[Space] GURPS Handbook of the Planets

[ericthered]

Originally Posted by Brett

Is the availability of the GURPS Handbook of the Planets inhibiting the development of a proper tool for the job? Is the kind-of-okay the enemy of the good?

I've got a project I'm working on. At this point creating exactly what you want and editing existing stuff aren't too hot, but I actually have a navigation map and you can look at star systems and see whats on them.

[Daigoro]

Originally Posted by sjard

No, I'm saying is works just fine, no warnings. But Brett's doesn't without turning off a bunch of options.

Yeah, his works fine, but Brett's doesn't because he hasn't been whitelisted yet. Is what I meant.

[Whill]

This is an awesome tool, and it seems to work just fine with my Excel 2007. It's helped me catch a couple arithetical errors, and now it seems like I've gotten to the point where my math and this tool pretty much confirm each other.

But to be sure I am imputing info correctly for my planets, I thought I would try to create Earth with the system.

Putting in 1 star with 1 for solar mass and 4.6 for the age gives me a luminosity of 1.10 which pushes the orbital radius back to 1.05. (I guess I should say that I found an average surface temperature of 284 to result in a Blackbody of 278, which is what the book says Earth has on p.124.) But I'm sure there are rounding approximations built-in so I tried a system age of 4.5 and got an luminosity of 1.09 and an orbital radius of 1.04. I had to go all the way down to a system age of 3.5 to get all the Earth-standard 1s.

The rest of my imput... (I have conventional gas giant arrangement, radius of first gas giant 5.2, first gas giant first gas giant eccentricity of .05 if that makes any difference.) World Type Standard, subtype garden, atmospheric mass 1, worse atmosphere false, hydro coverage 71, diameter 1, gravity 1, first gas giant eccentricity .02, axial tilt 23, major moon 1 tiny, vulcanism and tectonics both moderate.

I do understand this tool is just an aid, but it seems to me that it needing a billion years difference to make the numbers work out correctly is significantly off.

Please help this novice. What am I doing wrong?

[Flyndaran]

Stars sometimes are a little hotter or colder than the average for their size. Even Gurps Space suggest a variability of something like 10%.

[Agemegos]

Originally Posted by Whill

I do understand this tool is just an aid, but it seems to me that it needing a billion years difference to make the numbers work out correctly is significantly off.

The problem is real, but it's not a coding error in the sheet. It's a faithful reflection of the same problem in the rules on Space p. 103–4. The table there gives a star of mass 1.0 M☉ the following: spectral class G2, L-Min 0.68, L-Max 1.6, and M-Span 10 Ga. Taking Age = 4.5 that gives:

L = MIN + [(A/S) × (MAX - MIN)]

= 0.68 + [(4.5/10) × (1.6 - 0.68)]

= 0.68 + 0.45 × 0.92

= 0.68 + 0.414

= 1.094

To get L = 1.0 you need

L = MIN + [(A/S) × (MAX - MIN)]

A = S × (L - MIN)/(MAX - MIN)

= 10.0 × (1.0 - 0.68)/(1.6 - 0.68)

= 3.48

I don't know how the problem came about. There could be transcription error in the table on p. 103. It could be that Sol is a twidge smaller and therefore cooler and dimmer than the mean for G2 stars. Sol could be idiosyncratically cool and dim for its mass (this does happen, as I discovered to my chagrin trying to estimate star's age from their spectral class and luminosity with star-catalogue data and an inversion of this formula). The authors of Space might have forgotten to use the bolometric correction somewhere in their calculations.

Anyhow, I appreciate — even share — your disappointment, but that isn't an error in the sheet that I am in a position to mend. Sorry.

[Whill]

I appreciate the replies. Thank you for confirming that I wasn't doing anything wrong there. After previous errors of mine I've later discovered, this is good news for me. Brett, there is no need to apologize. You have taken the system in the book and honored it faithfully in some ways and improved upon it in others. I am in your graditude.

May I please inquire as to formula you used for the number of inner and outer gas giant moonlets? I noticed some of the random results are above the maximums in the book, which of course means this tool yields results more like the gas giants in our solar system with many moonlets.

[Agemegos]

Originally Posted by Whill

May I please inquire as to formula you used for the number of inner and outer gas giant moonlets? I noticed some of the random results are above the maximums in the book, which of course means this tool yields results more like the gas giants in our solar system with many moonlets.

I'll look into that. I meant to faithfully implement the RAW, and if there is a discrepancy that is a mistake.

[Agemegos]

The formula I'm using for inner moonlets is "=IF($J<row>,MAX(0,T<row>+VLOOKUP($F<row>,tables!$ AZ$10:$BC$15,2,1)),0)". Column J contains an "is there a gas giant in this orbit" flag (and that bit seems to be working correctly, because I'm not getting moonlets in the wrong places). Column T is labelled as being a 2d6 roll and looks correct ("=VLOOKUP(S67,tables!$C$10:$D$20, 2, 1)"). Column F is the semi-major axis (radius) of the planet's orbit. tables!$AZ$10:$BC$15 looks like a table of the modifiers to the number-of-moons roll listed on Space p.111–113, and the second column is the one for inner moonlets.

The formula I'm using for outer moonlets is "=IF($J<row>,MAX(0,Z<row>+VLOOKUP($F<row>,tables!$ AZ$10:$BC$15,4,1)),0)". Column Z is labelled as a D6 roll and looks correct. The fourth column in tables!$AZ$10:$BC$15 looks correct for the modifiers for orbital radius to the outer moonlets roll listed on p.112.

Anyway, I don't see an obvious error in the code. Perhaps the table lookups aren't working the way I expected. Could you please give me the User Number, System number, and row of a result that looks wrong to you, and I'll try to track it down.

[Whill]

Uh, sorry to make you go through all that. I thought I saw 17 moonlets somewhere but I just looked back over the 4 systems so far and I can't find that. I see results of 0-12 inner moonlets and 0-6 outer moonlets, so I don't have any examples of exceeding the RAW after all.

But that does bring up another question. How does anything I do report back to you? I downloaded it and saved it 4 times so far on my computer. There all say User 1. The first 3 "systems" all say System 1. I haven't used the handbook to make a whole system yet. I just ran 3 of my planets from one of my systems through it for the planet info (so I'm not using the other random planets generated yet). I saved those 3 "System 1" files by planet name to differentiate. The 4th is where I tried to make Earth. Even though it says to use a positive integer, it allowed me to enter a System # of 0 for that one.

Am I interfacing with this incorrectly? If this document is still connected to a master through the internet, doesn't it tell you if pick a user # that is already in use and make you use one that isn't yet? If so, I guess it is possible but I find it unlikely no one else has already used "User 1". I'm sorry for my confusion and very much appreciate your help.

[Sunrunners_Fire]

Originally Posted by Whill

Am I interfacing with this incorrectly?

It doesn't connect back to a master. Its' entirely local.