In
The Observing Sky Atlas E. Karkoschka has a table on sky brightness that is supposed to help you figure out which faint fuzzies you can see on a given night. The table equates the brightness of a NYC sky to that of a mountaintop under a Full Moon. I wondered what it would be like in NYC under a full moon so extended the chart to include projections for large cities under other than New Moon conditions.
Illumination
| Mountains | or | New Moon |
| Field | or | Crescent (25%) Moon |
| Suburb | or | First/Last Quarter (50%) Moon |
| Small City | or | Gibbous (75%) Moon |
| Large City | or | Full Moon |
| Large City | and | New Moon |
| Large City | and | Crescent (25%) Moon |
| Large City | and | First/Last Quarter (50%) Moon |
| Large City | and | Gibbous (75%) Moon |
| Large City | and | Full Moon |
|
Sky Brightness
| 14/square’ |
| 13 |
| 12 |
| 11 |
| (10) |
| (10) |
| (9) |
| (8) |
| (7) |
| (6) |
|
after E. Karkoschka
numbers in ( ) are extrapolations |
