Last update 11 March 2009
Copyright © Peter Hayes 1999-2009.
for your personal use, the Source Notes
describe how to save a copy and how a place is defined.
- If you want to publish a copy, translation or pages using any of my code on
your internet web site you may do so, for non-commercial purposes, as long as you
include this copyright notice and let me know so I can advise you of any corrections,
my e-mail address is on my Home Page.
- For commercial uses please contact me for permission, which will be given for any
reasonable uses without charge other than a donation to a mutually agreed charity.
Astronomical Algorithms, first edition, by Jean Meeus, published by
Willmann-Bell and the web pages of
The code has been tested with the following browsers -
- Internet Explorer version 6 under Windows 2000 and version 7 under XP.
- Mozilla based browsers including
FireFox under Mac OS X
and Windows XP.
The following references were of use in the coding.
Several people have kindly pointed out errors, suggested improvements and
supplied code. The main contributors were Stephane Macrez and Nick Reid.
I used data from the US Naval Observatory
to check my results.
I also recommend the heavens-above site for
all sorts of astronomical tables and diagrams.
For those who want skymaps I have used and recommend
Stellarium free for Mac OS X, Linux and Windows.
Latest changes are also documented on the main page, this is the full history.
- 11 March 2009 corrected observer.js for daylight saving time changes not on the last Sunday of the month
- 13 August 2008 added and changed some sites in observer.js based on stellarium sites list
- 21 April 2008 moved one line in index.html to correct DST
- Version 7.1 change to display the local time for the selected observatory.
If you have a local copy you need to reload index.html, observer.js, datetime.js & util.js for
the version 7 changes.
- Removed the get date/time/zone button, use reset instead.
- Added code to reset1 to convert to observers local time
- Version 7.0 support for user defined locations
- Thanks to the webmaster at
Muskegon Astronomical Society for suggesting this change and testing it.
- Revised updateplace to reset to location on URL
- Changed table1 to support user changing place name
- Added updatename function
- Changes to reset1, rewrite1 and updatell to support changes
- In observer.js re-wrote the observatory function and initial value of observer
- In util.js added llstring to convert latitude and longitude
- Change observer.js for new USA daylight saving rules (01/2007)
- Version 6.7 Changes to clockhandler and table for get date/time/timezone
- Merge get date/time with get time zone buttons
- Attempt to derive daylight saving info from browser's host system.
Code based on method by
Dr. J R Stockton
- Version 6.6 Changes to index.html updateplace so the time is
kept consistent with using Name= on the URL.
- Version 6.5 corrections to index.html for time zones E of Greenwich.
- Always display value of zone as positive, E/W flag shows sign.
- Correct time differences for negative values.
- Version 6.4 mainly changes in index.html.
- In reset1 added support for location name as parameter.
- Removed onload from <head> as reset1 called later.
- Added some missing convertra calls (following rewrite1).
- Removed duplicate entry for Cheltenham in observer.js.
- Corrected some HTML in index.html to validate as 4.01 transitional.
- Version 6.3 corrections to time string routines in util.js
- Version 6.2 corrections to index.html
- In function reset1 correct month to observer.month twice.
- Version 6.1 corrections to index.html and util.js
- In function updatelocal check for a change to the timezone W/E option.
- In function reset1 set the daylight saving flag correctly for all cases.
- In function hmsstring correct a typo in the rounding code.
- Version 6.0 - major changes to display time zone and daylight
saving time differently.
The underlying code still uses a DST adjusted time zone.
Changes in index.html
- Change table1 replacing UTC-Civil Time with Time Zone and a DST button, and move
UTC-Civil Time to a dropdown menu.
- Changes to functions clockhandler, updatelocal, updateplace and reset1, for DST.
- Changes to reset1 so the default time is done better.
- Lots of changes to rewrite1 to support the changes.
- Version 5.5 - changes to index.html, util.js and observer.js
- 'local time' is now UTC corrected for longitude WITHOUT any daylight saving.
This is because of problems with 'unknown' locations.
- Made a daylight saving correction to reset1.
- Added Muskegon
- Version 5.4
- Corrected minor bug in full month tables if the date is after a daylight saving change.
- Updated the copyright notices.
- Version 5.3
- Added check for moon up or down all day when neither rise or set found.
- Fixed a silly bug in moon.js that missed a did not set during the day.
- Version 5.2
- Change in index.html so the default is Greenwich CIVIL time with any daylight saving correction
not UTC. This is purely a personal choice and people who make copies defaulting to other locations
may wish to remove it. It is clearly marked in the source.
- Version 5.1
- Corrected the location of Madrid and Malaga (West not East) and time zone for Anchorage in observer.js
- Version 5.0 (not really as major a change as version 3 to 4 was)
- Corrections fromOle Nielsen in moon.js and
planets.js for small terms to the obliquity of the ecliptic.
- Version 4.9 -
- Changes to index.html to default to the current date and time
at Greenwich and make the time differences more consistent.
- Version 4.8 -
- Add support for a monthly table in planets.js
- Add support for a monthly table in moon.js
- Changes to sun.js
- Add support for a monthly table.
- Correction for repeats if they cross the daylight saving change.
- Add the monthly buttons to index.html
- Version 4.7
- Added default.css, the same style sheet as for my home page.
- Correction fromOle Nielsen
in planet.js to use the right refraction correction and more places in
- Version 4.6 - Corrections from Dean Davis in moon.js
- Correct my transcription of table T45BL
- Correct my error in understanding the corrections for the eccentricity
of the Earth's orbit.
- Revised equations for Moons mean elongation and anomaly from Meeus second edition.
- Version 4.5 - In index.html
- Add noon button for the solar observers.
- Add table headers and change some button names.
- Change the introductory documentation for button changes.
- Version 4.4 - In index.html and notes.html
- change RTC button to Local Date/Time
- commented out the reset button (and for a short time the time zone
but restored that).
- updated the documentation
- Version 4.3 - Changes to most files
- Alter sun.js to create a sunrise routine
- Ensure for loop variables are declared with var, this to
prevent possible subtle bugs (yes I created one in doing the
- Version 4.2 - Changes to index.html and datetime.js
- Allow input of Julian date (based on code from Nick Reid).
- Correct a possible 1 second error in time input.
- Version 4.1
- Fixed a bug in planets.js due to changed order for repeated planets
and tidied up the source in the same file.
- Version 4.0
- Split the source into different files.
- Fix in index.html for time differences near midnight.
- Added other cities and towns to observer.js.
- Changed order for repeated planets.
- Version 3.7
- Fixed silly error with angular separation output.
- Added equation of time.
- Corrected Amsterdam location.
- Include daylight saving adjustment in local time.
- Made the table more compact by adding selection options for
UTC, local and siderial time and the time differences.
- Version 3.6
- Improved checking for crossing saving time changes.
- Added local time and changed original local to civil time.
- Change the initial setup of date, time and timezone.
- Added the zone button and changed RTC.
- Version 3.5
- Angular separations based on code from Stephane Macrez.
- Alt/Az to RA/Dec code from Nick Reid.
- Midnight button and more freedom inputting times not just
hh:mm:ss but hh:mm or hh.
- Check for daylight saving time changes after date input.
- Allow for leap years in daylight saving and repeated tables. The
astronomical calculations were always right.
- Add latitude and longitude after location name to top of pages.
- Express time zone as hours:minutes as most people know them that
- Version 3.4
- output bright stars altitude & azimuth in degrees & minutes.
- fixed bug for 'unknown' location date / time
- fixed a bug in repeat code & allow user to specify date / time
- Version 3.3
- Additions based on code from Stephane Macrez.
- bright stars
- RA/Dec to Alt/Az converter.
- French locations, I only used a few places though.
- Changed from monthly tables to repeat at user specified time,
interval and repetition count.
- Version 3.2 Added monthly Sun and Moon tables.
- Version 3.1 Daylight saving bug fixes and cosmetic changes to source.
- Version 3.0 First attempts to handle daylight saving time.
- Version 2.9
- Round to 24 hour clock for sunrise/set even if next day
- Fix HTML errors shown by Netscape 6
- Added the Default button and changed RTC to use Time Zone.
- Added the moon phase angle as well as % illuminated.
- Version 2.8 Move the notes sections to a new page
- Version 2.7 Changes removed for version 3.3
- Version 2.6 Fix a silly bug in the moon rise /set calculations
- Version 2.5 Try to speed up moon rise / set calculations
- Version 2.4 Added the illuminated fraction of the moon.
- Version 2.3 corrected a Sun rise/set bug at the equinox.
- Version 2.2
- Corrected moon azimuth/elevation bug
- Used the full Meeus table 45 (see notes for credits)
- Version 2.0 First release to the world of the internet
If you want to keep your own copy you need to save the files listed below.
If you click on the link with the right button you usually find a "save
as" or "save target" option on the menu. Please read
the copyright notice if you want to use the source
on a public web page. Many of the functions have a parameter obs which is
an observatory object as defined below. If you write your own code remember
that you will need to make a copy (my code shows how) because the object is
passed as a reference object.
Defines the front page and the table that drives everything else.
- default.css The style sheet I use.
Defines the observers places and functions that define them.
atlas array defines the list of places. The code uses
the first entry as the default location. Add any others you need.
place function defines how to describe other towns.
- latitude is degrees:minutes:seconds, ns is 0 for north and 1 for south
- longitude is degrees:minutes:seconds, we is 0 for west and 1 for east
- zone is the correction in minutes from local time to UT (Greenwich time)
without daylight saving, west of Greenwich is positive. This is shown
in the table as hours:minutes.
- The daylight saving start and end (dss and dse) are strings
month:week:day where month is 1:12, day is 0-6 (0=Sunday) and week is 1-5.
week 1 is the first week containing 'day' and week 5 means the last occurence
of day in the month (same as the Unix TZ rules). Set the string to a null
string if you don't know the rules. WARNING the code to try to work out
daylight saving is simple minded, it will probably get it wrong about the hour
of the change.
- latitude is in degrees, north is positive
- longitude is in degrees, west is positive
- values contained within observatory object
month values in range 1-12
tz timezone in minutes with any daylight saving (summer time) correction. See
Calendar and sidereal time functions.
The functions that define the suns position and heliocentric co-ordinates and creates the Sun page.
The functions that define the moons position and creates the moon page.
The planet functions.
The functions for the bright stars table.
The functions for the angular separation table.
Math functions in degrees.
Utility routines for printing dates times etc.