Airmass calculator
Latest version (Linux): |
1.0 |
Date: |
10/01/2002 |
Latest version (Windows): |
1.0 |
Date: |
20/01/2002 |
Once too often someone was wondering what might be the airmass for the
object he was observing. This information is often included in the
header of an image file at the telescope, but what about when you are
planning and selecting which object to observe and when. Well, now you
can download my simple (but exact) airmass calculator for that purpose.
The calculator uses the Earth radius and height of atmosphere to
extract an as exact as possible airmass for any given zenith distance.
If you don't like the standard Earth radius = 6378.14 km and
atmospheric thickness = 60.0 km you can modify the Airmass.ini file
(Linux version) or give new value for atmosphere in the programme (Linux
and Windows version).
In the programme you can give either zenith distance or altitude of your
object and the corresponding airmass is calculated accordingly.
The programme gives results in four/five decimal places, but I have
noticed that the way different computers and systems handle real numbers
and trigonometric functions produces slight errors on the last digit.
Download Windows98/NT/2000/XP executable (v. 1.0) from here:
File: Airmass.zip (160 kB) Contains: Airmass.exe (341 kB)
To get the programme, just unload and unzip the file into any folder.
To run the programme, place it on your desktop and doubleclick on it
or doubleclick on it in Windows Explorer. The programme will warn you
if you try to enter incorrect values. You can change any of the
values (zenith distance, altitude, airmass, Earth radius, or height
of atmosphere) and the programme will immediately and automatically
update the other values to match the one you typed in.
Download Linux executable (v. 1.0) from here:
File: Airmass.tgz (55 kB) Contains: Airmass (114 kB) and Airmass.ini (86 bytes)
To get the programme just download, untar, and unzip the file into any
folder (tar xvzf Airmass.tgz). If the command in the parentheses does
not work try to give the following two commands (gunzip Airmass.tgz
and tar xvf Airmass.tar). If even that does not work, try just command
(tar xvf Airmass.tgz).
To run the programme just type Airmass (and press enter). If the current
folder is not in the path you probably need to give command ./Airmass
instead. You can give either zenith distance or altitude of
your object and the corresponding airmass is calculated accordingly.
Airmass.ini is pure ASCII so you can use any editor to change values
therein.
If you find a bug in the programme, don't be afraid to send me email
about it so I can fix the programme. Thanks.