Note: This post is 7 years old. Some information may no longer be correct or even relevant. Please, keep this in mind while reading.
The apparent diameter of the Moon varies with the Earth-Moon distance. Depending on the distance, the apparent angular diameter of the Moon is between 29.4 and 33.5 arcminutes. For best astrophotography results, one should pick a time when the moon is closest. Similar to my plot of the apparent size of Venus, I wrote a short program to plot the Moon’s apparent diameter (see featured image).