I'm hoping what I'm seeing is just confirmation bias and not how the game actually works, so I'm asking and hoping more analytical minds can assuage my fears. It seems like, with eleven Observatories, quite fewer than 11% of my rare astronomical events are automatically being observed. It was my assumption that each Observatory would add 1% to my chance to auto-observe, and so at 100 Observatories I would automatically generate a starchart (and some science) from every event (and have lots of them!). Isn't this right?

Does building more Observatories increase your chance to auto-observe, or is the base chance the limit?

2 Answers 2


Each observatory increases the chance to auto-observe, but the chance will never be 100% because it diminishes after 75%.

The relevant part of the code is the following (inside calender.js):

var autoChance = this.game.bld.getEffect("starAutoSuccessChance");  //in %
            var rand = this.game.rand(100);

                (this.game.ironWill && (self.game.rand(100) <= 25)) ||
                (rand <= autoChance)
                dojo.hitch(this, this.observeHandler)({}, true);

Every observatory increases your starAutoSuccesChance with 1, so 11 in your case. However, this.game.bld.getEffect does the hyperbolic effect which makes sure the chance does not become 100%. In another answer(which deserves more upvotes imo) this is perfectly explained, so I will not do it again.

Here you also see is that the chance is compared with a random number under 100 (rand <= autoChance) so the autoChance (or starAutoSuccessChance untill 75 observatories) is indeed the percentage of auto-observes.

  • Thank you. I'm aware of the hyperbolic effect, but didn't realize it applied to the auto-observe chance. As far as getting more upvotes, I agree, and wish to thank you for your quick and accurate with a little constructive criticism... Start your answers with a straightforward answer to the question, a sentence or two that "is the answer". Then explain in detail, if you wish. Save code excerpts for last. This focuses your reader on your answer. If they have to read past actual code before they get to something like an answer, they're less likely to upvote. Thanks, and I hope I helped! Sep 25, 2014 at 11:47
  • Thanks. I moved it around, so the answer is on top and then the code explanation comes. I'll try to keep this in mind for following answers.
    – Mathias711
    Sep 25, 2014 at 11:52
  • 1
    I wish I could better explain, as I feel rude telling you how to write your answers, but I did notice that your answers - while being wonderfully thorough and accurate, thanks to your willingness to dig into the code and figure out exactly what's going on - might be a little too technical for most users, and thus don't get all the upvotes they should. If nothing else, sorting the answer itself to the top so the reader can look at one sentence and already know your answer should help. I appreciate your excellent answers at least, and want to see you get the rep you deserve ^_^ Sep 25, 2014 at 12:00
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    The diminishing returns matter very little in this case, since you'll be getting SETI (and thus a fixed 100% auto-success rate) long before you get 75 observatories.
    – Brilliand
    Oct 3, 2014 at 21:06
  • @Brilliand I wasn't aware of that because I didn't get that far before my reset. However it perfectly answers the question so I don't understand the downvote (if it was from you). But thanks anyway for pointing it out. When I had quite some observatories it was quite 'annoying', the observe button every time.
    – Mathias711
    Oct 3, 2014 at 21:43

Yes, each observatory adds 1% to the auto-observe chance for astronomical events. This will allow you to accumulate starcharts while letting the game run overnight, but don't plan on getting this chance very high with observatories; there's a lategame upgrade (SETI) that fixes your auto-observe chance at 100%, regardless of observatories.

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