Condign volumes 1 to 3

Read from the scan by GLM-OCR; expect the odd misread word.

# UNCLASSIFIED

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The plots are for objects 'flying' at constant altitudes. If an object is either climbing or diving then a different calculation is needed.

## INTERPRETATION

6 Figure 2 (for both endo-and-exoatmospheric targets) enables a target speed to be approximated, based on witness assessments of angle traversed (az or el), range and time of observation:

$$
v = \frac {R \varphi}{t}
$$

where $ \varphi = $ Angle traversed (radians) = Deg/57.29

R = Witness estimate of target range

t = Witness estimate of duration of sighting

7. The same approximation applies to space-based objects. In this case it is assumed that exo-atmospheric objects can be at any altitude above the earth.

8. It is important to note that the method used is based on the assumption that moving objects travel tangentially through the estimated angle, with respect to the observer's position. Any movement at other angles with respect to the observer would increase the track-length flown and thus, in a given time, increase the object's velocity.

## EXO-ATMOSPHERIC OBJECTS

9. Meteorites Diving objects (e.g. often shown to be meteorites/meteors) are frequently reported. These are high velocity ionised trails caused by meteor-body friction with air molecules, which then ionises; usually with a fiery tail/trail, lasting only a few seconds. RF reflection from trails (utilised for scatter HF communications purposes), occurs in the (approximate) 30 to 120MHz range. Meteor-trail duration is measured in hundreds of milliseconds. Two categories describe the rate

at which meteors strike the earth's atmosphere. The periodic group (known as meteor 'showers'), which have a yearly cycle and the sporadic group which are, though more random, occur year-round. In the context of UAP sightings:

'Showers' occur for periods from hours to days at a rate of the order 20 to 50 per hour. These are often present, though not necessarily visible, due to the interference of moonlight. The forthcoming occurrence of showers can be predicted, because both the earth's (and the meteor stream's orbits) are known - hence the intersection can be calculated. What is not known is the shower density. There is a shower density cycle repeating every 33 years. There is no connection between meteorite activity and sun spots or solar flares.

- 'Sporadics' exhibit a Poisson distribution but with a diurnal variation.

- In addition to the familiar largest fireball-producing meteors there are tiny grains not visible to the human observer. Radio and radar methods allow the latter to be detected. As the meteorite rate may have a bearing on the production and presence of some types of 'UAP', attempts will be made to correlate meteorite density against the trend of UAP reports.

10. This latter condition reflects the fact that at dawn (local time) a meteor will cut the longest path in the atmosphere, while at midday the meteor will appear to strike the atmosphere vertically. As the size of meteors varies between smaller than a grain of sand to those that survive and impact the earth's surface, the initial mass varies inversely with its probability of arrival. Consequently, smaller meteors make up a significant proportion of all meteors arriving and are not large enough to be seen visually.