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 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 AAVSO 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 AAVSO 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 AAVSO 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 AAVSO 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!
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