Presentation on theme: "Double Stars Discovered by IOTA and Reported to JDSO (Journal of Double Star Observations) (or in process to be reported) Tony George Presented at IOTA."— Presentation transcript:
Double Stars Discovered by IOTA and Reported to JDSO (Journal of Double Star Observations) (or in process to be reported) Tony George Presented at IOTA 2011 Conference – Rocklin, CA
JDSO Reports Submitted January 2010 – July 2011 Summary Table JDSO Publish Date Event DateAsteroid (No) Name Target StarSeparation (mas) PA Vol. 6 No. 2 April 1, 2010 2009 November 18 (1048) Feodosia TYC 4677-00696-1NA Vol. 7 No. 2 April 1, 2011 2010 October 20 (675) Ludmilla UCAC2 4116861328.3 ± 2.0205.1 ± 3.5 Vol. 7 No. 3 July 1, 2011 2009 July 19 (790) Pretoria TYC 2255-01354-1144.8 ± 0.4192.4 ± 0.2 Vol. 7 No. 3 July 1, 2011 2011 January 24 (160) Una HIP 462496.5 ± 1.150.2 ± 12.2
2009 November 18 (1048) Feodosia occults TYC 4677-00696-1 Alan Whitman This was an outstanding example of how a visual observer can detect a double star with careful observation and recording of their observation notes. Here is the actual report excerpt: At 04:28:01.0 the magnitude 10.1 target star TYC 4677-00696-1 crisply faded but did NOT disappear. It remained at least as bright as magnitude 12.9 GSC 4677-806 located 1.7' northeast. This failure to dim the predicted 4.7 magnitudes completely surprised me and resulted in a very long reaction time that I estimated to be 0.75 seconds. (This estimate is on the tape, a couple of minutes after the event.) I.. (made).. a conscious effort to compare the magnitudes of the two stars during the brief occultation.] Transparency was excellent and the seeing was fair since the 1.8 double star Alpha Psc was only occasionally split at 366x. Nevertheless, the stars looked crisp at the ultra low power used to monitor the asteroid occultation. I observed the asteroid 54 minutes after the event, when it had moved 18 away from the target star, and the asteroid was barely visible with direct vision at 366x. So the asteroid was as faint as it should be. The asteroid could not have been seen with the ultra low power of only 45x used during the occultation. Therefore the object which was at least magnitude 12.9 during the asteroid occultation must have been a companion star.
2010 October 20 (675) Ludmilla occults UCAC2 41168613 Kerry Coughlin and Roc Fleishman This is an excellent example of an ABBA combined with a BB event:
2009 July 19 (790) Pretoria occults TYC 2255-01354-1 Bill Cooke, Scott Degenhardt, David W. Dunham, Steve Messner, Robert Suggs, Roger Venable, Wayne H. Warren, Jr This is an excellent example of an AABB event:
2011 January 24 (160) Una occults HIP 46249 Tom Beard, Ted Blank, Ron Dantowitz, Jack Davis, Dennis di Cicco, David W. Dunham, Mike Hill, Aaron Sliski, Red Sumner This is another excellent example of an ABBA event, with very unequal star magnitudes. Also Brad Timerson did an excellent fit to a Durech model:
Reports Currently in Progress JDSO Publish Date Event DateAsteroid (No) Name Target StarSeparation (mas) PA NA2009 April 16 (336) Lacadiera 3UC197-1153757.5 ± 0.7124.9 ± 5.2 NA2010 August 31 (695) Bella TYC 2322-01054- 1 1.2 ± 0.4188.7 ±29.9
2009 April 16 (336) Lacadiera occults 3UC197-115375 Carl Bracken, Doug Slauson, Al Carcich, John Centala, Bob Modic, Bob Cadmus The Lacadiera event found a fourth component of a previously known triple star system, making it a quadruple star system. This is an example of an ABAB event with very unequal star magnitudes. This report is still in progress.
2010 August 31 (695) Bella occults TYC 2332-01054-1 T Beard, David Dunham, Paul Maley, Walt Morgan, R Stanton The Bella event found a component so close to the primary star that the secondary occultation was barely detectable. This is an example of an ABAB even with very unequal star magnitudes. This report is still in progress.
Conclusions 1. Occultations are an excellent method of finding or verifying double stars. Any time a light curve is obtained from a video record, it should be carefully examined for the presence of step events that could be due to duplicity of the target star. Step events should be noted in the occultation report. Questionable results should be brought to the attention of the appropriate regional coordinator and submitted for independent review. 2. Visual observers should prepare in advance for the potential likelihood of duplicity and watch for anomalous dimming or step events. Report these events as carefully and completely as you can.