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Alert Notice 176: Fourth update on ORFEUS mission AND Fading of R CrB AND Revised finder charts for Nova Aql 1993 [V1419 Aql] and FO Aql AND EUVE observations of SS Cyg during its recent outburst AND Reminders

THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
25 Birch Street, Cambridge, MA 02138 USA
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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 AAVSO 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 [V1419 AQl] AND 1911-00 FO AQUILAE

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 AAVSO Alert Notices 173 and 174).

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

Also continue to monitor V348 Sgr, and inform us when it becomes brighter than magnitude 13.5 (see AAVSO Alert Notices 173 and 174).

Our thanks, together with those from the astronomers observing cataclysmic variables with ORFEUS, EUVE, HST, and IUE, 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!


Director

files: Nova Aql 1993 revised 'b' and 'd' scale charts; Nova Aql 1993 new 'f' scale chart

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