David A. Kenyon
Professor of Astronomy,
Rocklin, CA. 95677
Wayne T. Watson
And James Clerk Maxwell Observatory
A fireball (or bolide) is another
name for a very bright meteor due to atmospheric entry of space debris, both
natural and man-made. This paper will discuss the technology, methods and
results from an “All-Sky” video camera and custom electronics to record
fireball events that occur over
The data was captured with Sandia Fireball Network cameras.
These systems are operated by the Sierra College Astronomy Dept. and a private
The systems are video cameras which have a 180o field of view. There is a custom signal processor and memory system, called the Sentinel system, which buffers a few seconds of continuous sky video. The processor compares each video frame to the previous, and when it detects an event (fireball), a few seconds of video (before and after the event) are sent to a host UNIX system. Only data relevant to motion is downloaded to the computer.
The system provides a method of recording and study for meteor shower activity. Second, all events captured by both cameras provide the potential to compute the pre-earth-encounter orbit, but also to estimate the impact corridor of any meteorites the fireball might have produced.
Our experience thus far shows that they occur about once a day and a very bright one every few weeks. The cameras began regular operation around mid-April 2004. To date, no fragments have been recovered from detected events.
A fireball (or bolide) is another name for a very bright meteor due to atmospheric entry of space debris, both natural (meteoroid) and man-made.
Sandia National Labs in
There are 21 Canadian sites and 22
Figure 1. The Fireball Network
The most active programs are coordinated by Chris Peterson, who manages several sites in Colorado; Ed Majden, with his camera and a large network of observers in British Columbia; and Jim Gamble, a collection of observers in El Paseo.
Our experience thus far shows that fireballs occur about once a day and a very bright one every few weeks. Our program began regular operation around mid-April 2004. It is an automated system which operates from just before dusk to just after dawn.
2. Program Goals
Primarily, the system
provides a method of recording and study for meteor shower activity. This
program supports the Fireball Network as well as providing is a focal point for
meteor observations in the north western
Second, all events captured by both cameras provide the potential to compute the pre-earth-encounter orbit, as well as to estimate the impact corridor of any meteorites the fireball might have produced. This could result in the recovery of fragments from the falling object.
Since the beginning of the
program over a year ago, we have received observer support and interest
3. The Hardware
The video system used is a Sandia National Laboratory Sentinel Video System. The system consists of a video camera with a wide field of view. The camera and lens are mounted pointed to the sky in a weather protected acrylic dome. This unit is secured to a stable platform with a clear view of the sky (see figure 1.). The system yields an “All-Sky” imaging system which has a 180o field of view.
Figure 2. All-Sky camera and protective dome.
The camera is connected (weather protected) to the Sentinel Video System (custom signal processor and memory) which buffers six seconds of continuous video of the sky. The processor compares each video frame to the previous frame and when it detects an event (fireball), six seconds of video (centered on the event) is sent to a host PC based Linux system.
The signal processor is connected to the PC via the printer parallel port. This port provides command and control interface as well as data transfer functionality.
There are two systems at different sites involved with this
program. The first camera is located on top of the
The second camera is located at a private observatory in
39° 15' 7" N of latitude and 121° 2' 32" W longitude with an elevation of 823 meters in the Sierra foothills.
4. The Software
The Sentinel detection software is written in C and operates under the RT (realtime) Linux OS, which permits Sentinel to field events immediately and adjust data collection and related. Realtime OS’s are widely used in science and industry to optimize data collection under quickly varying conditions.
Clocks at both sites are independent, and provide time stamps for the data. The Rocklin site provides better accuracy and is used for analysis when both sites observe the same event.
The software provided with the Sentinel Video
System includes control software (sentuser2) which
is used to control the hardware. The software
includes commands to initialize the system, set
detection thresholds, masks to block problem areas
of the sky and program on and off times.
Also provided with the system is a viewer
(sdisplay) to examine the images and video clips
downloaded from the hardware. There are also
support programs to generate xxx.jpg [jpg image
format] images and xxx.mov [Quicktime video
formatted files] of detected events.
5. Data Collection
When an event is detected, an all-sky image is captured at 640 x 480 pixels of resolution and downloaded to the host. Superimposed on this background image is a 125 x 125 pixel video clip centered on the event (see figure 5). This image and video are viewable with the sdisplay program.
Figure 5. All-Sky image and video overlay
To accurately identify the path of the fireball event on the celestial sphere, an autoexpose feature is available on the Sentinel System. This feature periodically collects a long exposure image of the sky which yields the brighter stars for orientation of image and video clip (see figure 6).
Figure 6. Autoexposure image.
useful data occurs whe
Figure 7. A simultaneously detected event
The coverage area for the program’s cameras is depicted in figure 8.
Figure 8. Program coverage map.
6. Preliminary Results
of the 2004 events detected ca
Table 1: Counts for Both Sites
Figure 8. June ‘04 simultaneous detection
two images and a calibration of the sky at each site, he was able to produce a
3-D track. It indicated a potential impact site southeast of
program is being recognized as a primary contact for fireball observers in
western U.S. Observers from
The images below are some of the brighter fireballs detected by this program.
Figure 9. Event at
Figure 10. Event at 09/21/0401:58:24.
Figure 11. Event at
videos of detected events ca
7. Table of Detected Events
Table 1. Sample Excel table.
The Program has made very
good progress in establishing the two sites for fireball and meteor monitoring.
We have been able to exchange informatio
For the future, we will continue to expand the program capabilities by improving upon the software and tool set which support the systems. Specific areas of focus will be: image stacking, operational ease, improve star overlays on images, and early estimates of tracks from dual observations of an event are some of the possibilities.
We would like to acknowledge the support provided by Richard Spalding
and Joseph Chevez
with the Sentinel hardware and software.
Also, the support of
Video Sentinel Users Manual. J.C. Chaves, Sandia National Laboratories