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Ursa Astronomical Association

Perseids - 18.8.2015 at 00.12 Espoo & Vantaa Observation number 42609

Visibility IV / V

Janne Sievinen, Pentti Arpalahti, Ursa (Helsinki)

In the autumn of 2015, during the Perseidi swarm, we accidentally shot the same meteor with Pentti Arpalahti at a distance of about 12 kilometers from each other in Paloheinä, Vantaa, and Röylä, Espoo. Looking at the images, attention was drawn to the clearly observable parallax, which provided an opportunity to try to reconstruct the orbit of the meteor.

The azimuth of the observed ignition and extinction points of the meteor and the determination of the altitude coordinates for each observation site were straightforward using star map software because the observation time and the coordinates of the observation sites were accurately known. The site-specific ignition and extinction direction vectors, as well as the observation plane sectors tensed between them, could then be drawn with CAD software into a 3D model corresponding to the geometry of the observation situation. The curvature of the globe between the observation sites was not modeled because its magnitude for the overall accuracy of the target kilometer range remained small.

The advantage of using CAD software is that the meteor trajectory can be easily determined by graphically searching for the intersection of the observation sector planes, thus avoiding more demanding mathematical observations of spherical and planar geometry, which of course makes it possible to solve analytical equations for the trajectory.

The reconstruction was performed with Autodesk Fusion360 software, and verified by replication with MatLab. As a result of the analysis, the following parameters were determined:

- ignition height 122 km

- stepping height 95 km

- the length of the visible flight path is 47 km

- the angle of the flight path to the ground 30 degrees from the horizon

- the direction of flight is 232 degrees southwest

- flash point above Savio in Vantaa

- extinction point above Vitträsk in Kirkkonummi

The results are consistent with the parameters commonly known to the Persides, so one can assume that the reconstruction is in the right direction.

As a note, due to the exposures used, the gradual ignition of the meteor in the image taken in Paloheinä was determined to be slightly earlier than in Röylä. For this reason, the edges of the observation plane sectors do not intersect with each other in the ignition region. The direction of extinction, in turn, was determined from the images at almost exactly the same point in the sky. The ambiguity associated with the determination of the flash point was, of course, only parallel to the direction of flight of the meteor, so it has no effect on the directional results of the reconstruction and the location of the extinction point.

3D rotation video here:

Additional information
  • Observation target
    • Meteor image
  • Name of the observation target
    • Perseidit
    • Näyttävä
Comments: 5 pcs
Emma Bruus - 14.9.2015 at 12.11 Report this

Todella ansiokas havainto ja hienoa tutkimusta!

Juha Ojanperä - 14.9.2015 at 13.09 Report this

Todella mahtavaa työtä, nostan hattua! Tämäntyyppisiä havaintoja, analyysiä ja tutkimusta toivoisi Taivaanvahdissa näkevän useamminkin!

Tapio Lahtinen - 14.9.2015 at 16.31 Report this

Toden totta, ansiokas havainto ja mallinnus.

Markku Siljama - 14.9.2015 at 22.10 Report this

Yksi parhaista koskaan Taivaanvahdissa näkemistäni havainnoista.Hienoa työtä!

Antti Rinne - 15.9.2015 at 08.09 Report this

Hyvää työtä!

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