Adding the Forum's Community Calendar to Google is easy if you follow these steps:

First, you will need to save the URL For the Calendar using the following image as an example:

Right-click on the Subscribe link and then click on 'Copy Hyperlink' or 'Copy link address' depending on the browser you're employing. Once the link to the calendar is now on your computer's clipboard, we can move to step two.

Go to your Google Calendar page and browse down toward the 'Other Calendars' portion of the page on the left-hand column. Click on the down-arrow located just to the right of 'Other Calendars' and then click on 'Add by URL':

Paste the copied URL from Ad Astra into the dialog box:

Click on 'Add Calendar.'

You should now see "Community Calendar" located under 'Other Calendars' on the left-hand side:

From here, you can now manipulate the calendar by going into the options to do things such as rename the calendar, and add reminder rules. Google will now automatically update the calendar whenever Ad Astra makes changes to it.