# Fire Correction Circle

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In a military context, especially in [indirect fire](/source/Indirect_fire) by the Finnish artillery of the [Continuation War](/source/Continuation_War), the **Fire Correction Circle** (Finnish: *korjausympyrä*) or (Fire) Correction Converter Dial (Finnish: *korjausmuunnin*) is a fully mechanical auxiliary device which was constructed of [plywood](/source/Plywood) and transparent plastic and which used to be used to calculate [targeting values](/source/Targeting_value) for [indirect fire](/source/Indirect_fire) and [mortars](/source/Mortar_(weapon)). By using a Correction Circle the [artillery observer](/source/Artillery_observer) is able to report the necessary fire corrections to the unit firing without knowing exactly where the unit is firing from. This is achieved by having the artillery observer report targets' coordinates (distance and [azimuth](/source/Azimuth)) from his or her own position to the firing units, then report corrections (both lateral and distance-) in meters after a salvo. Each firing unit would make their own calculations for correction based on their own position, target's position, artillery observer's position as well as lateral- and distance corrections in meters provided by said observer, in theory allowing for an unlimited number of firing units to fire on a single target using the same target coordinates and corrections reported by a single artillery observer. The system can and is also used to quickly switch between targets within the artillery observer's vision by simply reporting sufficiently large corrections.

As an example of this in use, during the [Battle of Tali-Ihantala](/source/Battle_of_Tali-Ihantala) [Finnish Army](/source/Finnish_Army) had 21 artillery battalions and one heavy battery, a total of 250 guns and mortars, focusing their fire on targets inside an area of 7 square kilometers, considered to be a world record at the time.[1]

## References

1. Koskimaa, Matti (1993). *Veitsenterällä : vetäytyminen Länsi-Kannakselta ja Talin-Ihantalan suurtaistelu kesällä 1944*. WSOY. ISBN 951-0-18811-5.

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Adapted from the Wikipedia article [Fire Correction Circle](https://en.wikipedia.org/wiki/Fire_Correction_Circle) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Fire_Correction_Circle?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.