The command Polar clock as PDF in the Telescope menu lets you produce a PDF document in which the positions of reference stars around the pole are displayed for each hour throughout the night of the current date. This file can then be printed and used to polar align a telescope mount. This provides a rather simple and quick way to polar align a mount equipped with a polarscope, even if only Polaris is visible in the polarscope. Experience shows that it is easy to achieve a reasonable polar alignment with the help of this kind of diagram. A more accurate polar alignment needs a more precise procedure such as the King method.
The figure below shows an extract from one of the two pages produced in the PDF file:
One diagram is produced for each hour from sunset on the current date. The stars used are those defined in the Wap.prs file in the folder "C:\Users\<user name>\My Documents\C2aw" (under Windows 7) which is the folder that contains the user files. By default, C2A will look for the Wap.prs file first in this folder, and if it is not found, it will look for it in the folder "C:\Users\<user name>\AppData\Local\C2aw" (under Windows 7) and then in the installation folder (by default "C:\Program Files\C2A", or "C:\Program Files (x86)\C2A"). An example of such a file is provided in the standard version of C2A in the installation directory.
C2A’s installation directory. By default the stars Polaris, SAO 2937 (Yildun or delta Ursae Minoris) and SAO 1168 are present in this file. Indeed, these are the stars commonly used in polarscopes. However, there is nothing to prevent you from choosing your own stars. Stars are displayed in grey, except specifically Polaris (displayed in yellow) and SAO 1168 (displayed in red). Star sizes are consistent wit the magnitude scale.
The positions of the reference stars on 12 consecutive hours for the night of the current date. Symmetries can be applied to the field so that it corresponds to the view through the polarscope. These symmetries can be defined in the Misc tab of the Telecope interface options box.