Dutch Occultation Association
ESOP XXV
25th European Symposium on Occultation Projects
25th-27th August 2006
Papers and Proceedings
Alphabetic order of lectures ESOP XXV
  1. Wolfgang Beisker (D)
    Towards a New Occultation Camera: Investigation of CCD Chips
  2. Wolfgang Beisker (D)
    The Pluto occultation on the 12th of June 2006.... The atmosphere is still alive!
  3. Hans Joachim Bode
    ESOP I – ESOP XXVA brief Review of its History and Highlights
  4. Hans Joachim Bode
    Determining Variations of the Diameter of the Sun
  5. Dr. Eberhard Bredner
    My twenty five years of video observation
  6. Hans-Hellmuth Cuno (D) & Harrie Rutten (NL)
    Optical Time Inserter for Webcams
  7. Thomas Flatres (F)
    How to manage several consecutive occultations
  8. Adri Gerritsen (NL)
    Computer simulations of the Bailey's Beads
  9. Hans Govaarts (NL)
    How DOA prepares expeditions to grazing occultations in the Netherlands
  10. Martina Haupt
    Bailey's Beads in Tunisia
  11. Detlev Koschny (NL)
    Smart-1 will impact the Moon - proposed observations and expected results
  12. Detlev Koschny (NL)
    The Koschny Observatory - A new private observatory in The Netherlands
  13. Eric Limburg (CH)
    LOW 4.0 ? the latest developments
  14. Pawel Maksym (PL)
    Faint star grazing occultation registered in Poland
  15. Pawel Maksym (PL)
    Total Solar Eclipse Polish Expedition Egypt 2006
  16. Jan Manek (CZ)
    Small too for total occultation observers (SW for PDA)
  17. Jan Manek (CZ)
    [on behalf of Petr Mudra (CZ)]

    Simple chronograph ACH 77
  18. Jan Manek (CZ)
    [on behalf of Peter Zboncak, Roman Piffl and Ivan Majchovic (SK)]

    Invitation for ESOP XXVI in Bratislava
  19. Wim Nobel (NL)
    A brief history of the Leiden observatory
  20. Wim Nobel (NL)
    Occultation of Regulus by Rhodope
  21. Andrei Plekhanov (RU)
    Using OrbFit Linux version to making asteroid orbit updates
  22. Steve Preston (USA)
    Asteroid Occultation Prediction Process
  23. Steve Preston (USA)
    Extracting Quantitative Data from Video Recordings
  24. Vaclav Priban (CZ)
    Using of the Occultation Technique for Measuring
    of the Sun Chromosphere Thickness
  25. Harrie Rutten (NL)
    Optical improvement in Cassegrain like telescope systems for observing occultations
  26. Carles Schnabel (ES)
    Our grazing observation of the annular solar eclipse on 2005 Oct 3rd
List of Poster Sessions ESOP XXV

Pawel Maksym (PL)
Total Solar Eclipse Polish Expedition Egypt 2006*

Eberhard Bredner (D)
GRAZE-MISSES and their documentation for further expeditions
* Pawel has a lecture with the same title.

D e t a i l s l e c t u r e s

Dr. Wolfgang Beisker (D)
International Occultation Timing Association / European Section Research and Development

Dr. Wolfgang Beisker

Towards a New Occultation Camera: Investigation of CCD Chips
30 min.

(IOC) is coming out of age. It is still a very useful system, but occultations of stars fainter than mag 14 with a 0.7 seconds exposure time are problematic. The TC245 chip used in the camera is about 20 years old, It can be found in a catalogue of Texas Instruments around 1987, and the design is older anyway. Its inherent readout noise, which can hardly be overcome, is about 30 electrons. This is a rather limit to the detectibility of faint stars, if short exposure times are to be used.

The recent occultations of Charon (2005) and Pluto (2006) with stars in the range of mag 15 as well as the outlook for occultations by TNO's have shown, that exposure times shorter than about 1 second can only be achieved with telescopes in the 1m class. Because the scientific competition around the world by specially US groups let us think about new camera designs.

In this presentation the advancement of technology by intensified chips (L3Vision CCD (c) E2V) and ICCD chips will be discussed in general with special respect to the occultation application.

Because of the high price of these chips, it may be necessary to select a relatively small chip size, such as about 128 times 128 pixels. In order to have a large field of view even with bigger telescopes for finding the object, the combination with a standard video CCD system such as the WATEC or MINTRON system is necessary including Flip Mirror technology.

Computer simulations will show, what new camera designs can bring for us.

This would lead to the development of a new Occultation Camera, which will let IOTA to play a front role in occultation observations for the next 10 or 20 years.

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Dr. Wolfgang Beisker (D)
International Occultation Timing Association / European Section Research and Development

Dr. Wolfgang Beisker

The Pluto occultation on the 12th of June 2006.... The atmosphere is still alive!
30 min.

Multinational expeditions have been organized, to observe the occultation of UCAC 26039850 on the 12th of June, 2006. The target star was 15th magnitude, therefore only instruments larger than about 10 inch could successful observe this event. Professional and amateur astronomers took the chance, to get a glimpse of Pluto's atmosphere. The occultation track went across southern Australia, Tasmania, New Zealand and La Reunion as well.

A report is given about the preparation, observation, data analysis and first very previous results. The results can be summarized in the statement "Pluto's atmosphere is still alive!"

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Hans Joachim Bode
IOTA-ES

ESOP I – ESOP XXV
A brief Review of its History and Highlights

Members of the “Astronomische Arbeitskreis Hannover”, who were engaged in observing stellar occultations by planetary objects, once talked about possibilities in getting in contact to other European individuals interested to this subject.
Because of the fact that the Astronomische Arbeitskreis Hannover was computing predictions of grazing occultations for all interested observers all over Europe, they decided to invite these observers to a symposium being organized by them in Hannover. For the first time they came together talking about their interests, experience, plans and efforts.
In 1981 they were presenting their results and talking about future projects and possibilities:

ESOP I Hannover 1981-11-7

Jean Meeus Calculations of Occultations
Jean Bourgeois Personal Equation for Lunar Occultations
Kyril W. Fabrin Prediction Programs
Jukka Piironen Possibilities of Asteroidal Occultatons Observations in Finland
Wolfgang Beisker Theory and Observation Possibilities of the Central Flash (Venus/Nunki)
Wolfgang Beisker,
Hans-J. Bode
Reduction of Occultation Data (Graze of Aldebaran)
Wolfgang Beisker Principles of One-dimensional Image Analysis
Chistoph Bittner Design of a Portable Photometric Unit for Occultation Applications
Norbert Kordts Fundamental Concepts of
Microprocessor-controlled Photometric Systems
Bohumil Malecek Photometric Occultation Work at Valasske Mezirici
Martin Knitsch Demonstrations of Grazing Occultations of Venus / Aldebaran

NATIONAL OCCULTATION WORK
             Belgium: J. Reynders
             West-Germany: H.-J. Bode
                                    - Hannover: H.-J. Bode
                                    - Lübeck: I. Reimann

1982 (!) .... 2005
ESOP II Hannover 1983-03-19
ESOP III Valasske Mezirici 1984-08-31
ESOP IV Hove 1985-08-24
ESOP V Lodz 1986-08-28
ESOP VI Aalborg 1987-08-21
ESOP VII Valasske Mezirici 1988-08-26
ESOP VIII Freiburg 1989-09-01
ESOP IX Jena 1990-08-24
ESOP X Hannover 1991-08-16
ESOP XI Castel Gandolfo 1992-08-28
ESOP XII Roden 1993-08-27
ESOP XIII Cracow 1994-08-12
ESOP XIV Plzen 1995-08-25
ESOP XV Berlin 1996-08-23
ESOP XVI Cambridge 1997-09-05
ESOP XVII De Haan 1998-08-28
ESOP XVIII Stuttgart 1999-08-05
ESOP XIX Lodz 2000-08-25
ESOP XX Sabadell 2001-08-24
ESOP XXI Napoli 2002-07-19
ESOP XXII Trebur 2003-08-29
ESOP XXIII Paris 2004-08-28
ESOP XXIV Helsinki 2005-08-26

ESOP XXV Leiden 2006-8-25*

Wim Nobel
Leidse Sterrewacht (Leiden Observatory)
Hans Joachim Bode
ESOP I - ESOP XXV / A brief Review of its History and Highlights
Dr. Eberhard Bredner
My twenty five years of video observation
Wolfgang Beisker
The Pluto Occultation on the 12th of June 2006. The atmosphere is still alive !
Thomas Flatres
How to manage several consecutive occultations
Detlef Koschny
Smart-1 will impact the moon - proposed observations and expected results
Adri Gerritsen
Computer Similation of the Bailey's Beads
Hans-Joachim Bode
Status and Results of the Solar Eclipses in 2005 & 2006
Carles Schnabel
Our grazing observation of the annular solar eclipse on 2005 Oct 3rd
Martina Haupt
Bailey's Beads in Tunisia
Pawel Maksym
Total Solar Eclipse Polish Expedition Egypt 2006
Jan Manek
Small too for total occultation observers (SW for PDA)
Steve Preston
Analysing video's from occultations by asteroids
Vaclav Priban
Using of the Occultation Technique for Measuring of the Sun Chromosphere Thickness
Hans Govaarts
How DOA prepares expeditions to grazing occultations in the Netherlands>
Hans-Joachim Bode
Determining Variations of the Diameter of the Sun
Wim Nobel
Occultation of Regulus by Rodope
Pawel Maksym
Faint Star Grazing Occultation registered in Poland>
Wolfgang Beisker
Towards a New Occultation Camera:Investigation of CCD chips
Hellmuth Cuno & Harrie Rutten
Optical Time Inserter for Webcams
Jan Manek (on behalf of Petr Mudra)
Simple Chronograph ACH 77
Andrej Plekhanov
Using OrbFit Linux version to making asteroid orbit updates
Eric Limburg
LOW 4.0 - the latest developments
Detlef Koschny
The Koschny observatory - A new private observatory in the Netherlands
Steve Preston
Asteroid Occultation Prediction Process
Jan Manek
Invitation for ESOP XXVI

* (editors note: this is the preliminary program)

Have a look at the topics and compare them: Still interesting for everybody being interested in occultations over the years. A lot of planned projects could be realized in the end as a result of advancing computers and data acquisition systems. One of the highlights was the development of the IOC (IOTA-Occultation-Camera) which had been used ever since for measuring details of planetary atmospheres.
Future technologies one has never thought of in 1981, still lead to increasing chances and possibilities for amateurs detecting changes in the atmospheres of the outer planets and their moons or exploring exoplanets.
But the old “standards” should be taken into account too and included to the observing programs: Lunar occultations, totals and grazing ones are still be needed. Despite these technical efforts another important thing happened. In the beginning of the ESOP-era it had been decided that every two years an ESOP should take place behind the iron-curtain – but everything changed in 1989! For the first time the “1990 ESOP IX / Jena” had been planned and organized by GDR-amateurs and their “officials” – but that date no officials were present, except some coordinators of the “Kulturbund”.

Over the years a lot of observers came and went, but still observing occultations is a major project for professional and amateurs as well.

Hans Joachim Bode
IOTA-ES

Determining Variations of the Diameter of the Sun
co-authors: Reinhold Büchner, Alfons Gabel, Konrad Guhl

The solar eclipses of October 3rd 2005 and March 29th 2006 had been used to measure the diameter of the sun. Observers in Spain and Germany who attended these events sent their data to the reduction-team. Inspecting the base data different problems had been seen clearly at once:

  • Finding out the right time of exposure
  • Video-Systems: relative or GPS-time-insertion
  • Webcams: synchronization of time (audio <-> video-track).

Three software-systems had been used to investigate the data:

  • OCCULT
  • SUNBEADS (VER001)
  • SUNBEADS (VER002)

The 2 SUNBEADS-version differ concerning the moonlimb data: version-1 is working only using WATT’s mooncharts, whereas verion-2 is using the integrated actualized limb-data (all valuable observed occultations data being reduced by D. Büttner) that had been integrated. Both versions had been used due to the fact that version-1 computed the solar diameter of eclipses that have recorded in the past to receive comparable data to the results of version-2. These data had been compared to the results one can get using OCCULT.

Preliminary results will be presented.

2006-03-29 / Turkey – relative time-insertion (C. Tegtmeier)
WINOCCULT Situation
corresponding audio-track (GPS-controlled-computer-clock)
2006-03-29 Turkey(B. Thome: only audio-time-recording / post-time-insertion)
corresponding audio-track (GPS-controlled-computer-clock)
2006-03-29 Turkey
(A.Tegtmeier: Cuno-GPS-time-insertion / same position and time (!) like C. Tegtmeier)
Very preliminary result
     Better to much light...
Annular Eclipse 2005-10-03
Annular Eclipse 2005-10-03 (original and invertet).

... than not enough

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Dr. Eberhard Bredner
VdS, IOTA-ES, DOA

My twenty five years of video observation

Early in the eighties of the last century I was lucky to observe with one of the first 8 inch Schmidt-Cassegrain telescopes ( an orange Celestron ). Like me, some members of our local astronomy club worked on total and grazing occultations of stars by the moon. They wanted to show a broader publicity what they where doing during their nightly excursions. So we bought a small video-camera for security purposes to record the observations.
Our first event recorded was a grazing occultation of Aldebaran (alpha tau) February 12/13, 1981. Even then the video got a ‘’time code’’ on the audio trace – the original signal from DCF 77.5 – it sounds like the first broadcast from Sputnik.

During the time passed by video-cameras grew more and more sensitive, now I observe stars that are 10.000 times fainter as at the beginning! What a development. And the time code is now printed to the single frame by GPS-signals, due to the new Cuno-GPS-fed-time-inserter. For observations in the landscape a tool we appreciate very much.

We now feed our equipment with 12 volt from batteries and do not need anymore an outlet of 220/230 volt as in former times. It was always a great task to find a place for the observation not too far from an outlet! And due to better sensitivity we now video-record even occultations by Minor Planets and mutual events of Galilean satellites.

Always with the same old orange telescope that is now my own because
the astronomy club faded away....

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Prof. Dr. Hans-Hellmuth Cuno (D) & Ing. Harrie Rutten (NL)
IOTA-ES and DOA

Prof. Dr. Hans-Hellmuth Cunoand Harrie Rutten

Optical Time Inserter for Webcams
30 min.

Electronics for an optical time inserter
The final solution of the problem the unknown latency time of image capture devices is an optical time inserter. The time is displayed on an 8 digit LED display and projected onto the imaging device by means of lenses and mirrors.

The electronic part consists of a GPS-receiver with an attached electronic circuit, which receives the NMEA data stream and displays UT on the 8 digit LED display. The figure height of the display is 4.6 mm. The display can be dimmed, frozen (during exposure) and blanked (for dark fields). Other information can also be displayed as for instance the geographical coordinates.

Optics and mechanics for an optical time inserter
The method will be explained how the projection of the monochrome LED display will be done. Main problem is the space, which is available, in a standard web cam (for instance a Philips ToUcam). Especially the distance from the last lens surface to the CCD chip has to be very long, compared to the focal length of an objective to reach a relative compact design. Therefore a special lens design, called retrofocus objective, was needed. This has been designed by Harrie and is made of standard components from optical suppliers. The characters in the display of 4.5 mm have been reduced optically to a size of 0.2 mm!

General
Hellmuth and Harrie will show the status of this project. At the moment it is not sure a working model can be presented because some optical components which were chosen are not manufactured anymore and we had to make a full opto mechanical restart. But some results of experiments and simulations can be shown.

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Thomas Flatres (F)
IOTA-ES

How to manage several consecutive occultations
30 min.

The use of Watec camera have increased the number of performed occultations during the same night.
The use of prevision by low4 is help full to manage the process By modifying the software of the time inserter we can quickly change the star number, up date the geographic positions form a GPS and keep the time accurately.
By recording the video on DVD We are able to read directly the video on a computer, and keep pictures if needed.
Virtualdub in version mpg2 is able to sort true pictures with the two fields on it and if you need it is possible to get a pre determinate number of consecutive pictures from the record (odd fields, even fields or both fields)

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Adri Gerritsen (NL)
DOA

Adri Gerritsen

Computer simulations of the Bailey's Beads
30 min.

The most recent total solar eclipse visible from The Netherlands, could be witnessed on the 3rd of May1715. Unfortunately, this eclipse ? totality being visible only from the Wadden Islands ? was clouded out.
On the 17th of April 1912, however, the central line of a total-annular (hybrid) solar eclipse crossed the southern part of The Netherlands near Maastricht. In spite of the beautiful weather and the detailed observation reports, there is still a lot of discussion concerning the phenomena that could be seen during this memorable event. Some sources claim the eclipse was total during 0.25 seconds, while others describe it as an annular eclipse lasting for several seconds.

Almost one hundred years later, a computer model of the Bailey's Beads, developed by the Dutch Occultation Association, shows us in detail what actually could be seen on this special occasion. The model is based on the motion theory ELP2000-82B (Moon; Chapront) and VSOP87 (Sun; Francou / Bretagnon). Lunar limb data was taken from the Moonlimb database (Dietmar Büttner; version 1997). The ray-tracing algorithms were developed by the Dutch Occultation Association.

After a brief introduction to the algorithm, the reliability of the model will be examined by analyzing photo's taken during the annular solar eclipse of October 3rd 2005 near the central line (Madrid).

Predictions for the 1912 hybrid solar eclipse, made for 0.1 second intervals, have been merged into a movie that will show us the Bailey's Beads being visible for an observer on the central line near Maastricht.

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Hans Govaarts
DOA

Hans Govaarts

How DOA prepares expeditions to grazing occultations in the Netherlands
30 min.

How the Dutch do it ? It is the only question that will be answered during this lecture. The Preperation of expeditions takes far more time than the happening itself. Finding stations in a country that is very crowded with people and city-lights isn’t that easy.

The lecture will show you pictures of the preperation of a few grazes that will occur close to Emmen. One of them will be the Regulus-event in 2007. Also a failed attempt that occurred in 2004 will be discussed.

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Martina Haupt
ITOA

Bailey's Beads in Tunisia
30 min.

In October 2005 nine people travelled from Berlin to Tunisia to observe the annular eclipse of the sun on the 3rd of October.
There were five stations altogether: four stations in the grazing zones observing Bailey's Beads, two of them in the north and two of them in the south of the eclipse path. The fifth station was close to the central line where the ring could be observed.

The videotapes with the raw data of the stations that had successfully registered Bailey's Beads were evaluated at home. These data were processed by Konrad Guhl and Hans Bode with a computer programme written by Reinhold Büchner.

More details will be given in the talk, including detailed descriptions of all five stations, selection and setup of the equipment for successfully observing Bailey's Beads and a method to find the correct position for the observation as well as reactions of the local people.

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Dr. Detlev Koschny (NL)
ESA-ESTEC

Dr. Detlev Koschny

Smart-1 will impact the Moon - proposed observations and expected results
30 min.

In the night from 02 to 03 Sep 2006 around 02h15m UT +/- 7 hours, the European Space Agency's lunar spacecraft Smart-1 will impact the Moon. The impact was planned to be on the dark side of the Moon, but facing the Earth, such that it can be observed via telescopes. Current estimates of the impact flash brightness vary between 9 mag and 17 mag. A brighter flash from the leftover Hydrazin in the fuel tank is expected.

Several large telescopes are getting ready to observe the impact flash using imaging and spectrometric techniques. This will allow to study the detailed dynamics of the impact. Depending on the brightness of the impact it will also be possible to detect the flash and the ejecta cloud in smaller telescopes.

This presentation will address up-to-date (and much more precise) timing predictions, estimates for the impact magnitude. It will address the possibilities of observing the impact and the potential science return of the observations.

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Dr. Detlev Koschny (NL)
DOA

Dr. Detlev Koschny

The Koschny Observatory - A new private observatory in The Netherlands
15 min.

This presentation gives an overview over "The Koschny Observatory" in Noordwijkerhout, the Netherlands and its potential for observing asteroids and occultations.

Back Dr. Eric Limburg (CH)
DOA

Dr. Eric Limburg

LOW 4.0 - the latest developments
30 min.

The Lunar Occultation Workbench (LOW), version 4.0, has been under development for 5 years now. During ESOP XXV in Leiden the latest additions to its functionality will be demonstrated. Some highlights are:

    • Animations of stellar and planetary occultations!
    • Improved images of the moon by using Clementine data
    • First/last contact time and occultation duration for occultations of planets
    • Lunar occultations of the 12 brightest satellites in our solar system
    • Contrast/brightness controls, white/black sky, night vision (red)
    • Print occultation prediction lists (with figures!)
    • Creation of e.g. graze occultation summary reports and graze expedition invitations (in Word)
    • Launching Word, Excel and Outlook to view/edit/send LOW export files
    • GoTo functionality to steer your telescope to the occulted object
When will LOW 4.0 become available? It? s hard to say. But a free demo version will be given to all ESOP participants. The real thing can be downloaded once all integration and stress testing has come to an end, and that will take a few more months....

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Pawel Maksym Msc (PL)

Pawel Maksym (Astromax); Pawel Maksym (Astronomia)

Ary Sternfeld Planetarium and Astronomical Observatory in Lodz Polish Association of Amateur Astronomers Departmant of Position and Occultations

Faint star grazing occultation registered in Poland
20 min.

This lecture is a presentation of some results of faint star grazing occultations registered by observers of Department of Position and Occultations of Polish Association of Amateur Astronomers.

Fig. 1: Example of profile of faint graze observed by Poles


Fig.2: Another view of the same profile

Naturally in case of this kind of observations we have to ask about a need and sense of it.

There is also a problem of amount of observers which are able to registration of grazes with low magnitude stars.

One think is certain - when we are able to registration of faint stars grazes, total quantity of observable events is incredibly high.

Tekstvak: ??Fig. 3: Roman Fangor graze station ??
We hope that discusion on ESOP in Leiden will give us solution of all problems connected with this subject.

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Pawel Maksym Msc (PL)

Pawel Maksym (Astromax); Pawel Maksym (Astronomia)
Ary Sternfeld Planetarium and Astronomical Observatory in Lodz Polish Association of Amateur Astronomers Departmant of Position and Occultations

Total Solar Eclipse Polish Expedition Egypt 2006
20 min.

(Abstract is coming soon)

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Jan Manek (CZ)
IOTA-ES

Small too for total occultation observers (SW for PDA)
15min.

When observing total occultation by Moon, one has to utilize predictions. When only few event in night occur, this can be handled easily by beeping time signal and you memory. When there is more events or they follow one by other in short intervals, it's good to have a helper reading the predictions and announcing them. The author has used some 15 years ago a simple program on Sharp PC-1500 doing all this, but the predictions had to be entered by hand, which wasn't very comfortable. Therefore later when a PC become available in the dome beside the telescope, I've developed a DOS program doing this and directly reading predictions from Dave Herald's Win/Occult program. In current time small Pocket PC (PDA) computers are becoming more and more common. Therefore I've asked a friend of mine and he 'ported' this program to PocketPC environment. In this presentation you will see what a beta version of this program can do and comment them.

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Jan Manek (CZ) [on behalf of Ing. Petr Mudra]
IOTA-ES [Petr: Occultation and Astrometry Section of Czech Astronomical Society]

Simple chronograph ACH 77 including demonstration
20 min.

The chronograph ACH 77 was developed as a simple and cheap time recorder for visual observers instead of electronic stopwatch, usually used by occultation observers. This device is designed as a handy personal electronic instrument with the one or two inputs (for an one or two observers). It is based on an ATMEL microcontroller (AT89LP2052), powered by 9V miniature battery. The captured time moments and any other items are displayed on the alphanumerical LCD display with backlight and stored into the memory (max. 35 observations).
The control of this instrument is managed by two pushbuttons only and the time capturing is performed through an external contact (switch). The scientific time signal DCF 77,5 kHz (detected by CONRAD DCF receiving module) is decoded by the microcontroller and the time synchronization with internal chronograph time is performed. The captured time moments are stored into the memory with the accuracy 0.01 sec. and it is possible to display them at any time, until they are cleared by the operator. A simple personal delay measuring is also possible, so this feature allows to eliminate the reaction time of an observer. The chronograph can be equipped with a serial channel RS232 too, and any displayed time moment could be sent (as ASCII message) to the printer or to the PC, PDA etc. This is the way for keeping unrestricted number of captured time moments. The chronograph is now available as a kit version (on the printed circuit board 50 x 150 mm ? fully workable + DCF 77 kHz module) or final form, where the board including battery are placed in the plastic box.

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Jan Manek (CZ) [on behalf of Peter Zboncak, Roman Piffl and Ivan Majchovic (SK)]
IOTA-ES [Peter, Roman and Ivan: Astronomical Society Slowakia]

Invitation for ESOP XXVI
ESOP XXIV 2007 (24 - 26 August High Tatras Slovakia)
15 min.

Due to several circumstances it is not possible Peter Zboncak, Roman Piffl and/ or Ivan Majchovic can notcome ESO XXV.
They organise the next ESOP in Bratislava. Jan Manek will invite you to join the next ESOP.

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Wim Nobel (NL)
DOA

A brief history of the Leiden observatory
20 min.

The Leiden University was established in 1574 by Prince William the Silent as a reward to the Leiden citizens for their resistance against the Spanish conquest. Although an astronomical observatory is known to have existed since 1632, astronomical science was almost entirely theoretical and mathematical until the arrival of Dr. Friedrich Kaiser in 1827. During his directorship plans to build a modern observatory were made and in 1861 it was officialy opened. Throughout the years Leiden has known quite a few reknown astronomers, like Van de Sande Bakhuijsen, Hertzsprung, De Sitter, Oort, van de Hulst, and present day Icke and Van Dishoeck. Although the emphasis has always stayed theoretical, some important observational projects were conducted from Leiden (astrometry, timekeeping, double stars). Four historical instruments are nowadays present in the observatory: a 6 inch refractor of 1840 (wood, brought from the former observing tower of the academy building), a 10 inch Clark refractor of 1890, a 33 cm/18 cm double photographic refractor and a 45 cm Cassegrain-Coudé reflector called "Zunderman" for photometric purposes. These instruments are nowadays used and maintained by an amateur working group "Leidse Sterrewacht", which is a denomination of the KNVWS (Koninklijke Nederlandse Vereniging voor Weer- en Sterrenkunde - Royal Dutch Association of Meteorology and Astronomy). Members of this group conduct their own observation program here and assist in the maintenance of the instruments and giving guided tours to the public and on special occasioons, like the ESOP conference. At least three observers (Lex en Ingeborg Blommers, Wim Nobel) are known to have observed occultation phenomena from here. Both the Mercury (2003) and the Venus (2004) transit were observed here and recorded by Marius Püttmann. An occultation of Saturn by the Moon (2001) was photographed by Arie Hamer, only showing part of the rings outside the edge of the Moon.

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Wim Nobel (NL)
DOA

Occultation of Regulus by Rhodope
15 min.

On 19 October 2005, the bright star Regulus was occulted by the minor planet Rhodope. I was able to observe this phenomenon from the south of Spain with naked eye, as well as record a video tape with an ordinary camcorder. Both methods established a duration of 1,94 s, quite longer than the predicted maximum duration of 1,1 s. This result was confirmed by other observers in the predicted path. Also some observers north and south of the predicted path recorded a short occultation. This all leads to the conclusion that Rhodope is considerably larger than assumed. Since most assumed diameters of minor planets are based on measured brightness and a mean value of the albedo, one must conclude that Rhodope is considerably darker than this mean value. According to Dave Herald, the assumed diameter was 35 km, but the observations are consistent with 60 km, which is also the value derived from photometric studies.

My video also suggests a gradual disappearance and reappearance of Regulus. If this is a real effect (i.e. outside the earth's atmosfere) this could be a measure for the angular diameter of Regulus. Calculations, conducted by Raymond Dusser indicate that the assumed diameter of Regulus of 1.4 mas would lead to a gradual effect of 0.09 s, of which half would consist of a drop of 0.75 m. This could have been registered by my video because it operates at a rate of 25 images per second. However, the occultation took place at low altitude and my video also indicates that the seeing was not very good that night. Any conclusion based on the gradual dis- and reappearance on my video alone should therefore be considered as preliminary. 

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Dr. Andrei Plekhanov (RU)
Natalia Nesterova Institute

Using OrbFit Linux version to making asteroid orbit updates
15 min.

Observations of stellar occultation by asteroids are extremely important since they can provide unique information. To observe such events asteroid orbit should be calculated very accurately. Asteroid orbit elements can be found in astorb.dat file but for occultation predictions these elements have too big uncertainty. To calculate precision orbit elements OrbFit application is used. OrbFit is Open Source Fortran program used for asteroid orbit study created by OrbFit consortium. In particular one OrbFit mode is a calculation asteroid orbit elements by using a set of observations. There are several OrbFit versions:

  • version 2.3 which is based on Fortran77 and available for UNIX and
    WINDOWS operating systems.
  • Version 3.0 is based on Fortran90 and available only for UNIX.
OrbFit can be used on Linux operating system because Linux is a UNIX-like operating system. I selected OrbFit Linux version to make asteroid orbit updates because Linux is very stable and reliable and application LinOccult which I developed two years ago for occultation predictions calculations is also developed for Linux platform.

To compile OrbFit 2.3 version you need to have a regular Fortran GNU compiler which is a standard tool on Linux platform. But OrbFit 3.0 compilation is required advanced compiler because this version is based on Fortran90 which is not supported by GNU Fortran compiler. To compile OrbFit 3.0 I used INTEL Linux Fortran compiler which is available for free for personal and reasearch applications.

When OrbFit was compiled I found out that additional work is required to force OrbFit to produce results because even test examples from OrbFit package work incorrectly. Steve Preston help me a lot to tune OrbFit. He send me a patch to update OrbFit source code and configuration file with parameters to run OrbFit. Because Steve using OrbFit 2.3 for WINDOWS the first question was is results for Linux and WINDOWS platform will be the same.
Fortunately Steve and I got the same data. So I desided to use OrbFit for Linux version 2.3 because there is no patch for version 3.0. To use OrbFit for making asteroid orbit update you should have a set of observations in MPC and/or OrbFit internal formats. OrbFit convert observations from MPC format to internal format and start calculation.
Historical observations are available on OrbFit site presented in internal format for version 3.0. Unfortunately OrbFit version 2.3 internal format is different with version 3.0. If version 2.3 is used convertion to version 2.3 format is needed. OrbFit has many configuration parameters. To get good result user should provide appropriate configuration file because default parameters value are not tuned enougth.

In conclusuion I can note that OrbFit application is the best available application to making asteroid orbit updates but installation and tuning procedures for OrbFit are not a trivial tasks.

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Steve Preston (USA)
IOTA

Asteroid Occultation Prediction Process
30 min.

Many people across the world collaborate in the process of predicting the path of asteroid occultations.As a first step we identify asteroid occultations that are good candidates for observers.Then we refine the path prediction using new astrometry of the asteroid or the star.And, finally, we distribute the path predictions to potential observers (typically via website or email). In this talk I will identify the primary sources of the events posted to this website and describe the methodology I follow to generate path predictions for these events.More specifically, I will describe my approach for fitting an asteroid orbit, computing a star position from catalog data, and generating the actual path prediction for an event.

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Steve Presten (USA)
IOTA

Extracting Quantitative Data from Video Recordings

30 min.

The falling cost of very sensitive video cameras has encouraged many observers to record occultations with video equipment. Video recording is an excellent methodology because it provides an accurate record of the events free from fatigue and other problems that affect visual observations.
Video recording also provides very accurate timing if coupled with a good time signal. For many recording setups the observer can determine event times by simply stepping through the video frames and noting the times of events. However, dim stars and events with small magnitude drops can be difficult to measure with this simple visual review. Kazuhisa Miyashita of Japan has developed a program, LiMovie, which can measure the intensity of a star in a video recording. With LiMovie the observer can generate quantitative plots of intensity versus time. The resulting intensity plot is very useful for determining accurate times for video recorded occultations. In this talk I will provide a demonstration of using LiMovie to determine times for an asteroid occultation.

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Ing. Vaclav Priban (CZ)
PLANETARIUM Praha

Ing. Vaclav Priban

Using of the Occultation Technique for Measuring of the Sun Chromosphere Thickness
15 min.

This contribution describes technical solution for measuringof the thickness of the Sun chromosphere by only one telescope equipped with two TV cameras. Solution is based on using of a binocular adapter, solar filters and a special electronic circuit which fused both TV signals into one with some additions. It uses time inserter and evaluation reminds Venus transit.

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Ing. Harrie Rutten (NL)
DOA

Optical improvement in Cassegrain like telescope systems for observing occultations
15 min.

A very annoying problem when using cassegrain like telescopes for observing occultations is the internal reflections in the baffle tube. Especially when observing occultations when the Moon is nearly full gives a big loss of the limiting magnitude. Presented is a method to reduce the reflections in the focal surface of the telescope when using small fields
(for instance in using web cams).

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Carles Schnabel (ES)
IOTA-ES

Our grazing observation of the annular solar eclipse on 2005 Oct 3rd
15 min.

Six stations of the Agrupació Astronòmica de Sabadell were established on the northern limit of the eclipse in order to record six different Baily beads sequences. The preliminary results are presented, consisting on the different video files and the resulting hundred of timings measured. These data combined with others recordings obtained at the same northern limit and also at the southern, are being analyzed with the assistance of specialized members from IOTA/ES.

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