Photons & Magnitudes

It is interesting to see, how many photons reach a area from a star with given magnitude (and color).

mag   Photons / m² / s
0        22.400.000.000
2        3.550.160.751
4        562.662.561
6         89.176.006
8         14.133.445
10         2.240.000
12         355.016
14         56.266
16         8.918
18         1.413
20         224
22         36
24         6
26         1

How many photons does an eye need to see a visual limit (A0) star?

This is for the v-band. The eye has about 7mm diameter thus about 0,000038 m² area.

This leads to some 2700 Photons per sec.

A more detailed article can be found here.http://articles.adsabs.harvard.edu//full/1993JRASC..87..123R/0000123.000.html