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We report an attempted observation of
an occultation of UCAC star 26252549 by trans-Neptunian object Quaoar on May
1 2009. 15 observations were performed in 14 stations (see attached map),
with telescope diameters ranging between 1 m and 25 cm. 3 were clouded out, 2
were lost to pointing/timing, 10 acquisitions were negative. A brief summary
of observing reports is attached. The shadow was predicted to pass
slightly outside the Earth, although given the uncertainties involved, it
could have been potentially visible from Australia and New Zealand. Recently
updated prediction was derived from a reanalysis of the star position by the
Rio group of its 2008 observations, with an applied ephemeris offset for
Quaoar of 0.015 arcsec in RA and -0.175 arcsec in DEC. A stellar occultation
by Quaoar's satellite (distance of about 0.35 arcsec, with an estimated
diameter of 100 km) or any additional orbiting material, was not reported. We would like to take advantage of this
report to invite all observers involved to acquire post-event images of
Quaoar along with nearby UCAC stars and send them to our group, to improve
offset determination for future event predictions. J2000 stellar coordinates
: 17 18 12.5402 -15 24 49.845
-41 -29
-36.2 S Vintage Lane, New Zealand, Bill Allen, T60cm, 1-sec exp + T40cm,
2-sec exp. -173 -50
-20.72 E 37.5 m 00 00
00. no event 00 00
00. --------------------------- -33 -39
-52.0 S Hawkesbury Heights, Blue Mountains, NSW, Dave Gault, 25 cm Newt. -150 -38
-28.0 E 286. m 00 00
00. no event between 13:28 and 14:05 00 00
00. GPS - time inserted --------------------------- -32 -27
-21.3 S Mudgee, NSW, Steve and Jan Quirk, 31.5 cm Newt., 0.25-0.5 s -149 -39
-45.6 E 508. m 00 00
00. no event between 13:42:01 and 13:55:50 00 00
00. hazy cloud during obs --------------------------- -40 -51
-20.21 S Waikanae Beach, NZ, John Talbot, 25 cm, 0.25-0.5 s -175 -01
-57.31 E 5 m 00 00
00. missed target zone by 1 screen 20 arcmin 00 00
00. 13:30-13:50 deteriorating transparency --------------------------- -33 -55
-33.47 S Bankstown, Sydney, NSW, Ted Dobosz, 28 cm, 5 s -151 -01
-26.93 E 25 m 00 00
00. SBIG ST10XE 3x3 binning 00 00
00. no event between 13:30 and 14:00 --------------------------- -35 -25
-00 S Canberra, ACT, Dave Herald -149 -05
-00 E 500 m 00 00
00. no event between 13:35 and 14:05 00 00
00. --------------------------- -42 -50
-49.4 S Hobart Canopus obs.1-m telescope, Tasmania, John Greenhill -147 -25
-52.6 E 1000 m 00 00
00. no event between 13:10 and 13:50 00 00
00. --------------------------- -34 -19
-55.2 S Stockport, South Aust., Blair Lade, Tony Virgo, clouded out -138 -44
-4.0 E 200 m 00 00
00. clouded out till 15:00 00 00
00. --------------------------- -27 -28
-00. S Jonathan Bradshaw, Brisbane, QLD -153 -01
-30. E 100 m 00 00
00. no event 00 00
00. --------------------------- -27 -59
-25. S John Broughton, Gold Coast, Australia -153 -22
-7. E 200 m 00 00
00. (delayed) no event between 14:02:11 and 14:30:38 00 00
00. --------------------------- -17 -37
-00. Tahiti, Southern Stars Observatory, Roland Santallo, clouded out +149 +29
+00. 100 m 00 00
00. clouded out 00 00
00. --------------------------- -23 -22
-40 Rockampton, Queensland, Steve Kerr -150 -30
-50. E 100 m 00 00
00. negative 00 00
00. --------------------------- -20 -34
-21. Mount Isa Astronomy Group, Marc Katona, Len Fulham, 28 cm -139 -34
-01. E 370 m 00 00
00. Mallincam Hyper Plus CCD cam at prime focus 00 00
00. seeing Antoniadi II, transp. 9/10, no event 13:25-14:10 --------------------------- -43 -59
-5.1 S Mount John NZ 1-m telescope, Brian Loader, Alan Gilmore -170 -28
-49. E 720 m 00 00
00. Variable clouds thickened 25 min before time of event 00 00
00. clouded out --------------------------- |
