Sandia Fireball Movies from Nevada City, CA

(Recent Images at bottom, scroll ... I'm restoring this site after an outage caused by a change of ISP. Most of this page is introductory about the Sentinel Fireball Network. I've add some 2007 observations at the bottom until I create a completely different page for 2007 data.)

Organization of Page

Background
Coverage
The Camera
Meteors and Fireballs
Images: Videos, Composites and Radio

General Orientation
Video Composites
Videos
Radio Observations

Miscellaneous Images and Data from May and June 2004
Recent Images from 2005

Background

Very early this year my partner, Dave Kenyon of Sierra College, in camera meteor observations and I received our equipment from The Sandia Fireball Network effort supported by Sandia National Laboratory in Albquerque, New Mexico, and spearheaded by Dr. Richard Spalding. Joseph Chavez wrote the realtime Linux application that controls the camera. After several months of activity to get the hardware and software properly set up, we began both operations in about April. We installed an All Sky, 180 degree view of the sky, black and white digital video cameras with the Sentinel software and hardware provided by Sandia. Our cameras are in operation pretty much every day from around sunset to sunrise. I have my camera in Nevada City, and my partner has his about 30 miles south of here in Rocklin. We've been catching images and recording them on our local computers, and Dave has a meteor gallery of his images plus any of mine that coincide closely in time.

Coverage

The map below shows our general operational coverage. The radii draw about the two camera locations are 200 miles in diameter. A meteor burning at 60 miles above the circumference would appear about 15 degrees over our respective horizons. Note that this coverage extends over the Oregon/California border, and well into Nevada. Los Angeles is about 380 miles from Nevada City, and would appear a few degrees above my horizon if at 60 miles above LA. .

For a bit more information on coverage, see the table below. The first five points are at 10, 20, 30, 40 and 60 miles

The Camera

Video camera at top of housing

Camera housing, Sentinel intermediate storage device

Innards: heater, fan (both thermostatically controlled), connectors, etc

.
Sentinel box, miscellaneous connectors.

Camera close to final installation on a 10 foot pole.

Meteors and Fireballs

A fireball is another name for a very bright meteor. My experience thus far shows that they occur once every few weeks. The camera began regular operation around mid-April 2004 working from around just before dusk to just after dawn. At some point, we will likely operate it 24 hours a day. Rarely, fireballs are visible in the day time, but, if one is imaged then, well ...!.

Sometimes it is not obvious that a streaking object in the sky is a meteor. A close fast moving plane, for example, can look like a meteor trail. However, there is usually a characteristic that betrays such objects. In the case of a plane, its blinking lights may give it away. I share data with a partner some distance from here, and a simultaneous sighting helps confirm a sighting. If equipment is down or weather interferes, it is not always possible to get such confirmations. It then becomes necessary to look for clues that reveal the object as something other than a meteor. For example, a very slow speed, blinking, or erratic motion. A bright Venus low in the sky and behind waving tree branches will trigger the camera producing erratic images. There are sources on the web that can sometimes provide information from other meteor observers about sightings.

Images: Videos, Composites and Radio

General Orientation

To see extra details in the videos and other images you may have to adjust the contrast and brightness of your monitor. The following image is a day time image that will give you some perspective of what the sky line looks like. The view is all sky, that is, it images everything from the horizon to the zenith (overhead). Top is north and east is to the left, The view is though you were lying on your back with your head pointed north. The reason for the rotated image is that I do not have a current day time image, so this one is rotated to the current view. The sun appears to be setting in the west above the house. Note trees along the sky line, and an observatory towards the east. (Note: In September, the camera was moved to another location about 100 feet north of the images taken here to open more sky.)

The next several are short duration shots, less than 1/2 second each. It takes a great deal of image stacking to bring out dimmer stars with this arrangement.

Not much out there? Maybe. The two lights on the left are from a few homes about 1000 feet away. The other light is Venus, almost due south of the camera.

Pretty much the same view but a little closer to dusk. Venus and one house light. Now you can see our house stretched out the right lower corner. Note the two lights that look like wings are a window in the garage with the curtain pulled up on each end. Note two ponderosas near end of house on right.

This is two stacked images with a little image processing. You can see a light smeared across the door area (120 degrees, clockwise from north at the top) of the nearby building, Venus (145) over the garage, the observatory (350), houses a 1000 feet away (230), and likely Orion stars and Sirius (230) above the distant houses.

Cloudy sky around 4 p.m.
The image shown is of a halo that appeared around the moon Saturday night the Feb. 28, 2004. Such halos are not infrequent, and are caused by ice crystals in the atmosphere. The halo is 22 degrees from the moon. The image was taken with a fish-eye lens of the entire sky from horizon to horizon with a sensitive video camera. Although the moon was only half full, the image was intense enough to smear out as a circle. A nearby house, manaznita, tall trees, lights from distant homes, and a nearby building appear along the around the edge of the photo. Despite the general cloudiness, some bright stars can be seen in the southwest portion of the image.

Moon Halo

Video Composites

The next image is a composite image made from successive video frames.

June 26, 2004 (Time: 23:31:29 PDT/06:31 UT, 27th)
(Note: June 26-27 observations are tagged with times about 3 minutes too fast.)

We discovered that both of our cameras had taken an image of this fireball. Some weeks later Robert Matson with SAIC in S. Calif. was able to use the two images to find a potential fall location southeast of Sacramento. Some other work on his part found that is was more likely a meteor fall than a rocket stage fall.

Video

The URL contains a movie taken by my Sandia Fireball Network black and white video camera. You will need an Apple Quicktime plugin viewer to see them. Color images are false color images taken to enhance details. Still images are composites of successive video frames unless noted otherwise. All times are Pacific time. Add 8 hours for UT.

The movie of the above can be found by clicking here (/Meteors/v20040626_233129.88b.mov). [1,000K]

Radio Observations

Radio confirmation.

Miscellaneous Images and Data from May and June 2004

This fireball is high in the sky and appears to be coming downward rather steeply. It appears as a small dot and then its size increases rapidly. I was able to confirm that this was a fireball by simultaneous radio observations described below. The sun rises in one hour after this point, and clouds in the east appear to be illuminated by approaching dawn. The moon is visible over the eastern horizon. Although it is not full, the camera's low resolution makes it appear as a cricle.

This is a (strong) radio echo of the meteor caught simultaneously to my video image by Norm Davis in Shingle Springs, CA about 30 miles east Sacramento, and 50 miles south of my location. This is excellent confirmation that my observation was a meteor. Such signals are often produced by an FM radio or TV signal reflecting off a meteor trail towards a multi-band (radio & TV) receiver, in this case, in Shingle Springs. Time runs across the graph, and frequency (kH) along the left edge. Computer signal processing of the resulting noise produced by the meteor's interference with the TV or radio signal produces the diverse distorted blips and waves seen in the graph. The difference in the peak seen here at 04:54 and my observation at 04:47 is because our clocks were not synchronized. The degree of separation is very close to the differences in our clocks on that date.

After having one camera disabled for some time, we are now back in operation. Below are two meteor event images. One for November 16 and the other for the 17th. An image from each site, separated by 30 miles, is shown. The bright object is the moon. The squares are artifacts from combining images from each frame. Note the images at each site do not intersect one another when they are superposed on the other even though the cameras are identical and aligned on north (at the top, left is east). This may seem odd, but suppose the meteor were over the zenith at one site, and 30 miles above it. Then from the other site 30 miles away, it would appear at about 45 degrees altitude.

Movies of these events can be found at the Sierra College Astronomy Dept. web site. They should be available some time on November 18th.

Brilliant fireball that passed over Shingle Springs, CA observed from Nevada City, CA.

Composite from many video frames. The skies here are so dark that the horizon is almost invisible except where the fireball lit up the area. North is up, and left is east. A comparitive shot below shows a meteor with the horizon emphasized.

The image above is a composite from many video frames of a brilliant fireball that disappeared over the SE horizon at 00:05 hours on Saturday morning the 11th. It was noted by several observers as it went overhead in a lightly populated area, Shingle Springs, of the Sierra foothills about 60 miles from here. My guess is that what appeared to be a burst is really a distortion from clouds near the horizon as it proceeded to go below the horizon. Two of us took images and its trajectory will likely be analyzed soon. It's quite possible that chunks fell to earth. There was some confusion on this point by the other observer on details he learned later from eyewitness accounts that were somewhat ambiguous. The eyewitness reports will likely be re-examined as the trajectory analysis proceeds.

My sky is so dark the horizon is not evident until the meteor was close to the horizon, and the composite image provides contrast.

The meteor was not from the Perseid radiant point.

My house is stretched out along the right side and ends about at the tall ponderosa, west.