2 Video record of the bolide

The video record was an exceptional opportunity to carry out a detailed study of the event, much better opportunity than if only visual sightings would be available. A group of University students had been celebrating at an evening party on an open terrace at the top of a rather high building ($\approx 30$ m above street level) located near the center of Santiago de Compostela. This terrace is oriented to the East (the bolide moved from SE to N) and the cameraman, J.A.Quiroga just faced the bolide when it started to be enormously bright. He has been recording the dancing party members, but he immediately decided to follow-up the bright sky phenomenon. Quickly and smoothly he moved the camera up and left to the object, and followed its motion with a great care and ability until the bolide light became definitely extinct. Thus he obtained an exceptionally valuable record of the bolide and its fragmentation. The record owners A.Salazar, D.Neira, and J.A.Quiroga transferred all copyrights of video recorded images to the authors of the present study. One of the frames is presented in Fig. 1 and except the main body shows also 3 larger fragments. The entire available information from video camera is included in this paper in a form of CD ROM copy of the digitized video tape (see Appendix).

  

Figure 1: Video frame No.117 (MET117) shows the bolide appearance at the relative time 4.68 s with individual fragments 5, 6, and 7 well separated from the main body

2.1 Compact disk copy of digitized video frames

With the aim to extract maximal information from video tape, we proceeded to its digitization dividing all record to 191 separate frames recorded on the compact disk (CD) with the following characteristics:

1.

Duration: 7.6 s.

2.

Resolution on GIF and BMP files: $720\times 576$ pixels.

3.

Resolution on AVI files: $480\times360$ pixels.

4.

Number of frames: 191 (digitized by 25 frames/s).

5.

Digitization code Microsoft Video 1.

6.

CD space occupied 34 MB.

Since these frames are the essential part of the present work, we consider mandatory to include CD into our paper as an Appendix. Our measurements for the positional reduction of this paper were performed using GIF files.

1.

Directory GIFS contains 191 files ($\equiv$frames) in GIF format.

2.

Directory BMPS contains the same frames in BMP format.

3.

Directory ANIM contains digitized video in MPG format (MPEG frames) as well as AVI-formated files; they can be reproduced on any PC with Microsoft Windows.

2.2 Fiducial objects for calibration

Fortunately, the apparent position of the object during the last part of the recording was low enough for some terrestrial objects to be recorded simultaneously with the bolide. Thus we can make use of these objects as fiducial points for computing horizontal coordinates (azimuth and elevation). Chimneys and TV aerials of some close buildings as well as towers of the famous Cathedral of Santiago de Compostela (the bolide finished the apparent trajectory close to the Cathedral) constitute the fundamental reference points when we assigned the horizontal coordinates to the bolide image at different frames. Once reference points were recognized and established on individual frames, we proceeded to measurements of azimuths and elevations of 10 points using a theodolite installed exactly at the position of the cameraman. Also high quality photographs of the surroundings were taken from the position of the cameraman. They were used for identifying objects on the video frames and also for deriving coordinates of some additional fiducial points.