On-line Help System
An interactive printer-friendly PDF file version of this help information is included with NightCal when you download it. You will need a copy of Adobe Acrobat Reader® to read or print the printer-friendly version. If you do not have a copy of Adobe Acrobat Reader installed on your computer, you can download a free copy from www.adobe.com. If you want a separate PDF version of this documentation please e-mail us at firstname.lastname@example.org.
NightCal is a simple, practical, tool for basic observation session planning. It is designed to produce a monthly calendar telling you when it gets dark, when the Moon rises and sets and what the Moon should look like when it does make an appearance. NightCal also provides information about the visibility of Mercury and Venus and planetary conjunctions. NightCal is not designed to be an all-singing, all-dancing repository of all human knowledge about the Moon and planets or a tool for detailed planning of observing sessions; there are much bigger and better books, computer programs and websites available to do that.
The philosophy behind NightCal is to only provide information that will be of practical use to the amateur observer and not to just provide information for the sake of it. The calendar can be printed so that you can stick it on your notice board at home or in your observatory or it can be saved as a graphics file for inclusion in local astronomical society newsletters or publishing on the web.
|System Requirements and Installation|
NightCal should run on pretty much any machine with Windows '98 or above and a Pentium or equivalent processor. However, on low specification machines calendar build times may take a while (up to 90 seconds on very basic machines).
NightCal will take up 3.5 Mb of space on your hard disk.
There is no Linux or Mac version of this software.
To install NightCal run the NightCal set up program ‘NCalsetupxxx.exe’ (where 'xxx' is the version number). The set up program sets a default installation folder of C:\Program Files\NightCal. You have the opportunity to change this to an alternative installation folder. If you have already a copy of the previous version of NightCal (version 0.6.2) installed on your computer in the default folder, NightCal should retain your existing location/time settings.
If you already have a copy of NightCal 0.7.2 installed on your computer, the installation program may give you the choice to uninstall this version first:
- If you choose 'NO', your existing location/time settings should be retained.
- If you choose ‘YES’, YOU MAY LOSE ALL YOUR EXISTING OBSERVING LOCATIONS. We suggest that you write down the name, longitude, latitude and time zone for each of your observing locations before you remove the previously installation of version 0.7.2 of NightCal. See the Known Bugs section of this web site for details of a Vista installation problem experienced by some users and how to fix it.
The preferred method of uninstalling NightCal is via the 'Uninstall' shortcut in the NightCal folder in the Start menu. During the uninstall process you will be prompted as to whether you wish to keep the user settings stored in the NightCal initialisation file. If you choose to keep these settings, the NightCal folder will not be deleted and the user settings, including details of location longitude and latitude and time zones will be retained. If you choose not to keep this file, you will have to re-enter this data when you next install NightCal.
If the uninstall shortcut is not available, you can uninstall NightCal via the Control Panel, Add or remove Programs screen. If all else fails, you can uninstall NightCal by simply deleting the NightCal folder. If you use this method you will have to manually delete the Start menu entries and desktop shortcut. If you wish to keep your user settings, do not delete the NightCal initialisation file (NightCal.ini).
See the main homepage for the latest details of any bugs found.
|Location/Time Zone Screen|
This is the main program control screen and, after the splash screen, is the first screen you will see when you start up the program. Exiting this screen will close down the program. Use this screen to select your location and time zone and the month for which you wish to generate a calendar. To add a new location and/or time zone or to edit or delete an existing location, click on the 'Edit Locations/Times' button.
To generate a calendar simply select your location from the drop down list and select the month and year you wish to view (this defaults to the current month), then press the 'Make Calendar' button and wait for NightCal to do its stuff. Details of the location you have selected and the month and year of the calendar will be displayed in the Title bar of the calendar.
NightCal cannot display more than one calendar at a time. If you ask NightCal to display a second calendar window it automatically deletes the original calendar and displays the new one instead.
|Edit Locations/Times Screen|
Use this screen to set up a new location or to edit or delete an existing location.
To set up a new location, enter the name of your location and its longitude and latitude in either degrees, arc minutes (') and arc seconds (") or in decimal degrees. To select which format you wish to input this data, go to the General tab in the Options screen. Make sure you select the correct units of measurement as it is easy to confuse decimal degrees (written thus 52.12 degrees; equivalent to 52o 7' 12"degrees) with traditional system (written thus 52o 12' 00"degrees; equivalent to 52.20 decimal degrees).
Also be careful to select the correct North/South option for latitude and East/West option for longitude. An easy way to find the longitude and latitude of your observing site is to look up your location at www.multimap.com; the longitude and latitude of the site is displayed below the map in both traditional and decimal form.
Next select your time zone by entering how many hours ahead or behind Universal Time (UT), also known as Greenwich Mean Time (GMT), your location is. If you like to have your timings displayed in Universal Time, simply select zero. Version 0.7 allows the selection of time zones in half hour increments.
For information about dealing with Daylight Saving Time (DST), in the United Kingdom known as British Summer Time (BST), see Daylight Saving Time below. Finally press the 'Add' button.
To edit an existing location, select the desired location from the list at the bottom of the screen. Next make any changes you wish to the name, co-ordinates or time zone of the location, then press the 'Replace' button. A dialogue box will appear asking you to confirm this edit.
To delete a location, select the desired location from the list at the bottom of the screen, then press the 'Delete' button. A dialogue box will appear asking you to confirm this deletion.
To leave this screen and save your changes or additions, make sure you review any additions, deletions or edits you have carried out then press the 'Accept Changes' button. If you decide not to save your work in this screen, press ' Discard Changes' to exit.
|Daylight Saving Time|
Many countries operate a system of Daylight Saving Time (DST), known as British Summer Time (BST) in the UK. NightCal does not yet have a system for calculating DST. We would suggest that for a month in which a switch between DST and local time occurs, simply print off two calendars for that month, one based on DST, the other on local time. The easiest way to do this would be to set up two location profiles for your chosen site, one for local time, one for DST and name each accordingly (e.g. ‘Worcester’ = UT, ‘Worcester DST’ = UT + 1).
Most countries that observe daylight saving time are listed in the table below. They all save one hour (local time + 1 hour) in the summer and change their clocks some time between midnight and 3 am.
The contents of this table are reproduced with permission from http://webexhibits.org/daylightsaving where you can find a fuller discussion of daylight saving time.
Overview - This is the main output screen for the program. At the top of each calendar is a Title bar that displays information about the location and date to which the calendar relates. Below this is a calendar of astronomical ephemerides for the month selected. This calendar can be printed or saved for use in other applications or for publishing on the web. (Please see the Licence Agreement for terms and conditions for publishing material generated by this program).
Title bar - The title bar displays the selected month and year together with either the time zone and longitude and latitude of the observation point location as selected in the Edit Locations/Times screen, or the name of your observing site as entered in the Edit Locations/Times screen. To select which option you want displayed in the title bar, go to the General tab in the Options screen
Moon phase graphic - The Moon phase graphic displays a view of what the Moon will look like just before midnight each night. The image of the Moon displayed on any particular night should not be used as a guide to what specific lunar features will be visible on that night as the lunar image used is far too small.
The Moon phase graphic is automatically orientated for whichever hemisphere your selected observing location is situated in. If southern hemisphere users wish to have the Moon displayed in the northern hemisphere orientation, the automatic orientation control can be switched off in the Options screen.
For a description of what lunar features are visible on any particular night, We would recommend that you download Virtual Moon Atlas or visit the website Inconstant Moon. For a good beginners' night-by-night field guide consult the excellent little book Discover the Moon by Jean Lacroux and Christian Legrand (ISBN 0521535557).
Moon age – The figure displayed in the centre of the Moon phase graphic is the number of nights that have elapsed since the last New Moon. When the Moon is again at New Moon the word ‘New’ is displayed. The word ‘Full’ is displayed instead of the Moon age on the 14th night after the last New Moon. Version 0.7 brings NightCal in to line with the normal convention of the New Moon being defined as the day in which the New Moon actually occurs, rather than the previously used alternative convention of rounding this to the nearest day.
Point of libration – This is the point on the Moon's near side that is most tilted towards the Earth. This is displayed by placing a small red inward-facing arrow within the perimeter of the Moon phase graphic at the point of libration.
Angle of libration – The angle of libration is the angle (in degrees) that the limb of the Moon is tilted toward the Earth. This is calculated geocentrically and is displayed in the top left hand corner of the Moon phase graphic.
|Rise and Set Times|
Sun rise – The time at which the uppermost part of the Sun rises above the horizon at the chosen location. This calculation takes in to account refraction of sunlight through the atmosphere.
Sun set - The time at which the uppermost part of the Sun falls below the horizon at the chosen location. This calculation takes in to account refraction of sunlight through the atmosphere.
Twilight - The time at which the centre of the Sun's disc is a set number of degrees below the horizon at the chosen location. NightCal only displays the timings of evening twilight and does not display morning twilight timings. There are three user options available in the Options screen. Civil twilight (6 degrees), Nautical twilight (12 degrees) and Astronomical twilight (18 degrees - default).
When there is no twilight (i.e. in mid-summer in many locations) the symbol '--:--' is displayed in place of the time.
Moon rise –The time at which the uppermost part of the Moon rises above the horizon at the chosen location. When there is no Moon rise on a particular day, the space where the symbol and time would usually be displayed is left blank.
Moon set - The time at which the uppermost part the Moon falls below the horizon at the chosen location. When there is no Moon set on a particular day, the space where the symbol and time would usually be displayed is left blank.
When there is neither Sun rise nor Sun set because the Sun is always below the horizon (i.e. in mid winter in polar locations) the Sun rise symbol and time are omitted and the symbol '--:--' is displayed in place of the time next to the Sun set symbol, indicating that the Sun is below the horizon. Similarly, when there is neither Sun rise nor Sun set because the Sun is always above the horizon (i.e. in mid summer in polar locations) the Sun set symbol and time are omitted and the symbol '--:--' is displayed in place of the time next to the Sun rise symbol, indicating that the Sun is above the horizon. A similar protocol is adopted for Moon rise and Moon set in similar circumstances.
Inferior planets - NightCal displays the elevation of Mercury and Venus above the horizon at civil twilight. If a symbol is followed by ‘--‘ this indicates that the planet is less than one degree above the horizon, or is below the horizon, at civil twilight. A planet’s symbol with an upward pointing arrow indicates that the planet is visible in the morning sky (i.e. visible near Sun rise) whilst a downwards pointing arrow indicates that it is visible in the evening sky (i.e. visible near Sun set). If the symbols for Mercury or Venus are missing it is because this option has been turned off in the Options screen.
Mercury visible Mercury visible Venus visible Venus visible
in evening sky in morning sky in evening sky in morning sky
Example of inferior planets symbols.
Planetary conjunctions – For the purposes of this program, planetary conjunctions occur when any planet appears to be within 5 degrees of another planet as viewed from the Earth. NightCal calculates this information based on a geocentric calculation for all the planets except Pluto. A two letter abbreviation of the names of the planets concerned and their angular separation is displayed in green text in each calendar box. For example, if a conjunction between Mercury and Jupiter with an angle of 3.7 degrees is predicted, NightCal will display it thus Me-Ju 3o. If the apparent angle between two objects is calculated to be less than 1 degree, the conjunction is displayed in red text to warn the user of a close conjunction. For example, if a conjunction between Venus and Saturn with an angle of 0.8 degrees is predicted, NightCal will display it thus Ve-Sa .8o.
For instances of multiple conjunctions on the same night, NightCal only displays the information about the conjunction with the smallest angular distances between planets. However, to alert you to the fact that more than one conjunction is occurring, the green on white or red on white graphic is reversed to white lettering on green background or white lettering on a red background.
NightCal only calculates conjunctions involving at least one of the inferior planets (Mercury or Venus). The angles that define a conjunction and a close conjunction are configurable in the Options screen. The display of conjunctions can also be turned on or off in the Options screen.
Note: We've tried this green/red combination out on someone who is colour blind and it seems ok, but if you have problems, let us know and we will try changing the colour scheme.
|Printing, Saving and Web Publishing|
Printing - If you wish to print a calendar for daylight viewing and you have a colour printer, select 'Print Colour Image' from the Print drop down menu. When you select the Print function, NightCal sends a special high resolution (3194 x 2162 pixel) version of the calendar window to the default printer. NightCal automatically brings up the standard Windows print dialogue box. After setting the number of copies you require (default 1), and changing any printer setting you may wish to alter, NightCal automatically invokes a standard Page Set Up dialogue box. Whilst the minimum recommended printer resolution is 300 dpi, for maximum clarity we would suggest that you print out at resolutions greater than 600 dpi.
Printing defaults to a landscape format with a print margin of 20mm. Both of these parameters can be altered in the Page Set Up dialogue box. On starting a fresh printing session, NightCal will default to the last selected print orientation and print margins.
NightCal provides you with the option to print or save calendars in a format optimised for viewing printed output under red light conditions by producing a special greyscale image. To print a greyscale image directly, select 'Print Greyscale Image' from the Print drop down menu.
Example of special greyscale image created for viewing printed output under red light.
Saving.- NightCal allows you to save the calendar output to one of four different file formats and at one of two different resolutions. NightCal uses resolutions of 799 x 541 pixels for screen display and a much higher resolution of 3194 x 2162 pixels for printing. You have the option of saving files in either resolution. To save a greyscale image for later printing, save the calendar as a high resolution (3194 x 2162 pixels) file, making sure that you select the 'Greyscale' option in the Save Image Options dialogue box. You can then print this save file from another application.
The file formats available to the user are:
The biggest influence upon file size is the file format chosen, whilst the biggest influence upon quality is the image resolution. Low resolution images (799 x 541 pixels) are not very suitable for printing, but are ideal for web publishing, particularly in GIF or PNG formats
Section of low resolution (799 x 541 pixels) GIF output Section of high resolution (3194 x 2162 pixels) GIF output
Web Publishing - If you plan to post a calendar on a website, we suggest that you also include on the web page the key to calendar symbols we have produced in the form of a 64 Kb Gif file called 'key.gif ' (799 x 57 pixels). This file is included in the download and can be found in the folder containing the NightCal program file.
This series of tabbed screens gives you the ability to set your own values for displaying and printing information on the calendar screen. Select the relevant tab and make any alterations you wish on that and any other tabs. When you have made all the alterations to settings you wish to make, you have a choice of three buttons.
Calendar title bar - This option allows you to decide what information is displayed in the calendar Title bar. The options are either the latitude and longitude and the time zone you selected in the Location/Time Zone screen, or the name you gave to that combination of latitude and longitude and time zone in the Edit Locations/Times screen.
Latitude/longitude format - Allows you to switch between displaying and editing longitude and latitude in either degrees, arc minutes (') and arc seconds (") or in decimal degrees.
Start of the week - Allows you to make the calendar start the week on any day.
Moon display - NightCal defaults to automatically rotating the Moon graphic and point of libration through 180 degrees for all locations south of the equator. This option allows you to disable this function should you wish to do so.
Sun angle below horizon at evening twilight - This option allows you to choose whether the display of the time of evening twilight is for civil, nautical or astronomical twilight. See the Glossary for the definitions of these terms.
Planetary conjunctions - NightCal displays information on planetary conjunctions involving inferior planets, and displays close conjunctions using a red rather than green type. This options screen allows you to alter the default angles used to define a conjunction and a close conjunction.
Inferior planet elevations - You have the facility to turn the display of the elevation angle of each of the inferior planets (Mercury and Venus) on or off.
Meteor showers - This option is not yet implemented. In the next major release of NightCal, the program will have the option of displaying information of meteor shower maxima. This option will give you the facility to turn the display of this information on or off.
This menu gives you direct access to a number of resources to help you use NightCal.
NightCal Help - This is a shortcut to the file 'Help.pdf' in the NightCal folder. 'Help.pdf' is a printer-friendly version of this Help system. If you delete, move or rename the file 'Help.pdf', the shortcut will not work. Clicking on this link launches the file 'Help.pdf' in the default Acrobat® file reader installed on your computer. If you don't have an Acrobat file reader installed on your computer, you can download a free reader from www.adobe.com.
View QuickStart - This is a shortcut to the file 'QuickStart.txt' in the NightCal folder. 'QuickStart.txt' is a short text file summarising the key features of NightCal and how to use them. If you delete, move or rename the file 'QuickStart.txt', the shortcut will not work. Clicking on this link launches the file 'QuickStart.txt' in the default text file reader installed on your computer. This is usually Notepad.exe.
NightCal website - This is a link to the NightCal website. From here you can access the on-line help system. You must be logged on to the internet for this link to work.
About ... - This launches a small tabbed screen containing system information, a copy of the Licence Agreement, and links to the NightCal website and e-mail address.
Conjunction - When one solar system object passes within a small angular distance of another solar system object when viewed from a particular location.
Geocentric - With respect to the centre of the Earth.
Inferior planets - Planets whose orbits lies between the Earth and the Sun (i.e. Mercury and Venus).
Libration - Irregularities in the Moon's motion and other effects that lead to an apparent wobble of the Moon when viewed from the Earth. This results in about 59% of the Moon's surface being visible from Earth. The amount (in degrees) by which the limb of the Moon is rotated inwards towards the centre of the Moon's disc is referred to as the angle of libration. The point on the Moon's limb most rotated inwards towards the centre of the Moon is referred to as the point of libration.
Moon rise - The time at which the uppermost part of the Moon rises above the horizon.
Moon set - The time at which the uppermost part of the Moon falls below the horizon.
Occultation - When one astronomical object appears to pass behind another when viewed from a particular location.
Sun rise - The time at which the uppermost part of the Sun rises above the horizon.
Sun set - The time at which the uppermost part of the Sun falls below the horizon.
Topocentric - With respect to a particular point on the surface of the Earth.
Twilight (Civil) - The time at which the centre of the Sun's disc is 6 degrees below the horizon at the chosen location. At this time the brightest stars and planets will be visible under good atmospheric conditions and in the absence of moonlight or other illumination.
Twilight (Nautical) - The time at which the centre of the Sun's disc is 12 degrees below the horizon at the chosen location. At this time the sky is dark enough that all the brighter stars in the night sky will be visible.
Twilight (Astronomical) - The time at which the centre of the Sun's disc is 18 degrees below the horizon at the chosen location. This is the time at which the Sun does not contribute to sky illumination.
We want to hear from you about what you think of this software. So if you want to:
Please e-mail us at email@example.com
(NB: for security reasons, e-mails with no subject heading will not be opened).
Last updated - 7th July 2008
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Copyright© 2005-2007 Michael Morris