How to write down coordinates correctly. How to read GPS coordinates. Semi-free azimuth coordinate system
Latitude - the angle φ between the local direction of the zenith and the plane of the equator, measured from 0 ° to 90 ° on both sides of the equator. GEOGRAPHICAL COORDINATES - latitude and longitude, determine the position of a point on the earth's surface. On search engine maps, by default, coordinates are shown in degrees with a decimal fraction with "-" signs for negative longitude.
Eastern longitudes are considered to be positive, while western longitudes are considered negative. To fully determine the position of a point in three-dimensional space, a third coordinate is needed - the height. The main disadvantage in the practical application of G. S.K. in navigation there are large values \u200b\u200bof the angular velocity of this system at high latitudes, increasing up to infinity at the pole.
These coordinates are visible, for example, when laying routes from arbitrary points. Other formats are recognized during the search. The most common way to find a point on the surface of the Earth (globe) is generally known - using geographic coordinates called latitude and longitude. Parallels and meridians form a gridded coordinate system on the Earth's surface, with which any place on Earth can be pinpointed.
We can imagine the Earth as a sphere revolving around its own axis. The ends of the axis are the North and South Poles. The equator is a line of latitude with a value of 0 °. This means that the Equator is the starting point for measuring other lines of latitude.
All lines of latitude are parallel to the equator and are sometimes also called parallels. The equator divides the Earth into northern and southern hemispheres. North latitudes are positive and south latitudes are negative. Ultimately, it was decided that the line of zero longitude passes through the Greenwich Laboratory, located in England on the east outskirts of London. This line is also called the zero or Greenwich meridian.
What is longitude?
Each circle line can be subdivided into degrees with minutes and seconds. The degree of geographic longitude is 1/360 of the equator. The interval between 39 and 40 parallels is 1 ° latitude. The interval between 175 and 176 meridians is 1 ° longitude. Thus, a complete record of the geographical coordinates of the Ngauruhoe volcano: 39 ° 07 ′ S, 175 ° 37 ′ E. 39 degrees, seven minutes south latitude.
What is latitude?
A second of latitude is approximately 0.03 kilometers, or approximately 30 meters. At the equator it is approximately 111 kilometers, the same distance as latitude. The size of longitude gradually decreases and tends to zero, as the meridians converge at the poles of the Earth. So, at a latitude of 45 °, the degree of longitude is approximately 79 kilometers. As the degree of longitude changes in size, the minutes and seconds of longitude also change, decreasing in size towards the poles.
Almost all globes have lines of parallels and meridians. Also, many globes have a so-called meridian arc, which serves not only to keep the sphere of the globe on a stand, but also helps to determine geographic coordinates. There is a degree scale on the meridian arc (see photo). This scale is used to determine latitude. If there is no degree scale on the meridian arc, then such a scale is on the prime meridian (Greenwich) and on the date change line (meridian 180 °). But the longitude is determined by the equator.
If this point is above the equator, then it will be north latitude, if below the equator - south latitude. Then determine the longitude. To do this, you need to look at the numerical value of the intersection point of the equator and the meridian arc. This value should be viewed on the equatorial scale. It combines the beauty of levitation with modern technology.
The electromagnetic globe is a wonderful gift and souvenir for you and your friends. The geographical latitude of points lying in the northern hemisphere (northern latitude) is considered to be positive, the latitude of points in the southern hemisphere is negative. It is customary to speak of latitudes close to the poles as high, and those close to the equator as low. The choice of the prime meridian is arbitrary and depends only on the agreement.
Within the geographic envelope, ‘altitude’ is usually used, measured from the level of the “smoothed” surface - the geoid. Such a three-coordinate system turns out to be orthogonal, which simplifies a number of calculations. The orientation of the axes in the geographic coordinate system (GCS) is selected by the algorithm. The orientation of the XYZ trihedral, due to the rotation of the earth and the movement of the vehicle, is constantly shifting at angular speeds.
There are no uniform rules for recording coordinates. All GPS navigators and major cartographic projects on the Internet work in this coordinate system. The generally available accuracy when working with geographic coordinates is 5 - 10 meters on the ground. Coordinates are angular values \u200b\u200band are expressed in degrees. Geographic coordinates will appear in the search bar of the map (as well as in the panel on the right).
A panel with the address and geographic coordinates will appear under the search bar. The current location is usually captured as a waypoint from which coordinates can be read later.
At the same time, the numerical values \u200b\u200bof the coordinates remain available (they can be seen in the search bar of the map opened by the link). Please note - point markers displayed on the map are anchored to roads, and their position corresponds to the entered coordinates only approximately. The recording forms can be simply converted into one another (1 degree \u003d 60 minutes, 1 minute \u003d 60 seconds).
On Google maps and Yandex maps, first latitude, then longitude (until October 2012, the reverse order was adopted on Yandex maps: first longitude, then latitude). Longitude is the angle λ between the plane of the meridian passing through a given point and the plane of the initial zero meridian, from which the longitude is measured.
Gone are the days when GPS was the exclusive domain of navigators. Now the GPS receiver can be used in car alarms, video surveillance systems, cameras and phones. It has also become fashionable to indicate exact coordinates on business cards and websites instead of an address.
Many have come across the fact that coordinates look different on different devices, and attempts to get to the desired point by coordinates due to a mismatch in their recording system are accompanied by problems. Either you have to look for the right place additionally, focusing on signs, or in general the matter ends in failure. If we are looking for something noticeable, or if we know other landmarks, it is easily fixable. And the loss in GPS orienteering competitions due to incorrect reading of coordinates is easily experienced.
But situations can be more serious. For example, you have completely trusted your alarm system with GPS-tracking of the vehicle's location, for example, by installing the StarLine Pobedit security system or Pandora DXL 3700. The car was stolen, but you are calm knowing where to find it. When it comes to the practice of searching for it, problems suddenly begin: there is no car in the supposed place. Now imagine a much more serious situation: a person is in trouble, the coordinates of his whereabouts are known, but it is impossible to find him.
Why can this happen? The whole point is that a simple set of numbers, although very similar to each other, in mismatched coordinate systems can lead us to a completely different place.
About coordinate recording systems
The school geography course teaches that coordinates should be measured in Degrees, Minutes and Seconds. Therefore, the difference in spelling is often perceived as a whim of the interface designer. But is it? This is where the catch lies, which can lead to completely unexpected consequences.
Let's see how the three most common coordinate systems differ.
Familiar recording format: degrees, minutes, seconds
This format is used as a preset format, for example, in JJ Connect navigators. It looks like this: YYY ° MM "SS, S"
The coordinates look like this:
N 067 ° 27 "13.8"
E 034 ° 16 "59.9"
What does this mean in practice?
The maximum number of degrees that can be 180. Therefore, for latitude, where the maximum value is 90, a three-digit number is often used anyway. All three systems converge on this issue. The first zero is often omitted, but it is usually intuitively clear how many digits represent degrees. For our country, the numbers for the northern coordinate are always at least two - from 41 in the south to 90 degrees at the North Pole, and for the eastern - either two or three, from 19 for the Kaliningrad region to 170 degrees in the Barents Sea.
For all three coordinate systems, the last five digits represent fractions of a degree. In this coordinate system, minutes go on. There are 60 degrees of them. Minutes are followed by seconds (60 in one minute) and decimal (!) Fractions of a second. Confusion is added by the different format for separating decimal places in the American and European traditions - comma or period.
If you don't see the usual 'for minutes and "for seconds, for example, the coordinates look like this:
N 067 27 13.8
E 034 16 59.9
Or worse, like this:
N 672713.8
E 0341659.9
then this format can be recognized by a period or comma before the last digit.
The following notation format: degrees, minutes, decimal fractions of a minute
This format is used by default, for example, Garmin navigators. It looks like this: YYY ° MM.SSS "
For instance:
N 067 ° 27.230 "
E 034 ° 16.998 "
As seen, appearance coordinates are almost the same. There is a difference, but if it were not for the number 9, which suggests that these cannot be seconds (there cannot be more than 60, as we remember), then one would think that this is the same recording system. But no, here are minutes and decimal fractions of a minute to the third digit.
If the usual degrees and the minute sign at the end of the specified coordinates are absent, this recording format can be recognized by a dot or comma before the last three digits.
However, this approach also does not always give a 100% hit guarantee. For example, the MS-PGSM "Sputnik" security complex issues coordinates in a similar recording system, but the number of decimal places in minutes is not three, but four. In this case, the number of digits for degrees is different: for latitude there are 2 digits, and for longitude - three. It is easy to guess exactly this in this case due to the fact that here the period is obviously used to separate decimal parts of a number. Since there cannot be more than ninety degrees in latitude, the following color numbers mean minutes.
Type of recording the coordinates of the MS-PGSM "Sputnik" security complex
Finally, the third notation format: degrees, decimal fractions of a degree to the fifth decimal place
In this format, there are no minutes or seconds at all. All five digits represent only decimal fractions of a degree.
N 67.45383 °
E 34.28331 °
If there is no degree icon, it can be recognized by the fact that there are no periods or commas between the last five digits.
The decimal format for recording coordinates as a preset, for example, is used by Lexand navigators and StarLine security systems. This form of writing coordinates makes it easier to calculate the distance between different coordinates, since this requires the cosine of the latitude angle.
So what is this long introduction for?
If you look more closely at these numbers, different in appearance, it turns out that this is the same point in different coordinate systems!
Very often there are complaints at competitions, for example from Mercedes-Benz pilots, or when reading some navigator's sheets, that “here, we were given the coordinates of Garmin, and we searched for the exit for a long time, but did not find it”.
Indeed, having hammered the coordinates of the first recording system into the second and vice versa, it will be difficult to find what you are looking for, but theoretically possible. The difference between the resulting points at a latitude of 67 degrees will be about 200 - 300 meters.
For instance,
N 067 27 13.8 and N 067 27.138
E 034 16 59.9 and E 034 16.599
Between 27.138 "and 27" 13.8 "the difference will be as follows: in one second of latitude at this latitude 0.03087 km, that is, almost 30 meters. In our country, the error in latitude is 5.52 seconds, that is, 170 meters.
Longitude is no better: at this latitude, one second of longitude will be 0.01185 km, and the difference with the real coordinates of the place is almost 24 seconds. That is about 280 meters.
Instead of a point, we got a rough square of 300x200 meters. This is bad, especially if you consider that the navigator itself can give inaccurate positioning with poor satellite reception. But for many tasks, the difference is quite acceptable, so often people do not think about why they did not get exactly to their destination.
If you thoughtlessly drive numbers into the last recording format, then the error will be much more serious, if not to say that it will be fatal. One tenth of a degree of latitude is more than 11 km! And in longitude it is no better: in one tenth of a degree of longitude at an example latitude of more than 4 km. And the difference between the real coordinates of the point and the imaginary ones starts already in tenths of a degree!
What to do?
In most navigators, you can change the coordinate recording systems in the settings. If the coordinates offered to you do not coincide in appearance with what you see in the navigator, do not be too lazy to deal with the device and find out how the coordinate system changes. Unfortunately, this feature is often well hidden and not always easy to find.
However, in some cases, you cannot change the coordinate system. In this case, the coordinates of the points must be recalculated to bring them into line with each other.
Coordinate view by default in Lexand SG-555 and Garmin Rino 530HCx navigators
How to convert coordinates from one recording system to another?
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Initial data: degrees, minutes, seconds |
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YYY° MM "SS, S" in YYY° MM, MMM " |
New minutes are calculated as follows: SS.C "/ 60 + MM \u003d MM, MMM" |
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YYY° MM "SS, S" in YYY,YYYYY° |
Seconds and minutes are converted to decimal format: SS.C "/ 3600 + MM / 60 \u003d 0, YYYYY |
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Initial data: degrees, minutes, decimal fractions of a minute |
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YYY° MM, MMM "in YYY° MM "SS, S" |
To convert decimal fractions of a minute to seconds and decimal fractions of a second, you need (MM, MMM "- MM) * 60 \u003d SS, C |
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YYY° MM, MMM "in YYY, YYYYY° |
Minutes are converted to decimal fractions of a degree: MM, MMM "/ 60 \u003d 0, YYYYY |
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Initial data: degrees and decimal fractions of a degree |
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YYY, YYYYY° in YYY° MM "SS, S" |
integer part (0, YYYYY * 60) \u003d MM (0, MMM) * 60 \u003d CC, C |
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YYY, YYYYY° in YYY° MM, MMM " |
0, YYYYY * 60 \u003d MM, MMM |
Help: how many kilometers are in one degree?
Latitude
One degree of latitude is a constant unit. The meridian is 40007.86 km long. Therefore, in one degree of latitude, there is always a constant number of kilometers: 40007.86 km / 360 ° \u003d 111.1329 km.
Longitude
Since we are in a polar coordinate system - at the poles all longitudes converge - the number of kilometers in one degree of longitude depends on latitude. At the equator, the distance between longitudes is maximum.
The equator is slightly longer than the meridian and is 40,075.7 km. One degree of longitude at the equator has about the same number of kilometers as in latitude: 40075.7 km / 360 ° \u003d 111.3213 km. In order to calculate the number of kilometers in longitude at a particular latitude, you need to multiply this number by the cosine of latitude.
Those. in one degree of longitude at the 67th parallel from the example will be (40075.7 km / 360 °) x cos 67.45383 ° \u003d 111.3213 x 0.3834 \u003d 42.68 km
If you move closer to the equator, for example, to the 55th parallel to Moscow, then in one degree of longitude there will already be (40075.7 km / 360 °) x cos 55 ° \u003d 63.85 km
And in Sochi and Vladivostok at the 43rd parallel in one degree of longitude there will already be (40075.7 km / 360 °) x cos 43 ° \u003d 81.41 km.
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Latitude called the angle formed by the plumb line passing through a given point on the Earth's surface, and the equatorial plane (in Fig. 3 for point M, the angle MOS).
Wherever the observer is on the globe, his gravity will always be directed towards the center of the earth. This direction is called plumb or vertical.
Latitude is measured by the meridian arc from the equator to the parallel of a given point in the range from 0 to 90 ° and is denoted by the letter f. Thus, the geographic parallel eabq is the locus of points having the same latitude.
Depending on which hemisphere the point is in, the latitude is named north (N) or south (S).
Longitude called the dihedral angle between the planes of the initial meridian and the meridian of a given point (in Fig. 3 for point M, the angle AOS). Longitude is measured by the lesser of the arcs of the equator between the initial meridian and the meridian of a given point in the range from 0 to 180 ° and is denoted by the letter L. Thus, the geographic meridian PN MCPs is the locus of points with the same longitude.
Depending on which hemisphere the point is in, the longitude is called east (O st) or west (W).
Latitude difference and longitude difference
During the voyage, the vessel continuously changes its position on the surface of the Earth, therefore, its coordinates also change. The magnitude of the change in latitude Af, obtained when the vessel moves from the point of departure MI to the point of arrival C1, is called latitude difference (RSh). RS is measured by the meridian arc between the parallels of the departure and arrival points M1C1 (Fig. 4).
Figure: 4
The name of the RS depends on the location of the parallel of the point of arrival relative to the parallel of the point of departure. If the parallel of the point of arrival is located north of the parallel of the point of departure, then the RS is considered made to N, and if to the south, then to S.
The value of the change in longitude Al, resulting from the transition of the vessel from the point of departure M1 to the point of arrival C2, is called difference in longitudes (RD). Taxiways are measured by the smaller arc of the equator between the meridians of the point of departure and the point of arrival of the MCN (see Fig. 4). If during the passage of the vessel the east longitude increases or the west decreases, then the taxiway is considered to be made to O st, and if the east longitude decreases or the west increases, then to W. To determine the RS and taxiways use the formulas:
РШ \u003d φ1 - φ2; (1)
RD \u003d λ1 - λ2 (2)
Where φ1 is the latitude of the point of departure;
φ2 - latitude of the point of arrival;
λ1 - longitude of the point of departure;
λ2 - longitude of the point of arrival.
In this case, northern latitudes and eastern longitudes are considered positive and a plus sign is assigned to them, and southern latitudes and western longitudes are negative and a minus sign is assigned to them. When solving problems according to formulas (1) and (2), in the case of positive results of RS it will be made to N, and RD - to O st (see example 1), and in the case of negative results of RS it will be to S, and RD - to W (see example 2). If you get a taxiway result more than 180 ° with a negative sign, you need to add 360 ° (see example 3), and if the taxiway result is more than 180 ° with a positive sign, you need to subtract 360 ° (see example 4).
Example 1. Known: φ1 \u003d 62 ° 49 "N; λ1 \u003d 34 ° 49" O st; φ2 \u003d 72 ° 50 "N; λ2 \u003d 80 ° 56" O st.
Find RSH and RD.
Decision.
Example 2. Known: φ1 \u003d 72 ° 50 "N; λ1 \u003d: 80 ° 56" O st: φ2 \u003d 62 O st 49 "N;
Find RSH and RD.
Measured from 0 ° to 90 ° on either side of the equator. The geographical latitude of points lying in the northern hemisphere (northern latitude) is considered to be positive, the latitude of points in the southern hemisphere is negative. It is customary to speak of latitudes close to the poles as high, but about those close to the equator - how about low.
Due to the difference in the shape of the Earth from the sphere, the geographic latitude of the points is somewhat different from their geocentric latitude, that is, from the angle between the direction to a given point from the center of the Earth and the equatorial plane.
Longitude
Longitude - angle λ between the plane of the meridian passing through this point and the plane of the initial zero meridian, from which the longitude is measured. Longitudes from 0 ° to 180 ° east of the prime meridian are called eastern, to the west - western. Eastern longitudes are considered to be positive, while western longitudes are considered negative.
Height
To fully determine the position of a point in three-dimensional space, a third coordinate is needed - height... The distance to the center of the planet is not used in geography: it is convenient only when describing very deep regions of the planet, or, on the contrary, when calculating orbits in space.
Within the geographic envelope, "altitude" is usually used, measured from the level of the "smoothed" surface - the geoid. Such a three-coordinate system turns out to be orthogonal, which simplifies a number of calculations. Height above sea level is also convenient because it is associated with atmospheric pressure.
Distance from the earth's surface (up or down) is often used to describe a location, however not serves coordinate
Geographic coordinate system
The main drawback in the practical application of GSK in navigation is the large values \u200b\u200bof the angular velocity of this system at high latitudes, increasing up to infinity at the pole. Therefore, instead of HSC, a semi-free in azimuth SC is used.
Semi-free azimuth coordinate system
Semi-free in azimuth SC differs from HSC only by one equation, which has the form:
Accordingly, the system also has an initial position, that the GSK and their orientation also coincides with the only difference, that its axes and are deflected from the corresponding axes of the GSK by an angle for which the equation is valid
Conversion between GSK and semi-free in the azimuth of the SK is carried out by the formula
In reality, all calculations are carried out in this system, and then, for the output of the output information, the coordinates are converted into GSK.
Geographic coordinate recording formats
The WGS84 system is used to record geographic coordinates.
Coordinates (latitude from -90 ° to + 90 °, longitude from -180 ° to + 180 °) can be written:
- in ° degrees as a decimal fraction (modern)
- in ° degrees and "minutes with a decimal fraction
- in ° degrees, "minutes and" seconds with a decimal fraction (historical notation)
The decimal separator is always a point. Positive signs of coordinates are represented (in most cases, omitted) sign "+", or letters: "N" - north latitude and "E" - east longitude. Negative signs of coordinates are represented either by “-” or by letters: “S” - south latitude and “W” - west longitude. The letters can be in front or behind.
There are no uniform rules for recording coordinates.
By default, search engine maps show coordinates in degrees with a decimal fraction with "-" signs for negative longitude. On Google maps and Yandex maps, first latitude, then longitude (until October 2012, the reverse order was adopted on Yandex maps: first longitude, then latitude). These coordinates are visible, for example, when laying routes from arbitrary points. Other formats are recognized during the search.
In navigators, by default, degrees and minutes with a decimal fraction with a letter designation are often shown, for example, in Navitel, in iGO. Coordinates can be entered in accordance with other formats. Degrees and minutes format is also recommended for maritime radio traffic.
At the same time, the original way of recording with degrees, minutes and seconds is often used. Currently, coordinates can be written in one of many ways or duplicated in two main ones (with degrees and with degrees, minutes and seconds). As an example, the options for recording the coordinates of the sign "Zero kilometer of highways of the Russian Federation" - 55.755831 , 37.617673 55 ° 45'20.99 ″ s. sh. 37 ° 37′03.62 ″ in. etc. / 55.755831 , 37.617673 (G) (O) (I):
- 55.755831 °, 37.617673 ° - degrees
- N55.755831 °, E37.617673 ° - degrees (+ additional letters)
- 55 ° 45.35 "N, 37 ° 37.06" E - degrees and minutes (+ additional letters)
- 55 ° 45 "20.9916" N, 37 ° 37 "3.6228" E - degrees, minutes and seconds (+ additional letters)
Links
- The geographic coordinates of all cities on Earth
- Geographic coordinates of settlements on Earth (1) (eng.)
- Geographic coordinates of settlements on Earth (2) (eng.)
- Conversion of coordinates from degrees to degrees / minutes, to degrees / minutes / seconds and back
- Conversion of coordinates from degrees to degrees / minutes / seconds and vice versa
see also
Notes
Wikimedia Foundation. 2010.
See what "Geographic coordinates" are in other dictionaries:
See Coordinates. Mining encyclopedia. M .: Soviet encyclopedia. Edited by E. A. Kozlovsky. 1984 1991 ... Geological encyclopedia
- (latitude and longitude), determine the position of a point on the earth's surface. Geographic latitude j is the angle between the plumb line at a given point and the equatorial plane, measured from 0 to 90 degrees on both sides of the equator. Geographic longitude l angle ... ... Modern encyclopedia
Latitude and longitude, determine the position of a point on the earth's surface. Geographic latitude? the angle between the plumb line at a given point and the plane of the equator, measured from 0 to 90. on both sides of the equator. Geographic longitude? the angle between ... ... Big Encyclopedic Dictionary
Angular values \u200b\u200bthat determine the position of a point on the Earth's surface: latitude - the angle between the plumb line at a given point and the plane of the earth's equator, measured from 0 to 90 ° (north of the equator is north latitude and south is south latitude); longitude ... ... Marine dictionary
geographical coordinates - The generalized concept of astronomical and geodetic coordinates, when the deviations of plumb lines are not taken into account. [GOST 22268 76] Geodesy Topics Generalizing terms of the coordinate system EN geographic coordinatesgeographical coordinates DE ... ... Technical translator's guide
geographical coordinates - Values \u200b\u200bthat determine the position of a point on the earth's surface (latitude and geographic longitude). → Fig. 124 ... Geography Dictionary
Geographical coordinates - (latitude and longitude), determine the position of a point on the earth's surface. Geographic latitude j is the angle between the plumb line at a given point and the plane of the equator, measured from 0 to 90 ° on either side of the equator. Geographic longitude l angle ... ... Illustrated Encyclopedic Dictionary
Latitude and longitude, angular values \u200b\u200bthat determine the position of a point on the globe relative to the equator and the prime meridian. The latitude of a point is the angle between the equatorial plane and the plumb line at a given point; longitude - an angle composed by ... ... Geographical encyclopedia
Quantities that determine the position of a point on the earth's surface: latitude φ, measured by the angle between the plumb line at a given point and the plane of the earth's equator, and longitude λ, measured by the dihedral angle between the plane of the meridian of this point ... ... Great Soviet Encyclopedia
A map by GPS coordinates will help you find: an address, a place and find out them by latitude and longitude, as well as how to find a point, city, street, country on the map, find out the coordinates of the route location and how to get to the place. You will learn: How to see latitude and longitude on maps, How to find a place by latitude and longitude. Search by GPS coordinates. Just enter the latitude and longitude data, the service will display the point on the map. Also, by clicking on the map at the right place, the service will determine the coordinates of the clicked place on the map. Find by coordinates on the map of Moscow, St. Petersburg, Novosibirsk, Yekaterinburg, Nizhny Novgorod, Kazan, Chelyabinsk, Omsk, Samara, Rostov-on-Don, Ufa, Krasnoyarsk, Perm, Voronezh, Volgograd, Saratov, Krasnodar, Tolyatti, Tyumen, Izhevsk, Barnaul, Irkutsk, Ulyanovsk, Khabarovsk, Vladivostok, Yaroslavl, Makhachkala, Tomsk, Orenburg, Novokuznetsk, Kemerovo, Astrakhan, Ryazan, Naberezhnye Chelny, Penza, Lipetsk, Kirov, Tula, Cheboksarsk, Kaliningrad-Udol. , Magnitogorsk, Sochi, Belgorod, Nizhny Tagil, Vladimir, Arkhangelsk, Kaluga, Surgut, Chita, Grozny, Sterlitamak, Kostroma, Petrozavodsk, Nizhnevartovsk, Yoshkar-Ola, Novorossiysk
