Transcript Summary of Double Star Discoveries and JDSO Submissions

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 Date
Asteroid
(No) Name
Target Star
Separation
(mas)
PA
Vol. 6 No. 2
April 1, 2010
2009
November 18
(1048)
Feodosia
TYC 4677-00696-1
NA
NA
Vol. 7 No. 2
April 1, 2011
2010
October 20
(675)
Ludmilla
UCAC2 41168613
28.3 ± 2.0
205.1
± 3.5
Vol. 7 No. 3
July 1, 2011
2009
July 19
(790)
Pretoria
TYC 2255-01354-1
144.8 ± 0.4
192.4
± 0.2
Vol. 7 No. 3
July 1, 2011
2011
January 24
(160)
Una
HIP 46249
6.5 ± 1.1
50.2
± 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 Date
Asteroid (No)
Name
Target Star
Separation
(mas)
PA
NA
2009
April 16
(336)
Lacadiera
3UC197-115375
7.5 ± 0.7
124.9
± 5.2
NA
2010
August 31
(695)
Bella
TYC 2322-010541
1.2 ± 0.4
188.7 ±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.
2.
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.
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.