELAE

Accompanying are revised b and d scale AAVSO charts for 1908+01 Nova Aql 1993. On 
the b scale chart (which has the main header of 1911-00 FO Aquilae), the position of the 
10.6 star to the southeast of the nova has been revised. On the d scale chart, the position of 
the 13.7 star northeast of the nova has been corrected, and a 13.2 star has been added. 
Please check your observations of N Aql 93 and revise them if they are affected by these 
corrections (particularly the correction of the 13.2 and 13.7 stars), and resubmit to 
Headquarters any revised observations. We apologize for the errors on the previous 
charts, which were distributed with AAVSO Alert Notice 173. We thank C. Scovil for his 
efforts in preparing and/or correcting these charts.

Also accompanying is an f scale AAVSO chart of N Aql 1993. N Aql 93 at this time is 
around magnitude 13.3, as reported by D. York and G. Poyner. If possible, please monitor 
this nova as it continues to fade.

EUVE OBSERVATIONS OF 2138+43 SS CYGNI DURING ITS 
RECENT OUTBURST

Thanks to the immediate notification by our observers of the outburst of SS Cygni that 
started on August 15, we notified the astronomers who had the observing run with the 
EUVE. The EUVE observations of SS Cyg started 8 hours after our alert! The satellite 
observed SS Cyg for 200,000 seconds(!!) during its slow rise to maximum and at maximum, 
and obtained unprecedented EUVE data for this anomalous outburst.

The astronomers involved in this research extend their appreciation and sincere thanks to 
all the observers who monitored SS Cyg closely and notified Headquarters of its outburst 
and behavior throughout the outburst. Your daily updates and valuable observations made it 
possible to have this unique and long target of opportunity observing of SS Cyg.

REMINDERS

Please continue to monitor 2023+43 V503 Cyg, and inform us of its behavior (see AAVSO 
Alert Notice 173 and 174).

Please continue to monitor 0409-71 VW Hyi and 2138+43 SS Cyg throughout the rest of 
1993, and inform us of their outbursts (see AA VSO Alert Notice 173 and 174).

Please keep us informed of the brightness and behavior of 1813+49 AM Her (see AAVSO 
Alert Notice 173 and 174).

Also continue to monitor V348 Sgr, and inform us when it becomes brighter tlaark 
magnitude 13.5 (see AA VSO Alert Notice 173 and 174).

Our thanks, together with those from the astronomers observing cataclysmic variables with 
ORFEUS, EUVE, HST, and ME, go to you, our observers for your close monitorings and 
notifications to Headquarters. Your observations definitely make a difference, and help in 
the success of observing runs of these stars with NASA's space satellites.

Clear skies, and good observing!

Janet A. Mattei 
Director

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