ALL SKY CAMERA CLOUD SENSOR and METEOR DETECTOR

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<strong>ALL</strong> <strong>SKY</strong> <strong>CAMERA</strong><br />

<strong>CLOUD</strong> <strong>SENSOR</strong> <strong>and</strong><br />

<strong>METEOR</strong> <strong>DETECTOR</strong><br />

SBIG has developed a new camera system<br />

designed to watch the skies all night <strong>and</strong> log<br />

any images with moving objects in them. This<br />

new version of our all sky camera sacrifices<br />

some field of view for sensitivity, <strong>and</strong> as a<br />

result can detect satellites down to 4th<br />

magnitude, <strong>and</strong> several meteors a night during<br />

non-meteor shower periods. The field of view<br />

is still a very respectable 90 x 140 degrees.<br />

The is 0.185 degrees per pixel.<br />

All Sky / Meteor / Cloud Camera<br />

The image at right shows the camera in its weatherproof housing. The camera is an uncooled, shutterless<br />

version of the ST-402ME mated to a 2.6 mm focal length F/1.6 CS- mount lens. The box also contains a<br />

USB extender, <strong>and</strong> a 12 VDC power supply for the camera. The window in the top of the box is an RG-<br />

630 red filter designed to dramatically reduce light pollution (<strong>and</strong> light from the moon) for users in brighter<br />

sites. The window is heated to prevent condensation. The USB extender allows operation up to 150 feet<br />

(50 meters) from the controlling PC.<br />

A meteor trail is seen as a streak near the<br />

milky way in the center of the frame. Very<br />

faint clouds are also detected on the left.<br />

The sample picture below shows a<br />

typical image from this unit where<br />

a meteor was captured. The<br />

camera was running with 10<br />

second exposure times.<br />

REMOVE/SOFT, if desired. SBIG<br />

has written special software to<br />

automatically take images all night,<br />

compare each image with the<br />

previous one, <strong>and</strong> scan the image<br />

for linear features typical of a<br />

meteor or satellite.<br />

The software uses a Hough<br />

transform to find linear features,<br />

plus other tests. Each image with<br />

something in it is saved for later<br />

inspection. A filter is available to<br />

cut down on false alarms due to<br />

plane traffic, if you live near an<br />

airport. The software also allows the images to be easily viewed later to eliminate false alarms.Compared<br />

to our previous All Sky camera, this camera does not cover the entire sky, however, with the previous allsky<br />

camera covering a full hemisphere often meant users would have a streetlight or window in the field of<br />

view, which corrupted the image annoyingly. Also, this data is intended to be useful for triangulating the<br />

height of the meteor, which is difficult near the horizon.<br />

The system works surprising well when the moon is full, with little loss of sensitivity. It is sensitive to<br />

linear clouds on such nights, such as cirrus or contrails. A side use of this system is therefore watching for

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high clouds at night. The unit<br />

can definitely allow one to see<br />

if clouds are present overhead<br />

at night when they are not<br />

visually detectable. The<br />

detection is easier if you live<br />

in an area with modest light<br />

pollution since it lights the<br />

clouds up. If your main<br />

interest is in detecting faint<br />

clouds overhead we can ship<br />

the camera with a clear<br />

window. The picture below<br />

shows an image taken with the<br />

camera of some clouds at night<br />

illuminated by light pollution.<br />

These clouds were fainter than<br />

the Milky Way visually, <strong>and</strong><br />

not easy to see.<br />

Clouds moving in during the night. These could not be<br />

easily seen visually.<br />

We have found that running<br />

the system on every clear night is very interesting, particularly knowing that if something significant<br />

happens you will have a record of it. We have caught some fireballs with a prototype version of this unit.<br />

Iridium flashes <strong>and</strong> satellites are commonly seen. The unit is most useful when a sister camera within a<br />

few miles can be set up so triangulation is possible. Events occruing in the Earth's atmosphere as <strong>and</strong> the<br />

altitude of earth orbiting satellites can be measured to within a few percent accuracy depending on how far<br />

apart the systems are located. Generally 4 to 10 miles separation is about right for satellites as the cropped<br />

test images below demonstrate. Two Meteor Cameras being operated 7 km (4.36 miles) apart captured the<br />

same Cosmos 1437 Booster. Based on the separation of the observing sites, the Booster's position against<br />

the background stars appears to shift (parallax). By triangulation, it was determined that the Booster was<br />

approximately 150 miles away at the time.<br />

Meteor Cam 1 Meteor Cam 2<br />

< < Separation Between Cameras Approximately 7 km >>