It might be easier to estimate the total apparent magnitude by taking a piecemeal approach. For example, what is the total apparent magnitude of the Large Sagittarius Star Cloud? The Scutum Star Cloud? If you can get numbers for those discrete "objects" (which would be interesting in any case), then perhaps you can extrapolate to the whole band.
Have a look at Is it possible to capture geostationary satellites with DSLR?
See the excellent advice in this answer to Are any geosynchronous satellites visible with the naked eye?
No, but they are easily seen with a small telescope on a sturdy mount. March and September are the best times. Use an app to help you. My favorite way is to keep M11, the Wild ...
Geostationary satellites are often seen with telescopes and occasionally result in a
"Something Moved! Did I see a UFO?" sort of message.
If you have a tracking telescope aimed at a star in the same field if view of a geostationary satellite the satellite will appear to move against the background. It you turn off telescope tracking the satellite ...
You can work in magnitudes, but the magnitude scale is logarithmic. Instead you can use luminosity. The moon has a luminosity that is 400,000 times less than the sun, so the maximum theoretical "lunar irradiance" is about 0.0034 watts per square metre.
In practice, the luminosity at the surface is less than this, with Wikipedia quoting "how ...
We have apparent magnitude of stars, planets, DSOs.
That's true, and these are calculated from the total integrated brightness across the apparent size of the object for an observer on Earth.
What about the apparent magnitude of Milky Way?
Can it be estimated?
There are two options if one wants an apparent value:
Try to get the total integrated ...
The apparent magnitude of an object is dependent both on the luminosity of the object and on its distance from the observer. For example, the Sun's apparent magnitude is -26.7 (from here). But if you moved it farther away, the apparent magnitude would decrease (meaning the value would increase - magnitude here is on an inverted scale).
However, we can think ...