Question/Help: Identifying types of raw orbital and observation data

[Krys]

I know this is a slightly cryptic title! I have an old data set from some very old astronomy software from the 80s, that has some rather cryptic labeling I am trying to work out what the data actually *is* and also how to calculate the same data for newly discovered / tracked dwarf planets, so I can update the program with the new discoveries.

There are two sets of data I'm having issue with:

The first set is just identified as "Deg. Longitude start of 1980" and gives the following values:

Mercury: 231.2973

Venus: 355.73352

Mars: 126.30783

Jupiter: 146.966365

Saturn: 165.322242

Uranus: 228.070855

Neptune: 260.3579

Pluto: 207.439

I assumed at first these just referred to standard galactic longitude, but having crossed referenced the data against Stellarium for 1st January 1980, the numbers just don't fit.

The second set is the most cryptic, and is just labelled as "Brightness factor" with no further explanation. The obvious assumption would be an average apparent visual magnitude, but the figures again do not seem to fit. Is it possible they are altered to reflect apparent magnitude at a common distance (say 1AU?) to make calculation easier? The 1AU common distance is used in the program to generate angular sizes, so I suspect this is the case here but cannot be certain.

Mercury: 1.918E-06

Venus: 1.721E-05

Mars: 4.539E-06

Jupiter: 1.994E-04

Saturn: 1.74E-04

Uranus: 7.768E-05

Neptune: 7.597E-05

Pluto: 4.073E-06

If someone can recognize something from the data and give me more precise idea of what I'm looking at I'd really appreciate it.

Thanks