Agenda

Today:   Time of rise and set of Sun and Moon.
     
Aug. 24.-25, 2024   The 43th ESOP will take place at Planetarium Stuttgart, Germany.
Click for more information.
     
Predictions / Urgent Calls
for observation:
  Predictions of Asteroid Occultations for Europe
   ==> "Where to go, what to do, when to look" by Oliver Klös, IOTA/ES.
     
    Asteroid Occultations Updates by Steve Preston.
     
    Beobachtungsvorhersagen (Forum der Vereinigung der Sternfreunde e.V.)
     
Moon:   Grazing Stars brighter than 7.0 mag: GRAZPREP
     
Planets:   Occultations of Planets by the Moon (IOTA/ES).
     
Mutual conjunctions
of the Planets
by Dave Herald:
 
Date: Time: Separ.: Elong.: Planets:
2024 Jun 04: 10:30 UT 6.8' 13w Mercury & Jupiter
2025 May 24: 23:24 UT 7.5' 6w Mercury & Uranus
2026 Mar 07: 11:24 UT 4.0' 14e Venus & Neptune
2026 Jul 04: 06:12 UT 6.3' 38w Mars & Uranus
2029 Mar 27: 21:30 UT 6.5' 2e Venus & Neptune

Chronicle

May 4, 2024:   The 3. SOTAS-Meeting was held at the observatory Bülach. After the new IOTA/ES rules concerning the reporting of stellar occultations came into force, the meeting was planned as a workshop. During the 6 parts of the workshop, the participants learned the procedure of recording and reporting step by step. The protocol (see below) includes all necessary information and some impressions of this successful day.
Invitation,   Protocol,   SAG Blog
     
March 20, 2024:   Now it's official: The Minor Planet Center confirms the discovery of a satellite of (5457) Queen's. The discovery bases on two stellar occultations, made within 15 days. The first occultation resulted in three positive chords. Two of them were made by .... Stefan Meister and Andreas Schweizer !!! Congratulations, well done boys!
For further information, please read the Minor Planet Bulletin MPB.
See also the News entry of November 16, 2023.
     
Feb. 24, 2024:   New rules: The observation of star occultations by asteroids is useful scientific work and is becoming increasingly important. At the same time, the requirements for accuracy in recording and evaluation are increasing. For this reason, new rules apply for reporting in the SODIS portal. In particular, there are some mandatory files that must be uploaded for both positive and negative observations. The new rules are effective immediately and showed here (see point 1) for positive and point 2) for negative observations).

Standardized naming: Beside of the SODIS portal, our working group maintains an archieve, containing all observations of the members. It is important that each individual file can be clearly assigned to an event, an observer and a location. It should also be possible to search the archive specifically, e.g. by date, observer, asteroid, location, content, etc. For this reason, all files have so far been (re)named accordingly. It would be desirable if all files were named according to the same scheme (see point 3).
     
Feb. 05, 2024:   Great success for the "Alagasta-Team": Stefano Sposetti organized an observing campaign along the shadow path, which was generated by (738) Alagasta during its occultation of a 11.6 mag star. The observing team consisted of experienced observers as well as of young students (summarized in the station BEL). See the detailed recordings here.

Thanks to an excellent preparation and good weather conditions, the result is very impressive:
    Chords:      Video from Andrea Manna:       Congratulations to this great teamwork!
     
Dec. 12, 2023:   Once in a lifetime: The small asteroid (319) Leona passed in front of the red giant star Betelgeuse (alpha Orionis) on December 12, 2023 between approx. 01:10 and 01.16 UT (depending on the observing location). Dozens of amateurs traveled with their mobile equipment as close as possible to the center of the shadow path, which stretched from Greece through the southern parts of Italy, Sardinia, Spain, Portugal and on to Florida. Most of the observers were lucky with the weather. Many light curves were recorded and are now waiting to be analyzed.
 
As already suspected, the relatively small asteroid (approx. 80 x 55 km) was not able to occult the red giant completely. This is because the star has a small but already significant angular extent (approx. 50 milliarcseconds) due to its size (760 times the size of the sun) and proximity (550 light years). As a result, the star's drop in brightness during the occultation by (319) Leona (relative speed approx. 10 km/s, duration about 12 s) was not abrupt, but gradual. The otherwise 0.5 mag bright Betelgeuse became fainter by about 2 magnitudes, but was still clearly visible to the naked eye.
 
Three amateurs (Stefano Sposetti, Stefan Meister and Andreas Schweizer) from the SAG specialist group SOTAS (Stellar Occultation Timing Association Switzerland) traveled to the shadow path. The recorded light curves are shown below. Congratulations on their great success! The chords of all existing recordings are currently being calculated, which will make it possible to determine the shape and size of the asteroid as well as the position and size of Beteigeuze. We can look forward to it!
 
See all recordings here.
                        
 
Read the story to the following pictures:
                                  
 
See the preliminary results.
     
Nov. 30, 2023:   On Dec. 12, 2023, the bright and giant star Beteigeuze will be occulted by (319) Leona. For precise predictions, the orbital parameter of Leona should be known as precise as possible. Great: Just a few days before the big event, Stefan Meister and Peter Englmaier observed successfully a previous occultation of (319) Leona! On Nov. 30, 2023 and in parallel to Karl-Ludwig Bath (IOTA/ES), they used a telescope of the VdS Remote Observatory located at the Hakos farm in Namibia. This important observation allowed to actualize the orbital parameters of the small asteroid just in time. Well done!
See Recordings
     
Nov. 16, 2023   Great News: CBET reports the discovery of the probable binary nature of the minor planet (5457) Queen's. On Sept. 04, 2023, Stefan Meister (EGL) and Andreas Schweizer (BUE) recorded the light drop during a stellar occultation caused by the asteroid. Further observations by IOTA/ES members (about 15 days later) showed a double drop during the same occultation. The analysis of all available observations suggests that (5457) has a satellite.
Please read the corresponding CBET, the IOTA/ES Press Release the Sky & Telescope contribution and the Minor Planet Bulletin MPB.
     
September 04, 2023:   Congratulations again! Stefan Meister and Andreas Schweizer recorded for the first time an occultation caused by the asteroid (5457) Queen's! The small asteroid (about 20 km diameter) occulted the star, viewed from both locations EGL and BUE.
Video,  Chord
     
December 10, 2022:   Congratulations! The Uranus Moon (P7M03) Titania (III) occulted the Star UCAC4 531-004984.
During 73.0 sec (!!!) this occultation was observed by Stefano Sposetti. Have a look to the Lightcurve.
     
October 29, 2022   The 2. SOTAS-Meeting was held at the observatory Mirasteilas in Falera, Switzerland. Totally 12 participants listened to the lecturers, exchanged their experiences and discussed important points.
Invitation,   Protocol,   DVTI+CAM,   mobile Observations with telescopes
     
September 10/11, 2022:   This year, the 41th European Symposium on Occultation Projects (ESOP) took place at Granada, Spain.
Follow the YouTube videos to see the sessions:
- Saturday morning
- Saturday afternoon
- Sunday morning
     => The contribution of Andreas Schweizer about the DVTI camera project status starts at 2:25:00
- Sunday afternoon
     
February 8, 2022:   What a great sensation! For the first time, a stellar occultation caused by a nucleus of a comet was recorded! We congratulate warmly to our SOTAS members Stefano Sposetti, Alberto Ossola and Luca Buzzi! Well done guys!

The facts: Observed from Monte Ceneri and Muzzano, the nucleus of the comet 28/P Neujmin (18.3 mag, diam. about 21 km) occulted the star UCAC4 638-016921 (11.9 mag) and extincted its light for 1.76 resp. 1.28 sec.
Have a look to the report,  lightcurve,  target star,  video,  chord and the contribution in the Journal JOA (see page 10).
     
August 27/29, 2021:   This year, the 40th European Symposium on Occultation Projects (ESOP) took place at Białystok, Poland.
Follow to the Lectures.
  
For the Swiss contribution of Andreas Schweizer/Stefan Meister about the progress of the DVTI Cam Project, please forward to the time 00:28:30.
     
August 29/30, 2020:   This year, the 39th European Symposium on Occultation Projects (ESOP) took place online as a video conference. On average, over 100 participants were online. Besides participants from the EU, participants from Japan, Australia, Thailand, Turkey, Switzerland, UK, USA, Argentina and Brazil were registered. Many presentations and all live recordings including discussion can be viewed here.
     
July 31, 2020:   The 2020 IOTA Annual Meeting was held as a virtual session on July 25/26. During these two days, about 27 lectures were presented. Also the DVTI Camera Project of Andreas Schweizer and Stefan Meister was mentioned in a honorable manner.
Please follow the links for the agenda, protocol and video lectures.
     
Dezember 20, 2019:   New archieve initiated: This website includes all reports, lightcurves and videos of stellar occultations, observed by SOTAS members. The observed events are sorted by year, then by date.
     
September 10, 2019:   New available in agenda: Occultation Calendar, especially for Switzerland, by Stefan Meister/SOTAS.
     
30/8 - 1/9 2019:   38th European Symposium on Occultation Projects (ESOP) at the famous Paris Observatory. From Switerland, five SOTAS members participated to this highly interesting event. In the historic Cassini Hall, Andreas Schweizer and Stefan Meister presented the Digital Video Time Inserter (DVTI) Camera Project.
     
February 05, 2019:   The occultation of the bright star named Rasalasad borealis (my Leonis, 3.4 mag) by the small 15 km asteroid (34339) 2000 QH218 should be very impressive: the expected magnitude drop was 14.0 mag! The shadow of the star was crossing Switzerland from East to the West. Unfortunately, several participating observatories were blocked by snow or stucked in the fog! That's why Stefan Meister moved the mobile equipment to the Hulftegg (950 m/msl) for observing the event. Although the observing place was located only 2.6 km north off the center line, the event was observed as a missed event.
More information and impressive pictures taken during this cold night you will find on the VdS forum or here:
                            Report
     
December 20, 2018:   A new tool for the calculation of the combined brightness of two astronomical objects, standing close to each other, was created. If the apparent brightness of the two bodies are known, the excel sheet calculates the combined brightness and, more important, the drop of the brightness during the occultational event. The tool can be downloaded from here.
     
October 27, 2018:   The first meeting of the working group SOTAS was held in the Liceo cantonale in Bellinzona. Totally 16 "Occultazionisti" exchanged their experiences and discussed the coming projects. The successful event was very motivating for all participants.
Protocol,   Digital VTI,   Prepointing,   History,   1st observation in CH,   ESOP37-Review,   ESOP37-Lectures
     
May 13, 2018:   New: The Swiss Occultation Numbers, a monthly statistic about the observing activities of SOTAS members, was launched.
     
April 21, 2018:   Great success for SOTAS members: At 00:31 UT, the shadow of (130) Elektra, a 180 km asteroid, crossed Europe with center line directly along Switzerland. After good preparation works (workshop) and thanks to brillant weather conditions along the whole path, totally 9 (nine!) SOTAS stations recorded the disappearance and reappearance of the light of a 11.6 mag star. Eric Frappa (Euraster) arranged the chords and simulated the suitable model of the asteroid. Well done guys!
See the observations in detail...
     
Nov. 6, 2017:   Grazing occultation of Aldebaran by the moon: Between 03:14 and 03:18 UT, the star Aldebaran (alpha Tauri) was occulted in a grazing pattern caused by the limb profile of the moon. The observing path of this spectacular event passed Eglisau, a small town North of Switzerland. Stefan Meister prepared and organized an excellent observing campaign. Unfortunately, and once more, sky was clouded out during the interesting moments.
     
Oct. 5, 2017:   Star occultation by Triton: After an extra workshop and numerous previous successful tests, we all felt ready for the rare occultation event. Unfortunately, the weather was clouded out, stormy and/or rainy all over Switzerland exactly during the occultation event. Only one station reported an observation!
Summary and what we expected to see! Results
     
Sept. 18, 2017:   SOTAS has got a forum! Discuss your projects and stay informed. Register for automatic messages.
Special thanks to SAG for hosting the forum.
     
Sept. 16, 2017:   Meeting with workshop at the Observatory Bülach, considering the technics of recording and video time inserter. Goal: The participants are ready to record the occultation by Triton on Oct. 5, 2017.
Protocol  Script
     
June 2, 2017:   "3 - 2 - 1 - lift off" for the new working group! Let's occult!