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PLANETARY OCCULTATIONS: 2002 RESULTS


This page is intended to provide a brief summary of observational attempts for certain important events only. Full details of all events are published in the Section's Circulars.

(377) Campania - 2002 July 20
(96) Aegle - 2002 February 18
(754) Malabar - 2002 January 16

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Occultation of TAC -1305459 by (377) Campania - 2002 July 20:

SUMMARY:

A 9.5 second occultation was observed by Ross Dickie in Gore, NZ:

Observer's Name                  : Ross Dickie
Aperture (cm)                    : 20cm 
Focal length (cm)                : 200cm
Type (e.g. SCT; Newtonian)       : Schmidt-Cassegrain
Magnification                    : 133x
Observing site name              : Gore.
Longitude (East +ve)             : 168 55' 20.7"
Latitude (South -ve)             : -46 06' 22.7"
Height above Sea-level (metres)  : 81 metres.
Sky Transparency (Delete two)    : Good  
Star Image Stability (Delete two): Poor
Other Conditions:  
     (Wind, Clouds, Lights, etc.): Nor'westerly wind.
Time Source (e.g. WWV, VNG)      : WWVH-VNG5 MHz
Recording method (e.g. tape)     : Tape-recorder
Could you see the Asteroid?      : NO.
Approx. Limiting Magnitude       : 13.2
                                          | Estimated  |
                           Universal Time | Reaction   | Accuracy, Remarks
                              h  m  s     | Time (sec) | 
Started Observing          : 12:00:41
Disappearance At           : 12:03:36.4        1.7 second P.E. already subtracted.
Reappearance At            : 12:03:45.9        0.7 second P.E. already subtracted.
Stopped Observing          : 12:11:19

Was your reaction time (also known as Personal Equation) subtracted from 
any of the above timings?  : YES.
If YES, state value        : 1.7 second to the D. and 0.7 second to the R.

List all Interruptions to Observing: NONE. 

COMMENTS: 

I set up my C8 telescope on the vegetable garden to be in the shelter of the house in the 
nor'westerly gale.  The sky was mostly clear with a few high clouds, although none of them were a 
threat to the Campania target star's area in the western sky.  The seeing conditions was less 
than fair.  The 12.4 magnitude target star was slightly difficult to see.  Nevertheless, a 
9.5 seconds' occultation did took place during Steve Preston's predicted time, which the central 
time of my observed occultation actually occurred just ONE second behind Steve Preston's updated 
time for my exact longitude ! 
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Occultation of TYC 7299-00684-1 by (96) Aegle - 2002 February 18:

SUMMARY:

This event was predicted by Edwin Goffin to cross the far southern parts of the South Island of New Zealand. To see the Goffin prediction, click
here. Steve Preston's update moved the path west to cross the northern parts of the South Island. Click here to see the updated path.

Brian Loader observing from Darfield on the South Island has reported a very brief occultation.

Brian Loader (Loa), Darfield, New Zealand:

Brian reports: "Very short, blink like event, estimate it lasted no more than 1 second. The magnitude change was about 2.1: certanily a faint image remained. By the time I reacted and was pressing the button, the image was back to full brightness."

Disappearance At : 16:42:01.0 UT (PE of 1 sec applied)
Duration = Around 1 second
Monitored Period : 16:36:30 - 16:52 UT.

DISCUSSION:

Congratulations to Brian on his successful observation. As Brian noted further in his report: " Assuming a spherical object diameter 169 km, a 1 second duration would suggest I was something of the order of 250 m inside the shadow path. This would be equivalent to a shift to the south west of about 0.2 diameter or about 0.02 arc seconds compared to the update path. The event was about 4 seconds earlier, or something like 0.03 arc seconds." The era of sub-pathwide accuracy updates has certainly arrived.

Click here to see a plot of the updated path showing Brians location. Apart from a cloud foiled attempt from Wellington, no other reports have been recieved. As of 22 January 2002, no previous occultations involving (96) Aegle have been reported.

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Occultation of HIP 57132 by (754) Malabar - 2002 January 16:

SUMMARY:

This event was predicted by Edwin Goffin to cross the North Island of New Zealand covering the country around Auckland, Hamilton and the Bay of Plenty. To see the Goffin prediction, click
here. Steve Preston's update moved the path slightly north centreing it on the Auckland metropolitan area. Click here to see the updated path.

While the target star was at the uncomfortably low altitude of 16 degrees at the time of appulse, frustrating some observers with light pollution within Auckland, the stars brightness and reasonably cooperative weather at the time made this a good prospect for a large number of potential observers. Unfortunately, only two actual observation attempts have been reported. Diana Watson (Wad) observing from Whakatane almost one path width to the south of the update path's southern limit saw no occultation. David and Stephen Clark monitored the event from central Auckland and have reported a positive observation.

David and Stephen Clark (Cld/Cls), Auckland, New Zealand:

David and Stephen Clark report: " Sorry about the poor data quality, but it was our first occultation observation. We foolishly chose to have one observer notice the 'off' and then to swap observers in my small (6") scope to watch the 'on' event. Unfortunately, by the time we had swapped observers, the occultation had ended :( However we learnt a lot, and are keen to do much better next time!

Disappearance At : 11:11:41 UT (PE of 2 sec NOT applied)
Reappearance No Later Than : 11:11:50 UT
Duration = less than 11 seconds
Monitored Period : 11:09 - 11:16 UT.

Diana Watson (Wad), Whakatane, New Zealand:

Monitored Period - 11:05 - 11:21 UT.
No occultations observed.

DISCUSSION:

Congratulations to David and Stephen on their positive observation. Close inspection shows that the Clarks observed from very close to the centreline of the updated path. Despite the shortcomings of their observation, it is quite clear that the chord observed by the Clarks was near the limb of the asteroid instead of central as predicted by the update as the maximum possible duration of their observation (11 seconds) is well less than the expected maximum of 24.9 seconds. Their observation was also around 20 seconds earlier than preidcted by the update.

Click here to see a diagram showing the relative positions of the Clarks observed chord and Diana Watson's location. In this diagram, the Clarks chord has arbitarily been placed on the northern limit to show that Diana's observation does not preclude this possibility. It is obvious that, at its expected size of 90km, without further observation reports from the Auckland area, it will be impossible to tell if the Clarks chord is actually the northern or southern edge.

As of May 2001, no previous occultations involving (754) Malabar have been reported.

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