Recent Occultations by Deimos
and Ixion
William H. Hanna
Alice Springs, NT Australia
IOTA 32nd Annual Meeting 13 July 2014
College Park, MD USA
Topics
• June was a very good month for firsts
– Observed an occultation by (II) Deimos
– Observed an occultation by (28978) Ixion
• Current setup
• Historical results
The Deimos prediction came just in time
• I normally use Occult Watcher for long-term planning, but…
• John Broughton, a prolific occultation observer based in
Queensland, was examining upcoming predictions made by
Occult 4 and found that a narrow (~12 km) predicted path for
(II) Deimos, not currently listed in an OW feed, would pass just
to the south of Alice Springs.
• John sent me an e-mail (giving barely four hours notice) and I
immediately set up under ideal observing conditions.
• Observed a 1.5-second (of a possible 1.8-sec) occultation.
• The accuracy of the prediction was no doubt due in large part
to the fact that the target star was in the Hipparcos catalog.
The Deimos Prediction
The result (at 30 fps)
Short video of the Deimos occultation
(note that Mars is greatly overexposed)
<insert/play Deimos video here>
Ixion prediction
Credits: Rio Team & B. Sicardy
Dim target star
Gone
The result (at 3 sec. per frame)
The target star was a double
Credit: Jose-Luis Ortiz
Post-observation updated prediction
My current setup
• 8” Meade LX90 f/10 with a Meade f/3.3 focal
reducer at prime focus; polar mount
– Occasionally use a 14” Meade LX-200 GPS
• Point Grey Research Grasshopper EX GX-FW-28S5M
– Sony ICX674 2/3” 1920x1440 14-bit CCD
• Astronomical Digital Video System
(I am a beta tester)
– ADV Recorder v1.5.71 under Ubuntu Linux 12.04 LTS
• Fujitsu Lifebook E752 Laptop (Linux / Windows 7)
– with an IEEE 1394b 800 Mbps FireWire ExpressCard
Recent observations are from my balcony…
…on a pier relocated from the hillside
Results of 135 attempts (as of 20140628)
• Observed an occultation: 11
• Observed a miss: 76
• No observation: 48
– Weather: 33
– Equipment problems: 4
– “Self-induced”: 11
•
•
•
•
•
Target star too dim for my equipment: 4
Not set up in time: 3
Misidentified star field: 1
Software “feature”: 1
Personal reasons: 2
Positives
(52) Europa
(I) Charon
(134340) Pluto
20120704
20120727 (using a 14”)
20120826 (using a 14”)
(92) Undina 20130206
(790) Pretoria 20130320
(578) Happelia 20130506
(372)
(65)
(II)
(28978)
Palma
Cybele
Deimos
Ixion
20140217
20140422
20140617
20140624
(198) Ampella 20140625