Usage of particles in 明日、日本語のクラブがあるけど、行く？

Question

I have this sentence:

明日、日本語のクラブがあるけど、行く？

which has the given translation of

There’s Japanese club tomorrow, want to go? (lit: Tomorrow, Japanese club exists but go?)

I have two questions on this sentence. Firstly, since the sentence is referring to something occurring tomorrow, why wouldn't I have the は after 明日 so it becomes this?

明日は、日本語のクラブがあるけど、行く？

Second, what's the purpose of the けど particle? In English at least, I don't feel a need to introduce any contrasting feeling to the sentence since it's just a straight question. In short, why not this instead?

明日、日本語のクラブがある。行く？

Answer 1

First, There really isn't an equivalent for the けど in English. That is just the way they speak. Japanese is a very indirect language, and they tend to append a "but" word to just about everything, as I am sure you know. Without the けど it sounds blunt, and more like a statement of fact than what you would use in an invitation. If you were just trying to tell somebody "Hey, we have Japanese club tomorrow!" you could not use the けど.

The 明日は ｖｓ　明日、I believe is just a question of colloquial vs formal. I have never really heard anybody talking to those of their same 身分 say　明日は.

がんばって！

Answer 2

From what I've gathered through the linked posts in the comments, は is omitted since the emphasis of the sentence is not quite on "tomorrow" but rather on "Japanese club". If included, it would imply that there's something particular about tomorrow, and maybe a bit of contrasting feeling as well.

As for けど, it seems it can also act as a "context particle" in that it provides some background before introducing the 行く？ question.