CHORDS TO DATE: 3

Chord 1: Alan Gilmore, Mt John, NZ (Photoelectric)
Chord 2: Brian Loader, Darfield, NZ
Chord 3: Euan Mason, West Melton, NZ

OBSERVATIONS AS REPORTED BY THE OBSERVERS:

Observer's Name                  : Alan Gilmore
Aperture (cm)                    : 60
Focal length (cm)                : 960
Type (e.g. SCT; Newtonian)       : Cassegrain
Magnification                    : N/A  (photometer at Cassegrain focus)
Observing site name              : Mt John Observatory
Longitude (East +ve)             : +170d 27.9'
Latitude (South -ve)             : -43d 59.2'
Height above Sealevel (metres)   : 1020
Time Source (e.g. WWV, VNG)      : See notes
Recording method (e.g. tape)     : Photometer computer
Could you see the Asteroid?      : ?
Approx. Limiting Magnitude       : ?
                                          | Estimated  |
                           Universal Time | Reaction   | Accuracy, Remarks
                              h  m  s     | Time (sec) | 
Disappearance At           : 12:08:44.6
Reappearance At            : 12:08:55.0
Duration                   : 10.4 sec

ADDITIONAL COMMENTS: Pam and I got the (259) Aletheia occultation in marginal conditions (some 
cloud, poor seeing) with the single channel photometer on the 0.6 m 'OC'  telescope at the 
University of Canterbury's Mt John Observatory. The measures were made with a Cousins R filter 
and 47" aperture. In 100ms integrations the counts dropped from ~730 to ~260 counts during the 
occultation. 

Problem (again!) with absolute time: With me flashing a torch into the telescope in time to Pam 
calling the GPS times (_assumed_ to be exactly 2s slow) the computer clock appears to be off 
by 0.5 second.  Due to my not noting a 10th second in the flashes, I don't know whether it was 0.5s 
fast or 0.5s slow! Again WWVH reception was too poor for an independent check.

Observer's Name                  : Brian Loader
Aperture (cm)                    : 25.4
Focal length (cm)                : 250
Type (e.g. SCT; Newtonian)       : SCT
Magnification                    : --- Video Observation
Observing site name              : Darfield
Longitude (DD MM SS ; East +ve)  : +172° 06' 24.4" E
Latitude (DD MM SS ; South -ve)  :  -43° 28' 52.9" S
Height above Sealevel (metres)   : 210
Geodetic Datum (e.g.WGS84,NZ1949): WGS84
Height Datum (if known)          : MSL?
Sky Transparency (Delete two)    : Good?  see comments
Star Image Stability (Delete two): Poor
Time Source (e.g. WWVH, GPS)     : GPS/KIWI
Recording method (e.g. tape)     : Video tape with LED flash each UT second
Could you see the Asteroid?      : No
Approx. Limiting Magnitude       : 11 on the video.
                                          | Estimated  |
                           Universal Time | Reaction   | Accuracy, Remarks
                              h  m  s     | Time (sec) | 
Started Observing          : 11:50
Disappearance At           : 12:08:47.7  Reaction time n/a   ± 0.5 second
Star and Object Separated  : 12:08:57.0  Reaction time n/a   ± 0.2 second 
Stopped Observing          : 12:10
Duration                   : 9.3 sec

ADDITIONAL COMMENTS: An occultation certainly occurred.  It is impossible to get really precise 
times from the videotape due to seeing and, presumably, extinction due to lowering altitude, 
making the image barely discernable.  The times given would have to be given a certainty 
rating "2", that is "could be spurious", due to the very poor image.

The star image was just about reasonable half an hour before the event, but deteriorated as 
the star got lower.  Since Clive Rowe, observing about 11 km to the west, saw the star fade 
from view about 3 minutes before the event, due to cloud, it is possible that sky transparency 
was getting poorer without my realising it.

Observer's Name                  : Euan Mason
I got a good observation from the R.F. Joyce Observatory using my 8 inch F6 Newtonian at 170x.:

12:8:48.0 UT off
12:8:59.9 UT on
Duration: 11.9 sec

There was a "winking" sequence of off:on:off lasting perhaps 0.2 sec at the beginning, and exactly 
the same time for on:off:on at the end.  I can't think of an explanation for this, but it was very 
clear.  Can anyone else explain it?

Ashley Pennell (Dunedin): Cloud

Paul Rodmell (Invercargill):
Lovely evening, collimated, polar aligned, found star OK, set up recorder radio, etc.  
Nice star until about 11:45 when it started fading.  Then couldn't see the brighter stars 
pointing to the star, then by about 12:00  couldn't see anything out to the south-west.  Gave 
up at 12:09.  Went out about 12:30 and the patch of high level cloud seemed to be to the south 
and it was clear to the south-west.

Graham Blow (Martinborough):
I drove to a site near Martinborough in the Wairarapa. The sky was largely clear of 
clouds – excpet in the west around the region of the star. Cloud drifting over the field 
hampered my identification of the star although I believe I did acquire the correct star just 
before the occultation time.  However even in a C8 it was only visible occasionally using 
averted vision and it was therefore not possible to unambiguously identify any occultation 
compared to the random coming and going of the image. 

Clive Rowe (Waddington) - about 11 km west of Brian Loader:
The star faded from view about 3 seconds before the expected time of event.  

Alan Thomas (Alexandra):
Intermittent cloud or fog at Alexandra.  

Stu Parker (Wyndham) - near Invercargill:
Sorry I didnt record a event from here in southland.The seeing was really poor. 
The star was hard to see. There was also a little haze low on the horzion.

Owen Moore (Wellington):
Cloud rolled in about 10 minutes before the event.

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