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PLANETARY OCCULTATIONS: 2003 RESULTS


[Click here for results from previous years]

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.

(210) Isabella - 2003 April 21
(124) Alkeste - 2003 June 24
(709) Fringilla - 2003 June 28
(100) Hekate - 2003 July 14
(372) Palma - 2003 July 15
(976) Benjamina - 2003 July 19
(165) Loreley - 2003 July 20
(690) Wratislavia - 2003 July 24
(27) Euterpe - 2003 July 27
(205) Martha - 2003 August 06
(481) Emita - 2003 August 10
(21) Lutetia - 2003 August 24
(503) Evelyn - 2003 August 30
(230) Athamantis - 2003 September 01
(336) Lacadiera - 2003 September 18
(259) Aletheia - 2003 September 29
(219) Thusnelda - 2003 October 18
(99) Dike - 2003 October 20

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Occultation of TYC 6154-00401-1 by (210) Isabella - 2003 April 21:

This occultation was observed both photoelectrically by Alan Gilmore and Pam Kilmartin at Mt John (5.4 second chord), and visually by Robert Price at Bethanga (5.0 second occultation) and Patrick Purcell in northern NSW (2.4 sec event).

Alan Gilmore wrote:

Pam and I observered the (210) Isabella occultation at Mt John with the single channel photometer on the 0.6-m OC telescope. We used a 21" aperture and the Cousins R filter in moonlit sky. There was possibly some residual cloud near the region: some had formed but was dissipating. We ran 100 ms integrations from 10:10 till about half a minute after the occn. Pam saw the occultation in the 15-cm finder but didn't have facilities for timing.

We don't have an accurate absolute time of the occn. Due to radio aerial problems the WWVH signal was very weak. I could hear the minute tones but that was all. From the GPS display -- the one I discovered was 2 seconds slow at the last occn I observed -- I think the UT time is accurate to half a second; I might be able to refine it a little.

The most interesting part of the photometry was that the star didn't blink off and back on again. The list of integrations is appended. The star varies over a range of 1800-2000 counts till about10:16:00.5 computer time. At 00.6 it begins to fade but doesn't reach the sky limit till about 01.1. The rise begins at the end of the 10:16:05.1 integration then stays on a constant level, below full brightness, till just after the beginning of the 06.0 integration.

To be sure that this was not some previously unnoticed lag in the photometer we tried cutting the light path with the flip mirror while running the same integrations on the star. The drop and recovery were both 'instantaneous', i.e. within one integration.

The recovery is most easily explained by the presence of a faint companion star that appeared after the primary. The apparently linear -- though I haven't graphed it -- decline looks more like the effect of a coma.

Isabella Occultation Lightcurve

Robert Price reported:

Lat -36 deg 07 min 10.9 sec
Long 147 deg 05 min 22.8 sec
Altitude 350 m
Started Imaging with ST7 CCD camera: 9:20 UT
Disappearance at: 10:17:56.2 Visual x155
Reappearance at: 10:18:01.2 Visual x155
Personal Equation subtracted from the above times: Dis=0.5, Reap=0.4

Patrick Purcell reported:

Lat: -36 22 40.2
Long: 149 12 48.7"
Altitude: 858 m
Disappearance at 10:17:50.6
Reappearance at 10:17:53.0
Duration 2.4 seconds
Location: 20 km S of Cooma, NSW

Dave Herald, observing from not far away from Patrick Purcell, saw no occultation (which provides as limiting constraint on the size of the asteroid). The Mt John/Purcell and Price chords are on opposite sides of the asteroid, making it possible to fit an ellipse to the data.

Event analysis:

A preliminary analysis was carried out by David Herald, who found that he could obtain a reasonable fit to the data using an ellipse of 84.9 x 52.6 km - rather smaller than the 86 km diameter expected from the IRAS data. This is a significant result in itself, but the fact that occultations by both the primary and secondary components of the star were observed at Mt John has refined the orientation of Isabella's ellipse. In addition, from the photoelectric data Dave Herald has determined the components of the double star to be separated by 5.4 millarcsecond in a Position Angle of 81.9 degrees.

Even though the occultation by Isabella was observed from only three sites, the data has been sufficient to not only determine the approximately ellipsoidal shape of the asteroid and put good estimates on its major andan minor axes and orientation, but also to determine the separation and position angle of a previously undiscovered double star. An excellent result all round!

Plot prepared by David Herald :

1 = Herald; 2 = Mt John secondary; 3 = Mt John primary; 4 = Purcell; 5 = Price

Isabella Plot

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Occultation of beta Virginis by (124) Alkeste - 2003 June 24:

Please refer to the separate Alkeste results page here.

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Occultation of TYC 5244-00182-1 by (709) Fringilla - 2003 June 28:

An 8.83 second occultation was observed by John Broughton at Reedy Creek on the Gold Coast of Queensland using a manually timed CCD drift-scan technique. Comprehensive guidelines including subsequent improvements in the timing methods can be found here.

Fringilla CCD Drift-trail

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Occultation of TYC 0298-00715-1 by (100) Hekate - 2003 July 14:

An approx 4 second occultation was observed by Michael Mattiazzo in South Australia. Michael writes:

Disappearance At : 10:58:08
Reappearance At : 10:58:12

Occultation observed between 3.5-4.5 seconds duration. I used 2 timers, one to record the start of occultation accurate to the second, the other to record the duration of 4 seconds 0.5 second, unfortunately I don't have a timer with subsecond accuracy. I'll add a tape recorder to my shopping list.

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Occultation of TYC 8280-00410-1 by (372) Palma - 2003 July 15:

A 1.5 second occultation was observed by Ray Pickard at Bathurst Observatory. Ray writes:

Disappearance At : 13 53 36.85
Reappearance At : 13 53 38.38

Bagged another one! At a 1.5 sec dissapearance we would have been extremely close to the (possibly) western edge of the path. The star was harder to find than expected, possibly because the faintness at magnitude 13 was compounded by the light of the bright moon. But eventually it was successfully found in time. WWVH was strong and could be heard with Boulder, Colorado as well and recorded easily.

On another matter, for users who relied on Telstra: My estimate for the delay of the Telstra "1194" signal was as follows:
0.22 sec at 8:30 AM 15/07/03
0.12 sec at 21 hrs 15/07/03
0.06 sec at 13:30 16/7/03
This was determined by a combination of WWVH and BIPM (SNTP) at
http://www.bipm.fr/enus/5_Scientific/c_time/time_server.html after applying the delay estimate indicated.

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Occultation of HIP 88816 by (976) Benjamina - 2003 July 19:

Please refer to the separate Benjamina results page here.

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Occultation of TYC 6867-01386-1 by (165) Loreley - 2003 July 20:

A 13.2 second occultation was observed by John Broughton at Reedy Creek, Qld, using the CCD drift-trail method:

TELESCOPE DETAILS:
Aperture (cm)                    : 25
Focal length (cm)                : 183.5
Type (e.g. SCT; Newtonian)       : SCT
Magnification                    : CCD observation... 2.7"/pixel 
Observing site name              : Reedy Creek
Longitude (East +ve)             : +153.397
Latitude (South -ve)             : -28.110
Height above Sealevel (metres)   : 67

Sky Transparency (Delete two)    : Good
Star Image Stability (Delete two): Good
Other Conditions:  
     (Wind, Clouds, Lights, etc.): None

TIMINGS:  (PLEASE REPORT IN UNIVERSAL TIME)
Time Source (e.g. WWV, VNG)      : Digital clock syncronised to WWVH.
Recording method (e.g. tape)     : Estimated to the tenth of a second
                                 : the CCD camera shutter operations.  
Could you see the Asteroid?      : Visible during the occultation.
Approx. Limiting Magnitude       : 14
                                          | Estimated  |
                           Universal Time | Reaction   | Accuracy, Remarks
                              h  m  s     | Time (sec) | 
Started Observing          : 15:15:38.3         0        0.2
Disappearance At           : 15:16:50.73        0        0.2 absolute
Reappearance At            : 15:17:03.95        0        0.05 relative
Stopped Observing          : 15:18:09.6         0        0.2
Duration                   : 13.22 seconds

Loreley CCD Drift-trail

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Occultation of TYC 6250-00864-1 by (690) Wratislavia - 2003 July 24:

A 13.97 second occultation was observed by John Broughton at Reedy Creek, Qld, using the CCD drift-trail method. A 5.1 second occultation was also observed by Peter Anderson in Brisbane:

The following plot has been generated by WinOCCULT and supplied by Dave Herald:

  1    John Broughton, Reedy Creek, Qld (CCD)
  2    Peter Anderson, The Gap, Qld

Wratislavia Plot Observer : John Broughton Observing site name : Reedy Creek Longitude (East +ve) : +153.397 Latitude (South -ve) : -28.110 Height above Sealevel (metres) : 67 Time Source (e.g. WWV, VNG) : Digital clock syncronised to WWVH. Recording method (e.g. tape) : Estimated to the tenth of a second : the CCD camera shutter operations. Could you see the Asteroid? : Visible during the occultation. Approx. Limiting Magnitude : 14 | Estimated | Universal Time | Reaction | Accuracy, Remarks h m s | Time (sec) | Started Observing : 09:57:13.1 0 0.2 Disappearance At : 09:57:55.34 0 0.2 absolute Reappearance At : 09:58:09.31 0 0.1 relative Stopped Observing : 09:58:30.0 0 0.2 ADDITIONAL COMMENTS: CCD drift-scan observation as described for the 2003 June 28 Fringilla occultation. A fainter star and poor seeing conditions contributed to a less accurately defined duration which amounts to 13.97 0.1 seconds and a chord length of 125 km. Observer : Peter Anderson We had a visit from Bruno Sicardy and Thomas Widemann and both their partners. They are from the Paris Observatory and called following the IAU conference in Sydney (doing the tourist bit.). I showed them around (including a tour through the Brisbane Planetarium and they ended up at my house. To cut a long story short, time was pressing, and so they stayed and we observed the 690 Wrataslava event. They deferred to me to monitor it which I did between 09hrs 51min to 10hrs 06min. At 09hrs 58min 04sec (-1.0sec +0.25 sec), I noticed a drop but either it was gradual or the small nature of it was not instantly apparent, so I did not trgger a stopwatch but made a comment on tape. Then at 09hrs 58min 09.1sec (allowing for a 0.28sec reaction time,) full brightness returned instantly. I am 95% sure it was a 'real' event. Before I checked my tape, I had estimated that the drop was around 6 seconds duration and this is consistent with the tape. The star was clearly somewhat brighter than the asteroid and both Bruno and Thomas watched the merging and especially the separation. I believe that this was a different experience for them, since they usually set up their equipment to record the event electronically. It is somewhat academic to estimate the merging and separation times in view of the above, but I hasten to add that they are consistent with the event I am reporting.

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Occultation of TYC 6843-00322-1 by (27) Euterpe - 2003 July 27:

An occultation was observed by John Broughton using the drift-trail method as follows:

Observer's Name                  : John Broughton
Magnification                    : CCD drift-scan...5.1 pixels per second
Observing site name              : Reedy Creek
Longitude (East +ve)             : +153.397
Latitude (South -ve)             : -28.110
Height above Sealevel (metres)   : 67
Time Source (e.g. WWV, VNG)      : WWVH
Recording method (e.g. tape)     : Manually timed shutter operations 
                                          | Estimated  |
                           Universal Time | Reaction   | Accuracy, Remarks
                              h  m  s     | Time (sec) | 
   COLUMN FORMAT TO USE--->  __:__:__._        _._       _________________)
Started Observing          : 11:21:03.7         0        0.2 seconds
Disappearance At           : 11:21:42.3         0        0.2 seconds
Reappearance At            : 11:21:47.1         0        0.2 seconds
Stopped Observing          : 11:22:14.4         0        0.2 seconds
Duration                   : 4.8 sec

ADDITIONAL COMMENTS: 
CCD drift-scan observation being prior to August was manually timed. The magnitude 
drop for this occultation was only 0.36 and the outcome too uncertain to formally 
report it at the time. A more recent analysis using the whole width of the star trail 
on the Y axis instead of a single row creates a convincing enough dip in the profile.

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Occultation of TYC 5126-01557-1 by (205) Martha - 2003 August 06:

An occultation was observed by Peter Litwiniuk at Pakenham, VIC:

Observer                         : Peter Litwiniuk
Observing site name              : Pakenham, VIC
Longitude (East +ve)             : 145 29 00
Latitude (South -ve)             : -38 04 01
Height above Sealevel (metres)   : 62
Time Source (e.g. WWV, GPS)      : www.time.gov
Recording method (e.g. tape)     : manual
                                          | Estimated  |
                           Universal Time | Reaction   | Accuracy, Remarks
                              h  m  s     | Time (sec) | 
Started Observing          : 12:49:45
Disappearance At           : 12:52:37
Reappearance At            : 12:52:43
Stopped Observing          : 12:54:30

ADDITIONAL COMMENTS: 
The times are very rough because I used an analog watch to obtain them,
so obviously I had to look away from the eyepiece to see the time.
Also the watch itself was checked against www.time.gov website about
30 minutes after the event and found to be 2 seconds fast. This time 
has not been subtracted from the timings above (they are uncorrected timings.)

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Occultation of HIP 73161 by (481) Emita - 2003 August 10:

Please refer to the separate Emita results page here.

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Occultation of TYC 6168-00055-1 by (21) Lutetia - 2003 August 24:

A 3.8 second occultation was observed by John Broughton at Reedy Creek, Qld, as follows:

TELESCOPE DETAILS:
Aperture (cm)                    : 25
Focal length (cm)                : 183.5
Type (e.g. SCT; Newtonian)       : SCT
Magnification                    : CCD drift-scan...5.3 pixels per second
Observing site name              : Reedy Creek
Longitude (East +ve)             : +153.397
Latitude (South -ve)             : -28.110
Height above Sealevel (metres)   : 67

Sky Transparency (Delete two)    : Good
Star Image Stability (Delete two): Fair
Other Conditions:  
     (Wind, Clouds, Lights, etc.): None

                                          | Estimated  |
                           Universal Time | Reaction   | Accuracy, Remarks
                              h  m  s     | Time (sec) | 
   COLUMN FORMAT TO USE--->  __:__:__._        _._       _________________)
Started Observing          : 09:02:35.52        0        0.05 seconds
Disappearance At           : 09:03:49.36        0        0.05 seconds
Reappearance At            : 09:03:53.16        0        0.05 seconds
Stopped Observing          : 09:05:16.80        0        0.05 seconds

ADDITIONAL COMMENTS: CCD drift-scan observation. WWVH and the ticking
of a quartz digital clock was taped on separate channels prior to the
event. During the occultation, the ticking was recorded along with the
camera shutter. Audio analysis software was used to link the shutter
times to WWVH afterwhich a correction for propagation was applied. 

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Occultation of TYC6793-01107-1 by (503) Evelyn - 2003 August 30:

A 5.8 second occultation was observed by David Brock at Waharau, south of Auckland, NZ, as follows:

TELESCOPE DETAILS:
Aperture (cm)                    : 41cm 
Focal length (cm)                : 200cm 
Type (e.g. SCT; Newtonian)       : Newtonian 
Magnification                    : 125 
Observing site name              : Waharau 
Longitude (DD MM SS ; East +ve)  : 175 17 24.3 
Latitude (DD MM SS ; South -ve)  : -37 02 25.8 
Height above Sealevel (metres)   : 44m 
Geodetic Datum (e.g.WGS84,NZ1949): WGS84
Height Datum (if known)          : 

Sky Transparency (Delete two)    : Fair  
Star Image Stability (Delete two): Good  
Other Conditions:  
     (Wind, Clouds, Lights, etc.): 

TIMINGS:  (PLEASE REPORT IN UNIVERSAL TIME)
Time Source (e.g. WWVH, GPS)     : WWVH 
Recording method (e.g. tape)     : tape
Could you see the Asteroid?      : no
Approx. Limiting Magnitude       : 15.5
                                          | Estimated  |
                           Universal Time | Reaction   | Accuracy, Remarks
                              h  m  s     | Time (sec) | 
   COLUMN FORMAT TO USE--->  __:__:__._        _._       _________________)
Started Observing          : 10 50 00 
Disappearance At           : 10 53 53.2       0.5 sec    expecting it in 30sec 
Reappearance At            : 10 53 59.0       0.3 sec 
Stopped Observing          : 10 54 05 

ADDITIONAL COMMENTS: My first successful timing and in my excitement I
forgot to carry on observing after to watch for additional events.
I was surprised not to be able to see the Asteroid itself.

Another observer (not timing) using a 20cm Newtonian thought he saw a
Brief brightening of the star 1 sec after disappearance but this was not
observed by me.

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Occultation of TAC +10#06115 by (230) Athamantis - 2003 September 01:

An occultation was observed by David Higgins in ACT as follows:

TELESCOPE DETAILS:
Aperture (cm)                    : 203
Focal length (cm)                : 2030
Type (e.g. SCT; Newtonian)       : SCT
Magnification                    : 78
Observing site name              : Bredbo Hall
Longitude (East +ve)             : 149 08 44.3
Latitude (South -ve)             : -35 57 08.2
Height above Sealevel (metres)   : 717
Geodetic Datum (e.g.WGS84,NZ1949): WGS84

Sky Transparency (Delete two)    : Good
Star Image Stability (Delete two): Good
Other Conditions:  
     (Wind, Clouds, Lights, etc.): Cold, no wind to speak of and no
cloud

TIMINGS:  (PLEASE REPORT IN UNIVERSAL TIME)
Time Source (e.g. WWVH, VNG)     : WWVH
Recording method (e.g. tape)     : Tape
Could you see the Asteroid?      : No
Approx. Limiting Magnitude       : 12.8
                                          | Estimated  |
                           Universal Time | Reaction   | Accuracy,
Remarks
                              h  m  s     | Time (sec) | 
   COLUMN FORMAT TO USE--->  __:__:__._        _.__________________)
Started Observing          : 11:17:00.0
Disappearance At           : 11:18:54.3	     1.0       Dimmed
Reappearance At            : ??:??:??.?                Not observed
Stopped Observing          : 11:20:00.0

Was your reaction time (also known as Personal Equation) subtracted from
any of the above timings?  : No

ADDITIONAL COMMENTS: Target star was always in view.  Distinct dimming
at merge but the brightening event was not obvious.  However, after 1 minute I
could clearly see the star had returned to full brightness

I had aimed to trial my video setup but I only finished identifying the
target star with 15 minutes to spare (visually), giving me insufficient
time to strip the EP and attach the camera, refocus and ID the target.

After the event I attached the camera but failed to achieve focus.  It
turns out that the limiting magnitude of the camera/scope setup may be
considerably less than I would like - perhaps only around magnitude
9-10.  More testing will be required.

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Occultation of TYC 6267-01475-1 by (336) Lacadiera - 2003 September 18:

An occultation was observed by Stephen Kerr in Rockhampton as follows:

TELESCOPE DETAILS:
Aperture (cm)                    : 25
Focal length (cm)                : 150
Type (e.g. SCT; Newtownian)      : Newtonian
Magnification                    : 83 X
Observing site name              : Rockhampton Qld
Longitude (East +ve)             : +150 29' 58.06" (AGD 1984)
Latitude (South -ve)             : -23 16' 15.04" (AGD 1984)
Height above Sealevel (metres)   : 50

Sky Transparency (Delete two)    : Good
Star Image Stability (Delete two): Good
Time Source (e.g. WWV, VNG)      : WWVH
Recording method (e.g. tape)     : Stopwatch
Approx. Limiting Magnitude       : 13.2
                                          | Estimated  |
                           Universal Time | Reaction   | Accuracy, Remarks
                              h  m  s     | Time (sec) | 
Started Observing          : 11:52:00.0
Disappearance At           : 11:54:26.4		0.6
Reappearance At            : 11:54:33.2		1.0
Stopped Observing          : 11:55:00.0
Duration                   : 6.8 sec

ADDITIONAL COMMENTS: I should start by saying that I was quite unhappy with this observation.
The disappearence caught me a little by surprise - during a blink and it was around 20 seconds
earlier than I was expecting. The reappearence was so gradual that it was more or less 
impossible to time.  There is an element of doubt in my mind that I returned to the wrong part
of the field after the 'blink' and that I didn't really see a reapperence at all but I would
have to rate this as a less than even probability.  This event has done nothing but strengthen
my resolve that I need video to do this business properly.

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Occultation of TYC 6855-02884-1 by (259) Aletheia - 2003 September 29:

Please refer to the separate Aletheia results page here.

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Occultation of TYC 0861-00641-1 by (219) Thusnelda - 2003 October 18:

Please refer to the separate Thusnelda results page here.

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Occultation of TYC 7399-01065-1 by (99) Dike - 2003 October 20:

An occultation was observed by David Herald in ACT as follows:

TELESCOPE DETAILS:
Aperture (cm)                    : 20
Focal length (cm)                : 74
Type (e.g. SCT; Newtonian)       : Newtonian
Magnification                    : 100
Observing site name              : Cooma
Longitude (East +ve)             : 149 08 43.0
Latitude (South -ve)             : -36 14 21.0
Height above Sealevel (metres)   : 831
Geodetic Datum (e.g.WGS84,NZ1949): WGS84
Height Datum (if known)          : 

Sky Transparency (Delete two)    : Good  
Star Image Stability (Delete two): Good  
Other Conditions:  
     (Wind, Clouds, Lights, etc.): 
Time Source (e.g. WWV, GPS)      : WWVH
Recording method (e.g. tape)     : Tape
Could you see the Asteroid?      : No
Approx. Limiting Magnitude       : 12
                                          | Estimated  |
                           Universal Time | Reaction   | Accuracy, Remarks
                              h  m  s     | Time (sec) | 
Disappearance At           : 11 37 21.0        0.3       Definite
Reappearance At            : 11 37 25                    Almost certainly missed - moved head at wrong time!

Was your reaction time (also known as Personal Equation) subtracted from 
any of the above timings?  : 
If YES, state value        : Yes - as given above

ADDITIONAL COMMENTS:
I observed the D of this event last night. the R - well, I chose to move my
head at the wrong time, I think excitement etc). Possible R's were 25.0 or
29.0 - but all far too long for a 2.1 sec predicted event.


Albert Brakel reported:
TELESCOPE DETAILS:
Aperture (cm)                    : 20 cm
Focal length (cm)                : 200 cm
Type (e.g. SCT; Newtonian)       : SCT
Magnification                    : 118x
Observing site name              : Hill 1.3km S of Bredbo
Longitude (East +ve)             : +149 08' 33"
Latitude (South -ve)             : -35 58' 06"
Height above Sealevel (metres)   : 745 m
Geodetic Datum (e.g.WDD84,NZ1949): GDA94
Sky Transparency (Delete two)    : Poor
Star Image Stability (Delete two): Poor
Other Conditions:  
     (Wind, Clouds, Lights, etc.): Many scattered clouds moving across
Time Source (e.g. WWV, VNG)      : WWVH
Recording method (e.g. tape)     : Tape
Could you see the Asteroid?      : No
Approx. Limiting Magnitude       : c. 11
                                          | Estimated  |
                           Universal Time | Reaction   | Accuracy, Remarks
                              h  m  s     | Time (sec) | 
Started Observing          : 11:34
Disappearance At           : 			No event between 11:36:55 - 11:37:20.8
Stopped Observing          : 11:39

ADDITIONAL COMMENTS: A constant battle with clouds moving across, resulting in numerous breaks 
in observation between 11:34 - 11:39. The star was definitely visible in the interval 11:36:55 - 
11:37:20.8, near the predicted time of the event, which was ended by the star's disappearance 
(like all the other stars in the field) by a gradual dimming due to cloud. Perversely, the only 
area of the sky affected by the cloud was the west, where the appulse was.

[It appears that Albert was clouded out approximately two seconds before the occultation at 
his location].

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