# Plot air mass (dialog)

The “Plot air mass” dialog is used to create a curve of air mass coefficients and altitudes as a function of time. These values to useful in data post-processing to compute the extinction coefficients.

## Activating the dialog

The dialog can be activated:

1. from the main menu: Plot ‣ Air mass.

## Making a plot of air mass

Plot air mass (dialog)

(1) It is possible to include all source files in the project or the files that are currently selected in the table of input files.

(2) Specify object’s designation and object coordinates into the edit fields. Enter object’s right ascension in hours. Use the hexagesimal format, separate the fields by a space character. Enter object’s declination in degrees. Use the hexagesimal format, separate the fields by a space character. Click the button (3) to retrieve object’s coordinates from a table of predefined objects or a catalog of variable stars.

(4) Specify observer’s geographic coordinates into the edit fields. Enter observing location designation (i.e. city name). Enter the longitude in degrees. Use the hexagesimal format, separate the fields by a space character. Enter ‘E’ character at the first position in a string to indicate that the location is on the eastern hemisphere or ‘W’ character for locations on a western hemisphere. Enter observer’s latitude in degrees. Use the hexagesimal format, separate the fields by a space character. Enter ‘N’ character at the first position in s string to indicate that the location is on the north hemisphere or ‘S’ character for locations on a southern hemisphere. Click the button (5) to retrieve observer’s coordinates from a table of predefined locations.

Click the button (6) to proceed.

See also

Air mass curve (dialog)