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The track of this occultation was predicted to cover the region between approximately Wellington and Wanganui, NZ. Occultation reports were received from Wanganui and Pukerua Bay, about 30 km north of Wellington, while an observer at Waikanae, between the two, did not report an event.
View the updated prediction.
Observers: 1 R. Skilton, Wanganui, NZ 2(M) J. Talbot, Waikanae, NZ 3 G. Hudson, Pukerua Bay, NZ M = Miss
The circle represents the predicted 60 km diameter of Patricia.
Discussion:
It is clear that not all reports received can be correct. In Wanganui, Ross Skilton was observing in a clear sky under good conditions. He was confident of his result, in spite of the fact that the star was mag 11.9 and this was the first occultation he has timed. His times are however consistent with Steve Preston's updated prediction.
In Waikanae, John Talbot was observing with only a 10 cm scope and noted that the star was right on the limit of visibility. He noted that if the star had disappeared he might well have not recorded the event, saying that he would not put higher than 50% confidence on his result.
In Pukerua Bay, Gordon Hudson was observing with a 30 cm scope but noted that the star was very difficult to see and appeared to fade in and out of visibility due to the seeing conditions. Further, Gordon's reported times, when reduced against the fundamental plane, are significantly offset from those expected should Ross Skilton's result be real.
Finally, while asteroids can sometimes have axes rather longer than their estimated diameters (which are derived from IRAS data), the length of one axis of Patricia would have to be at least twice the predicted size of the asteroid if the Wanganui and Pukerua Bay results are to be reconciled.
In summary, taking into account the comments of all the observers involved, it is most likely that the Wanganui result is real and the Pukerua Bay result spurious, with the Waikanae result being indeterminate.
Observational Data:
Observer's Name : Ross Skilton
Aperture (cm) : 20
Focal length (cm) : 203
Type (e.g. SCT; Newtonian) : SCT
Magnification : 12.5mm Plossl=162x
Observing site name : Tayforth, Wanganui
Longitude (DD MM SS ; East +ve) : 174 59 55 East
Latitude (DD MM SS ; South -ve) : -39 55 02 South
Height above Sealevel (metres) : 56 m
Geodetic Datum (e.g.WGS84,NZ1949): NZ1949
Height Datum (if known) : -
Sky Transparency (Delete two) : Good
Star Image Stability (Delete two): Good
Other Conditions : Gentle W breeze, Clear sky. No Moon, Dark site
Time Source (e.g. WWVH, GPS) : WWVH
Recording method (e.g. tape) : Tape
Could you see the Asteroid? : No
Approx. Limiting Magnitude : 13.5
| Estimated |
Universal Time | Reaction | Accuracy, Remarks
h m s | Time (sec) |
Started Observing : 06:31:00
Disappearance At : 06:34:40.1
Reappearance At : 06:34:43.8 Seemed good
Stopped Observing : 06:36:00
Was your reaction time (also known as Personal Equation) subtracted from
any of the above timings? : Yes
If YES, state value : 0.4s disappear /0.3s reappear
ADDITIONAL COMMENTS: First MP occ where I wasn't clouded out. Equipment performed well but
don't know reaction time. Average occultation time from tape is 5.43sec, agrees reasonably
with stopwatch at scope of 5.49sec.
Observer's Name : John Talbot
Aperture (cm) : 10cm
Focal length (cm) : 700cm
Type (e.g. SCT; Newtonian) : Newtonian, Saxon on Equatorial mount
Magnification : 28x (25mm eye piece)
Observing site name : 3 Hughes St, Waikanae Beach
Longitude (DD MM SS ; East +ve) : 175 01 56.6
Latitude (DD MM SS ; South -ve) : -40 51 19.1
Height above Sealevel (metres) : 5m
Geodetic Datum (e.g.WGS84,NZ1949): WGS84
Height Datum (if known) : MSL
Sky Transparency (Delete two) : Good
Star Image Stability (Delete two): Fair
Other Conditions: Strong wind 30kph+ , Cloud on East horizon but clear in target area,
some suburban lights
Time Source (e.g. WWVH, GPS) : WWV 10MHz
Recording method (e.g. tape) : Tape
Could you see the Asteroid? : no
Approx. Limiting Magnitude : ~11
| Estimated |
Universal Time | Reaction | Accuracy, Remarks
h m s | Time (sec) |
Started Observing : 6:15:00
Stopped Observing : 6:40:00
ADDITIONAL COMMENTS:
This was my first serious attempt at observing an occultation but in the event while I could just
make out the target star , I was not able to spot changes , I suspect due to lack of experience and
working right at limit of my scope and site. I will be trying again in the future.
Accuracy of this obs for null result: Well as I said it was my first real attempt so took me while to
get lined up. I am 90% sure I was looking at the right group of 3 faint stars with the target in
center. My scope and conditions were right at the limit as far as I am concerned. Target was quoted
as M 11.9 and I was only just able to separate it from background so it would have been easy to miss
the dip in brightness. Wind was strong so scope was shaking a bit but no so much I could not keep
stars in view - I did tuck in behind the fence to mimimise wind. I did lose concentration a couple
time but only for a second or two. Overall I would not put a high confidence on a null - certainly
not above 50%.
Observer's Name : Gordon Hudson
Aperture (cm) : 30cm
Focal length (cm) : 300cm
Type (e.g. SCT; Newtonian) : Cassegrain
Magnification : 120
Observing site name : Kotipu Place Observatory
Longitude (DD MM SS ; East +ve) : 174E 52' 54.36"
Latitude (DD MM SS ; South -ve) : 41S 02' 27.61"
Height above Sealevel (metres) : 108.5 metres
Geodetic Datum (e.g.WGS84,NZ1949): NZ1949
Height Datum (if known) : -
Sky Transparency (Delete two) : Average
Star Image Stability (Delete two): Fair
Other Conditions:
(Wind, Clouds, Lights, etc.):Clear & Gusty
Time Source (e.g. WWVH, GPS) : GPS
Recording method (e.g. tape) : Computer
Could you see the Asteroid? : No
Approx. Limiting Magnitude : 12
| Estimated |
Universal Time | Reaction | Accuracy,Remarks
h m s | Time (sec) |
Started Observing :6:20:00
Disappearance At :6:35:22 Spurious?
Reappearance At :6:35:28 Spurious?
Stopped Observing :6:45:00
ADDITIONAL COMMENTS: Star was very difficult to see and appeared to fade in and out of visibility
due to the seeing conditions.
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