recent occultation by this 108km diameter asteroid observed in the US,
indicates a possible binary structure or some exaggerated relief like
a crater. The Journal for Occultation Astronomy
 (JOA), describes the observations in detail and the theory
put forward to explain a double (full extinction) occultation recorded
by Drift Scan . One chord
More observations are requested.
next occultation is over the British Isles on 2020 Jan 26 at 05:26 UT,
 Drift scan Timing by John Broughton
chords will improve the shape profile of (814)Tauris. The paper in JOA
lists the events where chords were obtained in the past. Five predictions,
but no more than 2 positive chords in any one event. The asteroid is
most likely a rotating object so the profile may be time dependant.
Rotation light curve observations in the ALCDEF
 database indicate only a small magnitude differential of
about 0.1 mag and no clear light curve.
prediction for Tauris:
Prediction made on 2019 July 11th
star : UCAC4 403-066026 ( GSC 5630-511) in Ophiuchus
Magnitudes: v 12.9, r 12.0
Magnitude drop: 3
Maximum duration 3.9s
of 5 degrees:
field of 0.5 degrees
Tips for observers / recorders:
1 ) Please observe even if you are outside the dotted line limits.
These observations may be negative or short duration.
2 ) If you use a mobile telescope, then make notes on its location so
that we can get its coordinates from Google Earth.
2. Planetary Cameras:
1) If possible use a focal reducer to get F3 to F5 or thereabouts.
This usually applies to SCT
2) Download and install Dimension
4 software and use it to update the computer clock 10min before
3) Use the camera software control to add the UT time stamp to the frames.
This can be done with SharpCap
and FireCapture (or other products).
4 ) Select an integration time that records the target star clearly
6) The integration time (or exposure) is likely to be 0.1 to 0.5sec.
The shorter the better, but this will depend on your telescope and sky
7) Record in the format (SER or AVI) which shows the time stamps clearly.
8) Observe/record for a minimum of 3min around the predicted mid time.
9 ) Use a clear filter, or no filter.
10) The desired UT accuracy is +/-0.1 sec
3. Video cameras
1) Record analogue video in AVI format using a USB-2-digital
converter (e.g. Pinnacle) and VirtualDub
software, or possibly Sharpcap (untried).
2) Introduce time onto the video frame during recording with a GPS Video
Time inserter if you have a VTI such as
Note how you time the occultation in a written log book.
1) The observer should play back the file and note the approximate times
of any events. A software analysis will be needed to extract the exact
2) There is a free software tool (TANGRA)
if the observer does the analysis, otherwise send the file to the writer
for analysis (drop box, wetransfer etc).
3) Negative result (no occultation) are as important as the positives.
Please report negatives or "unsure".
4) There is standard report to fill out. Contact me if you have a successful
Tim Haymes: occultations AT stargazer DOT me DOT uk
Assistant Director, BAA Asteroids and Remote Planets Section,
[ PS: If you see any typos, drop me an email
thanks :-) ]
About occultations and this page:
This is a personal web page to support occultation observers. There
is a discussion group https://groups.io/g/UKoccultations
which observers are welcome to join. An observation sent to the writer
is checked and forwarded to the British Astronomical Association (BAA)
which will perform a preliminary analysis prior to submission to IOTA-ES.
Occult-4 software by Dave Herald was used to compute the predictions.
Nearer the time, an update may appear from Steve Preston (IOTA)
OccultWatcher software by Hristo Pavlov is used to present the ground
maps for planning observer locations when these become available.
SkyMap pro 11 was used to present the path on the sky and the star fields.
Page created: 2019 July 11