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PLANETARY OCCULTATIONS: 1999 RESULTS


This page provides a brief summary of observational attempts for the following important 1999 events. Full details were published in the Section's Circulars.

(194) Prokne - 1999 November 2
(444) Gyptis - 1999 March 26
(524) Fidelio - 1999 March 19

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Occultation of TYC 5303 00317 by (194) Prokne - 1999 November 2:

SUMMARY:

Cloud! Rain! You name it, but anything except clear sky in the potential region of visibility...

Graham Blow, Wellington, NZ:
Rain.

Brian Loader, Christchurch, NZ:
Clouded out.

Malcolm Macdonald, Rotorua, NZ:
Sky completely overcast.

Rod Austin, New Plymouth, NZ:
Well I came, I tried to see, but the cloud conquered once again. A think sheet of cirrostratus swept in and got so thick that by 1 am Jupiter was only barely visible.

Diana Watson, Whakatane, NZ:
194 Prokne 1999 Nov.2.--no luck, thick cloud cover and some rain.

Doug Inwood, Christchurch, NZ:
The night of the second was clouded out here with virtual total cover. Maybe better luck with the next, or next, or next.....

Gordon Hudson, Pukerua Bay, NZ:
We were going to attempt this event last night but unfortunately it was raining here and we saw nothing.

Bob Evans, Invercargill, NZ:
1 hours before the Prokne occultation it was still 100% thick overcast clouds as it had been all evening so I opted for my beauty sleep.

Jack O'Kane, Upper Hutt, NZ:
I was prepared to have a go at this event. Upper Hutt was clouded over.

Noel Munford, Palmerston North, NZ:
Just a note to let you know that we were clouded out the other night and at no time had a chance to observe anything. Its worth recording though that I did have seven observers willing to participate which indicates a degree of interest. I think this came about from the local appreciation of my success last time.

Alan Thomas, Alexandra, NZ:
Well it was a perfect night for observing the occultation from Alex except for two problems.....I was only using 10x50 binoculars and could only just make out the 9th mag star. More basic, my internal alarm went off at 0130! However, with binoculars I was right on the edge and I doubt if I could have accurately timed the event.

Albert Brakel, Canberra, Australia:
I monitored the Prokne appulse last night, and saw both star and asteroid.The images merged at about 11:58 UT. At about 12:14 I thought I saw them resolved again during fleeting moments of clarity, and they had definitely separated by 12:15. The seeing after separation was not as good as before merging. While merged, there was no drop in magnitude to indicate that anoccultation had taken place.

Stephen Kerr, Rockhampton, Australia:
Monitored 11:55 - 12:09, the latter few minutes through light cloud. No occultation seen.


Occultation of TYC 0723 00457 by (444) Gyptis - 1999 March 26:

SUMMARY:

A definite occultation and two possible occultations by Gyptis have been reported by three observers in southeastern Australia; however many observers were hampered by cloud.

Rob Purvinskis, Stockport, SA:
There's good news and bad news.
1. I successfully observed a 6 second event at Stockport last night, with the 15" dobsonian telescope in a clear moonlit sky!
2. My tape was running but not recording, I lost track of the WWV tones, and hence can only estimate the time to the nearest 20 seconds - about 10:40:30!
3. Our telescope computer power supply blew up, preventing us from imaging the star and asteroid for astrometry postdiction.
ARGH!
Anyway, some data is better than no data! This is my first successful observation after more than 10 years of attempting occultations!

Ian Porter, Rye, Vic:
[20 cm Newtonian at 100 x; Transparency and Seeing good; Telstra time signal + tape recorder]
Started Observing : 10 35 30
Disappearance At : 10 41 16.12
Reappearance At : 10 41 17.63
Stopped Observing : 10 46 00
Event Duration : 1.4 seconds
ADDITIONAL COMMENTS: I saw a possible disappearance of the star as detailed above, but I do not have a high level of confidence in the observation. The star was close enough to the limiting magnitude to be jumping up and down in perceived magnitude and it is quite possible that is what I saw.

Alfred Kruijshoop, Mt Waverley, Vic:
Started Observing : 10:20:30
Disappearance At : 10:37:55.2 est. acc. 0.3 sec
Reappearance At : 10:37:57.0 est. acc. 0.3 sec
Stopped Observing : 10:50
Event Duration : 1.8 seconds
ADDITIONAL COMMENTS: This was a difficult observation, with a fairly faint star and bright 70% moon making every bit of haze or cloud very obvious. However, my record of the 1.8 sec event and my recollection are very clear and positive....

...there were many tens of breaks due to cloud and these continued across the important period around 10:40.6. My complete tape is available and I can carefully analyse sections of it, at the times when other observers may have seen something. Because my observation was earlier than predicted we should be a bit skeptical. But when making the observation I instinctively and immediately said very definite: "Gone" and not something vague about clouds rolling in. I am fairly sure that on this occasion the star disappeared "POP" in a dark cloudless sky. The fact that I firmly stated "Gone" was based on my occultation timing experience. At that moment I was convinced that this was a typical instantaneous disappearance and my trained reflexes said so. Of course we always do have the risk of moving the head so the eye moves out of the exit pupil. But as I was using very familiar equipment (scope and 17 mm eyepiece) I do not think my head would have swayed so far to lose the star without me noticing this and stating this on tape..

David Shead/Bob Parsons, Pakenham, Vic
At the predicted event time, a long but narrow band of cloud had approached from the west and was elongated in an east/west orientation.The cloud was initially patchy enough to keep observing, however it was causing some interference. This was my first attempt at an occultation, for which I nominated Bob Parsons as my time keeper and tape operator. I believe I had identified the target star, and was positive of the position of the approximately magnitude 5 and 8 guide stars closest to it. Due to my limited skills and the cloud interferance I would suggest the credibility of my results to be questionable. Reviewing the tape I had reported a flicker at the target star atapproximately 10:39:49 (UT). Then at approximately 10:40:16 seconds I stated on the tape the following indecisive comments: "Going...Going....Gone....No Still There...Very Faint. This event ended at approximately 10:40:18.25. As stated above I am unsure of my observation particularly due to the cloud. I was observing with an 8 inch Dobsonian from my home in Pakenham. My position as per my G.P.S is Latitude 38d03m52s Longitude 145d29m09s.

Joe Grida, Adelaide, SA
You've already received a report from Rob Purvinskis regarding this occultation. I'm still collating data, but can report that as at Sunday 28/3, two more positive results have been received. Both correlate with what Rob has already reported. As soon as I can, I'll pass on the other details to you. I had 16 obsevers participating. I hope to get more reports in the next few days.

...When I eventually did get home, 10 minutes before the event was due to start, high cirrus cloud in the west would have prevented me from seeing anything anyway.

Peter Skilton, Cape Schanck Lighthouse, Vic:
Not quite all doom and gloom, but no reported positives from our neck of the woods, though over 20 of our society's observers have not contacted me yet - some definitely were going to try the event regardless of weather, others may or may not have attempted the event. Absence of reports strongly suggests they saw nothing. Weather cleared up a bit in the evening, but it is remotely possible the shadow passed us during cloud cover. Cloud interference was worse the further north the site was (the reverse of last minute weather bureau predictions for event time).

[At Cape Schanck lighthouse]: Multiple intermittent minor cloud interference, so have not listened back to tape yet. No definite disapps, though I do remember an early fade which I thought was nothing more than due to cloud. Star was quite faint, probably a contrast effect due to moonlight.

Peter Lowe, Langwarrin, Vic:
[Reported by Peter Skilton]: I had clear skies but I should have checked my horizon before hand because the star was behind the only "black" spot from my observatory: a tree to the north. It's never really been a problem before because I can view objects before they move into that part of my skies.

Renato Alessio, Noble Park, Vic:
[Reported by Peter Skilton]: Eagerly anticipating Gyptis, I had clear sky for an hour and a half leading up to 1025. Then, around 30secs into my watch it got cloudy. Then that cloud nearly cleared, when what looked like a river of laminar flow sky particles (emanating from the gas works in Dandenong, I think) was smack bang over where Gyptis was supposed to be. I couldn't believe it - clear skies either side of this stream. The stream only moved when cloud pushed it away. Anyhow, the sky was perfectly clear three quarters of an hour later, when it was time for Mars observation.

John Cleverdon, Dromana, Vic:
[Reported by Peter Skilton]: I watched the star from 1039 to 1043; however, during that time, there was no dimming of the star. At the same time though, there were patches of cloud crossing the field of view, so it was obscured at times. After 1043, it became too cloudy to do any more viewing.

Bruce Tregaskis, Mt. Martha summit, Vic:
[Reported by Peter Skilton]: Cloud interferences, no definite disapps. He will take some time to analyse his tape due to complexity.

Peter Hyson, (possibly Seaford, Vic):
[Reported by Peter Skilton]: My 4" was not completed in time, but I tried with 12x50 binoculars. Under optimal conditions I might have made it, but with the bright moon and the occasional cirrus floating across, I never saw the target star.

Richard Pollard, Dandenong, Vic:
[Reported by Peter Skilton]: Regrettably, even with the best of intentions I was unable to image the star. Not enough aperture, I'm afraid. I had the area alright, but couldonly see down to about 9.5, thanks to the moon and a bit of pollution fromwhat used to be ACI Fibreglass.

Jim Blanksby, Wandin, Vic:
[Reported by Peter Skilton]: Very considerable cloud interference, no disappearances, will report to you separately.

Martin George, Launceston, Tas:
Here is my negative observation of the Gyptis event from Mar 26.

Martin Harvey, Launceston, Tas:
[Reported by Martin George]:
Started Observing : 10:28:00
Stopped Observing : 10:49:00
Seeing was a little unstable from about 10:38:00 to 10:39:30.
No occultation seen.

Dave Girling, Mornington, Vic:
Observed 10:30:00 - 10:46:00.
Breaks for cloud between:
10:32:50 - 10:33:05
10:36:08 - 10:36:55
10:37:40 - 10:38:10
10:39:00 - 10:39:45
10:40:58 - 10:41:09
10:42:10 - 10:42:50
10:43:00 - 10:46:00

Albert Brakel, Canberra, ACT:
An hour before the event, patchy and thin cloud covered the sky except for the SE. I set up my equipment, but after a while it became obvious that the cloud was thickening. The SE was still clear, so I made a snap decision to pack the car and drive that way, to near the airport. I got there 16 minutes before the event was due, but it was no use. The clouds had covered even that part of the sky in the meantime, so I was faced with a total blockout. John Morland was unable to observe, with 95% cloud cover.

Vello Tabur, Canberra, ACT:
It was totally cloudy...

Col Bembrick, Bathurst, NSW:
I'm thinking of writing a paper on the intelligence of clouds. They seem to know to the nearest hour - sometimes even to the nearest minute - when there is a minor planet occn or Jupiter satellite event, or other time-critical astronomical event. I'm sure I could lash up a graph with a correlation coefficient close to 1.0 for the percentage of clouds vs the importance of the astronomical event of the day.

You guessed it - the 444 Gyptis event was clouded out here in Bathurst. All day there were clear blue skies, but by sunset it had started to cloud over and by the time of the event it was starting to rain. My only consolation is that it DID rain - we still need some for 1999. So often it seems to cloud over and doesnt rain - then I get mad.

Grant Murphy, Sydney, NSW:
G'day Graham. Friday was a nice clear and sunny day in Sydney. Obviously this meant that the evening was completely cloudy from just before sunset. Sorry.

Charlie Smith, Woodridge, Qld:
Caught glimpses of what I took to be the asteroid, but it was at the absolute limit of observation, and I was unable to make any estimations of distance etc. The star was clearly seen at all times, no events were observed.

Stephen Kerr, Rockhampton, Qld:
Started Observing : 10:35:00.0
Stopped Observing : 10:52:00.0
No occultation observed.

Brian Loader, Christchurch, NZ:
No observation possible from Christchurch. Identified field OK about 15 minutes before event, ie at about 10:28 UT. However at ca 6 degrees the extinction was too great and seeing too poor to be able to see the 10.5 magnitude star. Air glow and moonlight probably no help as well. Did *not* attempt to observe through time of event - seemed no point as star not visible anyway!


Occultation of TAU LIBRAE by (524) Fidelio - 1999 March 19:

SUMMARY:
No event was seen from New Zealand, which is in accordance with the results of the "last-minute" pre-event update astrometry.

Bob Evans, Waikaia, northern Southland, NZ:
Well, it was actually clear for the Fidelio occultation! I observed no occultation while observing from 14h 35m 05s to 14h 57m 00s UT except for about a 3 second interruption around about 14h 45m 30s when I was distracted by a meteor of about -10 magnitude. It lit the place up! I was observing from Waikaia, northern Southland, approximate coordinates 168 51' east, 45 43.5' south.

Reg Sutherland, Tapanui, West Otago, NZ:
Clear night but no occultation.

Robin Gledhill, Dunedin, NZ:
Saturday morning here was very cloudy. So much so that I had difficulty identifying Scorpio, and could not identify Libra. The clouds had a few breaks and they were travelling quite fast, eastwards.

Catherine Cross/Bruce Thompson, Oamaru, NZ:
Monitored 14:30-15:00; No occultation.

Doug Inwood, West Melton, Canterbury, NZ:
We saw nothing.... Had perfect observing conditions and no trace of cloud throughout. We started observing at 14:40 to 14:55 UT and saw no change in Tau Libra. I was on the 14, Orlon with his 4, Carol with the binocks and Milan with his 6 inch. We had a time signal in the end - but we suffer lack of aerial or something - reception wasn't great.

Clive Rowe, Waddington, Canterbury, NZ:
Lovely clear,warm night out here. Watched tau Libra from 3:40 am to 04:00 am [NZDT] and saw no dips at all. Excellent conditions.

Larry Field, Birdlings Flat, Canterbury, NZ:
[No occultation].

Brian Loader, Parklands, Christchurch, NZ:
[14:40 - 14:55 UT]. No event observed.
Break 1: 14:40:00 - 14:40:50 : Cloud (just vis for a second or two about 14:40:40)
Break 2: 14:45:30 - 14:45:35 : (5 sec) cloud
Break 3: 14:47:12 - 14:47:15 : (3 sec) cloud
Break 4: 14:50:54 - 14:50:56 : (2 sec) cloud When clear, transparency was excellent. However apart from the above there were a number of spells when star faded, at times being at limit of visibility. The above times were the only ones where it was completely lost to view. I am certain there was no event outside the breaks indicated. These latter were definitely all fades due to cloud. For the start I had decided to formally start viewing at 14:40, although I monitored most of the previous minute. The star faded a few seconds before 14:40 and disappeared from view at 14:40:00 to the nearest second! However it was back in view by 14:40:50.

Jack O'Kane, Wellington, NZ:
[14:33 - 14:53 UT]. Observing conditions were very good. Star did not disappear.

Ed Budding, Tawa, Wellington, NZ:
I "had a go" with the Fidelio event last night. Perhaps I did something wrong -- but the observing conditions were good in Tawa. I did not see any occultation of the star that I believe was tau Librae over the interval 3h 32 to 3h 52 NZDST.

Don Glass/Joe Triebels, Hawera, NZ:
Cloudy all night.

John Harper, Napier, NZ:
Was in Napier 39deg 30min S 165deg 55min E looking at tau Lib on 1999 Mar 19 UT 1430 to 1455 hrs. Timing by WWVH. Naked eye: 5th mag star nearby just visible. 2 observers (JF Harper, MA Harper) agreed: no occultation seen.

Malcolm Macdonald, Rotorua, NZ:
[14:20 - 15:oo UT]. Conditions were excellent. Observed continuously without breaks or distractions. No occultation was observed by me.

Diana Watson, Whakatane, NZ:
No positive result, will send written report in due course.

Dennis Goodman, Auckland, NZ:
Typically, Murphy ruled here for the Saturday morning event. Fine early evening, then it clagged up and stayed that way all night. Cloudy during the day, and cleared just after the Moon Saturn and Venus set!

David Neil, Whangarei, NZ:
Bad news about the occultation. I have no result for you.

Peter Skilton, Victoria, Australia:
- I was clouded out at my usual site.
- Bruce Tregaskis in Mt.Eliza reports by phone that he monitored from 1:35-1:48:30 local daylight savings time, using 10x50 binoculars, and saw no disappearance. He had to contend with thin cloud throughout, but is an extremely experienced observer.


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