SunPosition Calculator FAQ
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I forgot my User login / Password, what do I do?
Why is the Calculate button not enabled?
Why do location menus not update?
Is there a full list of locations available to SunPosition users?
How does the SunPosition calculator work?
Calculations seem to be out by 1 hour?
Is there a data Printout example page?
Is SunPosition compatible with all browsers?
How do I make calculations?
SunPosition and Google Maps?
Is there a SunPosition Dashboard Widget?
A location I want is not listed on SunPosition?
What is the SunPosition Forum?
Is SunPosition available in other languages?
Why do some airport locations have airport codes and others not?
What does (A) and [LEAM] in the location mean ?
What tools should I use with sunPosition?
How accurate are sunrise/sunset computations?
Where does SunPosition get it's information from?
Do SunPosition calculations differ from other calculations?
When is Sunrise and Sunset?
What is Twilight?
What is Daylight Savings Time?
Is the magnetic field different at different places of the Earth?
Does it cost anything to use SunPosition?
How is payment made?
What is our processors Security Policy?

I forgot my User login / Password, what do I do?

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Just use these 'Forgot User login' or 'Forgot Password' link and fill in the details then we will send a copy of your User login or Password to the e-mail address we have on record for you, this information will be sent as soon as you fill in and send the relative form from the above links.

Why is the Calculate button not enabled?

A selection from all the available location menus must be made before the 'Calculate' button will be enabled. It is recommended to have Javascript enabled in your browser for the SunPosition application to function properly. Most browser have this enabled so if you don't know what this means then you probably don't need to worry about it.

Why do location menus not update?

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On selecting a location menu the other relative location menus will update automatically if your browser is Javascript enabled, most browsers are Javascript enabled so unless you have selected to disable that option in your browser you probably don't need to worry about this. Selecting an option from the 'Continent/Region' menu will update the 'Country/State' menu values to relate to that selection, as will selecting an item from the 'Country/State' menu will update the 'Town/City' menu values. Note: After selecting from a location menu you will normally need to wait a few seconds for the next menu to load it's values relative to the menu item you have just selected so wait for the browser to finish reloading before trying to select from the next location menu. If your browser does not load the other menu items after making a selection from a location menu then you can use the 'Update List' button force the browser to update the other location menus.

Is there a full list of locations available to SunPosition users?

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A full list of locations currently available to members and non members can be browsed using the Full locations list page.

NOTE: When using the 'Calculator' non members do not get to view all the available locations, by using the list above they can see all the locations currently available to members, approximately 48,109 and growing. [Related]

How does the SunPosition calculator work?

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SunPosition uses an advanced mathematical algorithm to run calculations which are incredibly accurate, meaning you can be sure to know exactly where to expect the sun wherever and whenever you need to. Data used for the calculations are the selected date along with the location longitude, latitude, GMT offset and magnetic declination. Magnetic declination for locations is calculated using a 'C' modual written specifically for this purpose. These magnetic declination values constantly change for all locations on earth, so we update these values as often as needed to keep SunPosition calculations accurate.

Calculations seem to be out by 1 hour?

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Make sure the time zone is correct for the location you are making your calculations for, is DST (Daylight savings time) being used? you will need to select this option for your calculations if this is the case. If you feel the error to be in the SunPosition database then please Contact us with information about the calculation and location where you feel there to be an error.

If a location does not use DST then users will not be given the option to advance the time by one hour. If your selected location uses DST, but the date you have selected is not within that locations DST start and end dates, then any 'Advance by 1 hour?' selection will be ignored.

Is there a data Printout example page?

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Yes, non members can see an example of the 'Data Printout' page that members get access to for all 48,109 locations, go to the SunPosition Calculator page and select the location: 'Europe > Spain > MADRID (M)', when you make the calculation you will find the 'Data Printout' button to be enabled, press it and the results for your selected date or date range will open in another window formatted for allowing you to print the results to an A4 page. Note: Make sure your browser printer set-up is set to print the page in vertical 'portrait' format so the results are printed on 1 page only.

Is SunPosition compatible with all browsers?

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SunPosition is compatible with most modern browsers, pages use Javascript and members browsers will need to be set to accept cookies.
We recommend the following browsers:

Windows
Microsoft Internet Explorer 6 + above'

Macintosh OSX
Camino 1.0 + above
Safari 2.0 + above

Macintosh OS9
Opera 6.03

Below is a list of browsers SunPosition is known to work with, users will probably discover others that are not listed, by all means let us know of these by making sure the calculation and printer friendly 'Data Printout' pages load properly.
Non members can check if the 'Data Printout' page is compatible by selecting the following 'Data Printout page example' location of: 'Europe > Spain > MADRID (M)'.

Windows
Microsoft Internet Explorer 5 + above
Firefox 2 + above
Netscape 7 + above

Macintosh OSX
Camino 1.0 + above
Safari 2 + above
Opera 7 + above
Microsoft Internet Explorer 5.2 + above
Netscape 7.2 + above
Firefox 1.0 + above

Macintosh OS9
Opera 6.03
iCab 2.9.8 - Functional but with CSS layout issues
Netscape 6 - Functional but with CSS layout issues

How do I make calculations?

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SunPosition is very simple to use, it is fairly much self explanatory for anyone who is accustomed to making these types of calculations. A step by step process on How to make a calculation is available for those who have never made a SunPositioning calculation before. This document also outlines most of the differences in options for making a calculation for non members and members.

SunPosition and Google Maps?

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SunPosition locations can now be opened in Google Maps. Users can see exactly where a location is by selecing the 'Show on Google Maps' link after making a calculation or when browsing the Locations List. Members also have the added advantage of checking their Favourites locatons on Google Maps by using the 'Show on Google Maps' link in that favourites location detail, and in doing so check the location of a custom location.

Is there a SunPosition Dashboard Widget?

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SunPosition has a free Dashboard widget available to members with Macintosh computers OSX Tiger '10.4' or above. [More info] Members will need to enter their username and password to use the widget, they will be able to access all their member locations and open the data printout page from within the SunPosition widget.
The SunPosition widget is no longer free unless you have signed up to a SunPosition account, anyone who wishes to have and use the SunPosition widget will need to sign-up to SunPosition although they do not need to use the SunPosition online service they do need to be a member to get access to the SunPosition data.

IMPORTANT: Access to SunPosition by the SunPosition widget is controlled under the same user license restrictions applied to the SunPosition members user license.
Members can connect and gain full access to SunPosition using the SunPosition widget from any Macintosh running OSX 10.4 and above.
Members need to be aware that if they enter their username and password in a widget on another computer than their own and do not remove this information after making their calculation, then access to their account may be restricted by their user license and SunPosition. A single user license permits only one user to be logged into SunPosition at any one time from an internet browser or from a widget or instances of widgets on the same computer.

Members are advised not to give their member access to anyone, or leave that information within a browser or widget that is not on their own computer. Remember your member access to SunPosition will be restricted if SunPosition is being accessed by your account from another computer if you are trying to log in at the same time as the account is being accessed from another entity.

A location I want is not listed on SunPosition?

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Non members only get access to about 15% of the total locations, members have access to all 48,109 locations. Click here to browse the full list of all member and non member locations.

If there is a location that you need to make a calculation for and it is not listed, then let us know the location along with the UTC time offset 'if you know it' and we will add it to the SunPosition locations list, Request to add a location. Another way of getting a new location added is to post a 'New location request' in the SunPosition Forum. Don't worry if you do not have the longitude or latitude for your requested location, we will add that data along with the magnetic declination and UTC if you do not know these. A requested location needs to be a town, city or a known land mark so we can reference it's longitude and latitude.

What is the SunPosition Forum?

The Forum is no longer online.

Is SunPosition available in other languages?

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The actual SunPosition website is in English only but members can select from 4 different languages for the calculation data printouts. The languages are: English (Default), Spanish, French and German. To change the language of the data printouts you need to edit the data printout language setting....

1# Login to your SunPosition account.
2# Select '<< Account admin'.
3# Select 'Edit - User settings'.
4# Select the language from the 'Data printout language' menu.
5# Save changes

Changing this setting will affect data printouts made directly from the SunPosition website and accessed from the SunPosition Widget, this will affect no other part of the site.

Why do some airport locations have airport codes and others not?

The airports that do not have a code and just use the word [Airport], are locations that we do not yet have airport codes for, over time we will gradually update these airport codes where possible. [Related]

What does (A) and [LEAM] in the location mean ?

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Some countries have an abreviation in brackets after the name, for example 'Aguadulce (A)'. This helps inform the user as to which province or region the location is in, in this case (A) is used for the province of Almeria. With locations in the United Kingdom (NI) would be used for a location in Northern Ireland etc., not all countries or locations will use this.
Airport locations use square brackets containing the airport code to inform the user that the location is an airport, for example: 'Almeria [LEAM]' would be used for Almeria airport, if the airport code is not known or has not yet been updated the square brackets will contain the word Airport, e.g. [Airport]. [Related]

What tools should I use with sunPosition?

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Generally you can use any reasonable quality Compass or Clinometer you wish, although we recommend Suunto products. Suunto manufacture high quality precision instruments that return outstanding reliability. Sunnto products are manufactured in Finland and they have distributors throughout the world. You can find a distributor near you by visiting the Suunto web site.

How accurate are sunrise/sunset computations?

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SunPosition calculations are probably as accurate as it is possible to get with any computer program, on saying this the times of sunrise and sunset phenomena cannot be precisely computed to 100% accuracy on any computer program, because in practice, the actual times depend on unpredictable atmospheric conditions that affect the amount of refraction at the horizon. Thus, even under ideal conditions (e.g., a clear sky at sea) the times computed for sunrise or sunset may be in error by a minute or more, normal atmospheric refraction at sea level has been accounted for in SunPosition calculations. Local topography (e.g., mountains on the horizon) and the height of the observer can affect the times of sunrise or sunset even more. Generally it is not practical to attempt to include such effects in routine sunrise/sunset computations, in most cases the altitude of the location should not have an adverse affect on results used for general use. The accuracy of sunrise and sunset computations decreases at high latitudes.

Where does SunPosition get it's information from?

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The initial base for the SunPosition locations database was mostly populated using just over 47,000 location names, along with their latitude and longitude coordinates extracted from over 6 million locations supplied by The National Geospatial-Intelligence Agency (NGA) and The Geographic Names Information System (GNIS). The magnetic declination was calculated then the UTC Time zone offset was added for each location, all these values are then used by SunPosition to make the sun''s path and position calculations.

Do SunPosition calculations differ from other calculations?

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Most other web based programs for calculating the suns path or position do not take into consideration magnetic declination, SunPosition gives the option to compensate calculations for magnetic declination, by default this is selected. If you want true north calculations then just select that option. If you are using a compass then you should be using calculations that have been compensated for magnetic declination. More on Magnetic Declination.
Another good reason to use SunPosition.

When is Sunrise and Sunset?

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Most countries consider Sunrise and Sunset to be when the sun is at an altitude of -0.833 degrees 'atmospheric refraction accounted for', this is when the upper edge 'rim' of the sun touches the horizon. One of the exceptions is the Swedish national alamancs, which use -0.583 degrees 'atmospheric refraction accounted for', this is when the center of the Sun's disk touches the horizon.

For computational purposes, Sunrise or sunset is defined to occur when the geometric zenith distance of the centre of the Sun is at 90.8333 degrees, or '0.833 degrees' below the horizon, in other words... when the upper edge of the sun touches the horizon.

What is Twilight?

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There are three definitions of twilight: Civil twilight, Nautical twilight and Astronomical twilight. SunPosition uses Civil twilight for any Dawn and Dusk results.

Civil twilight, 'Civil dawn' is defined to begin in the morning, and 'Civil dusk' to end in the evening when the center of the Sun is geometrically 6 degrees below the horizon. This is the limit at which twilight illumination is sufficient, under good weather conditions for terrestrial objects to be clearly distinguished. At the start of morning civil twilight, or end of evening civil twilight, the horizon is clearly defined and the brightest stars are visible under good atmospheric conditions in the absence of moonlight or other illumination. In the morning 'Before' the beginning of civil twilight 'Civil dawn' , and in the evening 'After' the end of civil twilight 'Civil dusk' , artificial illumination is normally required to carry on ordinary outdoor activities. Complete darkness however, ends sometime prior to the beginning of morning civil twilight and begins sometime after the end of evening civil twilight.

What is Daylight Savings Time?

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Many countries use Daylight Savings Time 'DST' during their summer time. DST is when the clock is advanced 'in most cases' by one hour in summer. SunPosition can advance the hour for your location if DST is used at that location, simply by selecting the 'Advance time by 1 hour' checkbox, this will appear after selecting the actual location you want to make your calculator for, until this time the option will not be visible.

If a location does not use DST then users will not be given the option to advance the time by one hour. If your selected location uses DST, but the date you have selected is not within that locations DST start and end dates, then any 'Advance by 1 hour?' selection will be ignored.

Is the magnetic field different at different places of the Earth?

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Yes, the magnetic field is different in different places. In fact, the magnetic field changes with both location and time. It is so irregular that it must be measured in many places to get a satisfactory picture of its distribution. This is done from the approximately 200 operating magnetic observatories worldwide and at several other temporary sites. However, there are some regular features of the magnetic field. At the magnetic poles, a dip needle stands vertical (dip=90 degrees), the horizontal intensity is zero, and a compass does not show any true direction. At the north magnetic pole, the north end of the dip needle is down at the south magnetic pole, the north end is up. At the magnetic equator the dip or inclination is zero. Unlike the Earth's geographic equator, the magnetic equator is not fixed but slowly changes.
East declination is positive, west declination is negative.

The following is an image of how the magnetic declination has altered between 1590 and 1990. (Image supplied by usgs.gov)

EarthMagneticFieldDeclinationfrom1590to1990a

Does it cost anything to use SunPosition?

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SunPosition is free for basic use, so you can make calculations from just over 8,000 locations that are available to non members in the location menus.
Signing up will give you many more options, such as:

# Total access to the full list of 48,109 locations worldwide, this will also include locations other members have made accessable to members.

# Make calculations for specific latitude and longitude values that you can enter in either degrees, minutes and seconds or decimal degrees.

# Access to a page specially formatted for printing your date range, or selected date calculations along with a graph for the selected days calculations, this is formatted to print to an A4 page, just make sure you set your printer to print to A4 vertical 'portrait'. Non members can try an example of this 'Data Printout' page by selecting the location: 'Europe > Spain > MADRID (M)'.

# Saving existing or new locations to your favorites menu for instant access.

# Access to locations other members have made and allowed member access to, and more...

SunPosition is an on-going development process, users will find refinements and additional options being added over time, any suggestions from users that will add to or improve SunPosition will be gratefully received.

How is payment made?

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SunPosition uses eSellerate to handle our payment process, all major credit cards are accepted and credit card payments are made over a secure connection. Customers in Spain with a Spanish bank account have the added option of paying by direct debit if preferred. One of the advantages of making payment by Direct debit is that payments are recurring, so you don't need to renew your SunPosition license every 1 to 3 years, as this will be done for you automatically. Direct debit payments can be cancelled at any time by contacting us by e-mail up to 30 days before your renewal payment is due, or simply closing your SunPosition account from your member administration area up to 30 days before your next payment is due, will stop any further direct debit payments.

What is our processors Security Policy?

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When you purchase products using a credit card through sunposition.net, our payment processors protect the transaction with the strongest exportable standards of encryption. They require Secure Sockets Layer (SSL) connections on pages where personal data and credit card information is entered and displayed. When on these pages, you should see your browser's indicator that a secure connection has been made. For example, on Microsoft Internet Explorer, this is represented by a padlock on the status bar at the bottom of the browser windows. Clicking on this padlock will bring up more information on the encryption technology used by our processors web servers.

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Non members can search 7,954 locations from 242 countries worldwide.

Members can currently search 48,109 locations from 242 countries worldwide.

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