North

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When north- facing, a map , a plan or an aerial photo is aligned in such a way that the directions shown on it (e.g. the course of roads or the bearing directions between two objects) run parallel to the corresponding directions in the terrain . The map and terrain are then oriented in the same way , in particular the north side of the map points north. The north makes it easier to compare the map and the terrain; it is also a prerequisite for some map work with the compass .

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To find out how to mount a telescope to the north, see the Astronomy section .

Northing a map

Rough north without a compass

The fastest and easiest method for roughly northing a map is to compare it directly with the surrounding terrain. Your own location on the map must be known with sufficient accuracy. The map is then rotated until the bearing direction from the location to a distant object on the map (e.g. hut, crossroads, mountain peak) matches the bearing direction in the area. Of course, this is only possible with sufficient visibility. Sometimes nearby terrain features can also be used: If you are on a path, you turn the map until the section of the path running through the location on the map is parallel to the real path. This is also possible with other line-like terrain features, e.g. B. with forest edges, brooks, etc. If you are on a slope, the contour lines of the map must run perpendicular to the fall line of the terrain.

Rough north with a compass

Rough north of a card on the edge

When northing with the help of a compass, no distance vision is required and your own location does not have to be known. You turn the map until the side edge of the map sheet, the side map frame or the grid lines running in north-south direction (if any) are parallel to the magnetic needle of the compass, with the north end of the magnetic needle pointing to the north side of the map. Alternatively, the place names on the map that usually run in an east-west direction can be used, which must be perpendicular to the magnetic needle after the north-facing position.

These compass methods ignore the difference between true north, grid north, and magnetic north. In the German-speaking area, these differences are only a few degrees, so that the rough northing described is sufficient for most orientation tasks. The procedures described below should be used for higher accuracy requirements or in areas with greater declination.

More precise north with a compass


  • Magnetic declination: The local magnetic north can differ significantly from true north. The magnetic declination for 2010 is shown.

  • Meridian convergence:
    The meridians of the geographic network (red) are usually inclined to the lines of the map grid (gray).

In this case, the following north directions must be distinguished:

  • Geographic north, i.e. the direction to the geographic North Pole . The longitudes ( meridians ) of the earth run in a geographical north-south direction.
  • Grid north, i.e. the direction of the map grid lines (if any). While all longitudes run towards the North Pole, that is to say approach one another (“converge”), the grid lines run parallel to one another according to their definition. In a meridian strip , therefore, at most one grid line can coincide with a longitude circle . The other longitudes and grid lines intersect at angles which increase with the distance from the equator and with the distance from the central meridian of the meridian strip.
  • Magnetic north, i.e. the local direction of the field lines of the earth's magnetic field . The compass magnetic needle points in magnetic north.

These north directions are usually not identical:

  • The difference between magnetic north and true north is known as magnetic declination . It is currently only about 0.5 ° to 3.5 ° East in German-speaking countries, but reaches z. B. in Canada, USA, South Africa and New Zealand sometimes 20 ° or more and can then no longer be neglected.
  • The difference between grid north and geographically north is called meridian convergence . It has the value zero on the central meridian of a meridian strip and on the equator and increases towards the edges of the strip and towards the poles - in the UTM grid up to a maximum of ± 3 ° and in the Gauß-Krüger grid up to a maximum of ± 1.5 °.
  • The difference between magnetic north and grid north is called the needle deviation . It corresponds to the difference in declination minus meridian convergence.

The official topographic maps in Germany and Austria are degree department maps, i. H. the lateral boundaries of the map field are meridian lines. These maps are therefore aligned to the north if the map frame is oriented to true north. In many maps, meridian lines are also marked on the edge of the map, but not drawn through; if necessary, the user can draw them in with a ruler and use them to align.

In Switzerland, the map edges of the topographic maps coincide with grid lines. These cards are aligned to the north when the card frame is aligned to the north of the grid. In many modern maps, map grids are also printed directly into the map field and can be used for northing. Geodetic map grids are not to be confused with the search grids printed on some maps (“Hotel Müller see B-7”), which have no defined relationship to the north direction.

A compass is used as a tool for aligning the map to geographic north or grid north. However, this always points to magnetic north, so that the declination (if meridian lines are to be aligned to geographic north) or the needle deviation (if grid lines are to be aligned to grid north) must be applied as a correction. The easiest way to correct this is that the compass needle is not aligned with the north mark of the compass socket, but in such a way that it shows the relevant declination or needle deviation on the graduation of the socket. Topographic maps usually contain information on magnetic declination or needle deviation for the area shown.

Typical map compass

A compass whose side is designed as a contact edge is particularly suitable for map work. Such a compass can be placed on a map line in a defined manner and can also be used as a protractor: If you turn the compass socket in relation to the housing so that e.g. B. the direction angle is 45 ° on the reading mark of the housing, then the contact edge forms an angle of 45 ° with the north-south marking of the can. If you then turn the entire compass so that the compass needle is parallel to the north-south marking of the can, the contact edge also forms an angle of 45 ° with the magnetic north direction (see the applications described below).

If you set the direction angle 0 ° at the reading mark, the north-south marking of the can and the contact edge are parallel to each other.

  • If you now turn the entire compass so that the north end of the needle on the graduation of the can shows the value of the declination , then the contact edge points in the direction of geographical north .
  • If you turn the entire compass so that the needle on the graduation shows the value of the needle deviation , the contact edge points towards the north of the grid .

To north a map, place the leading edge on a meridian or grid line on the map, depending on availability, and rotate map and compass together until the needle shows the declination or needle deviation value. A meridian line used for creation then points to geographic north, a grid line used for creation points to grid north. The orientation of the map now corresponds to the terrain within the compass accuracy.

Magnetic interference from equipment (ballpoint pen, watch, camera, other compass, vehicle, etc.) must of course be avoided. If necessary, local magnetic anomalies must be determined and corrected using test bearings with the compass.

Applications

From the map to the terrain

In order to determine the direction of march to be taken in the terrain from a map that is northerly, the map compass is placed on the map in such a way that its contact edge connects the location and the destination. The compass socket is then rotated so that its north-south marking is parallel to the magnetic needle. The contact edge of the housing and the north-south marking of the can now have the same angle to each other as the direction of march and the magnetic north direction.

The compass set in this way can be removed from the map; its contact edge (or a marching arrow attached parallel to the edge on the housing) points in the direction of march, as long as the north-south marking on the can is held parallel to the magnetic needle. It is not necessary here to actually read the march angle from the graduation, unless it is needed otherwise.

From the terrain to the map

In order to transfer a bearing direction from the terrain to the map (e.g. if a mountain peak is to be identified), the object in question is sighted with the compass (depending on its equipment via the rear sight and front sight or along the contact edge) and the compass socket is rotated that its north-south marking is parallel to the magnetic needle. The contact edge of the housing and the north-south marking of the socket now have the same angle to each other as the bearing direction in the field and the magnetic north direction.

With this setting, the compass is placed on the north-facing map so that the beginning of its contact edge is at your own location. The entire compass is rotated around this point as a fixed point until the north-south marking on the can is parallel to the magnetic needle. The direction of the landing edge on the map is now parallel to the bearing direction in the terrain and goes (within the compass accuracy) through the object to be identified on the map.

This procedure can also be used the other way round to determine your own location. To do this, you aim for an object in the area that can be identified on the map, this time place the end of the contact edge on the object on the map and turn the entire compass around this fixed point again until the north-south marking of the can is parallel to the magnetic needle. Your own location is on the line determined on the map. Repeating the bearing with another object (if possible at a 90 ° angle to the first bearing) provides a second position line; the location lies at the intersection of the two baseline lines.

Map work without northing

Taking angles from a map that is not aligned with the help of a transparent map compass.

Modern map compasses make it unnecessary to orient the map. They have a clear box with north-south lines printed on the underside. To get a marching or bearing angle from the map, place the compass with the edge along the target direction on the map and turn the can until its printed grid lines are parallel to the meridian or grid lines on the map visible through the can. The target direction is set on the compass with respect to geographic or grid north and can be transferred to the terrain. To do this, the entire compass taken from the map is rotated until the magnetic needle shows the declination or needle deviation on the graduation.

This method does not require a backing for the card. The map and compass do not have to be horizontal, so they can be held freely in the hand. The setting of the angle on the card is also independent of any magnetic interference, as the magnetic needle is not involved in this step. On the other hand, the direct reference to the terrain is lost, so that the risk of mix-ups increases.

South

The royal seat of Dresden lies in the south of the Elbe, the Neustadt in the north. For the cartographer, the (north-south) city with the dividing river is in the foreground. So he drew West upwards. The user read the exact points of the compass on the compass rose at the bottom right

Until the 19th century, map images were also oriented to the south ( south ) and were thus upside down according to today's view. However, an arrow drawn in, often in a compass rose , made it possible to align the map sheet with the cardinal points.

Southern maps are for example

Since at least until the 18th century the concept of the map maker was in the foreground, there are also map layers that point upwards in the west or east. Such types of easted or wested maps are preferably available for views where the local or regional consideration was of importance. For example, Schmitt's map is oriented from southwest Germany to France and therefore wests.

Sometimes southern maps are still in use. One example of this are Australian world maps. In Australia, the south corresponds exactly to the importance for weather and orientation that the north has in Europe. From an Australian point of view, north-facing world maps are actually upside down.

astronomy

In astronomy , northing is the correct alignment of an ( equatorial ) mount that carries an astronomical device - for example a telescope or an astro camera. The hour axis of the mount is directed as exactly as possible parallel to the earth axis , so that it points towards the celestial pole . For observers in the northern hemisphere of the earth, the celestial pole is always exactly in the north direction (geographically north, point of intersection of the earth's axis of rotation). In addition, setting the polar height is part of the north alignment of an astronomical mount . Northing is usually done with the help of a pole finder or with the Scheiner method (Einscheinern, Scheiner method ).

With exact alignment, the tracking on the mount precisely compensates for the apparent rotation of the sky (rotation of the earth) over time. Without precise alignment, observed objects slowly move out of the field of vision or longer exposed photos become line images.

Use of language

In colloquial language , the term "northing" or "northing someone" is used to mean "pointing the way" or "correcting someone". Since the time of National Socialism there has also been the term “ Gleichschaltung” . In the language of the soldiers, the term means the knocking over (or upside down) of a locker by lower superiors or comrades in order to increase the motivation of the regular clearing.

Individual evidence

  1. ↑ W. Left: Orientation with map, compass, GPS. Delius Klasing Verlag, Bielefeld 2011, ISBN 978-3-7688-3314-1 , p. 97
  2. ↑ W. Left: Orientation with map, compass, GPS. Delius Klasing Verlag, Bielefeld 2011, ISBN 978-3-7688-3314-1 , p. 96
  3. ↑ W. Left: Orientation with map, compass, GPS. Delius Klasing Verlag, Bielefeld 2011, ISBN 978-3-7688-3314-1 , p. 117
  4. ↑ W. Left: Orientation with map, compass, GPS. Busse + Seewald GmbH, Herford 1996, ISBN 3-512-03155-2 , p. 100
  5. ↑ W. Left: Orientation with map, compass, GPS. Delius Klasing Verlag, Bielefeld 2011, ISBN 978-3-7688-3314-1 , p. 94
  6. ↑ W. Left: Orientation with map, compass, GPS. Delius Klasing Verlag, Bielefeld 2011, ISBN 978-3-7688-3314-1 , p. 95
  7. ↑ W. Left: Orientation with map, compass, GPS. Delius Klasing Verlag, Bielefeld 2011, ISBN 978-3-7688-3314-1 , p. 64
  8. ↑ F. Liebau: The basics of orientation and the handling of a compass with pedometers and map meters. Competence Center K&R, p. 32 ( PDF ( Memento of the original dated December 8, 2015 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this note. , Accessed on December 1, 2015) @1@ 2Template: Webachiv / IABot / www.kasper-richter.de
  9. ↑ https://de.wiktionary.org/wiki/Ververzeichnis:Deutsch/Soldatenssprache#E