It's a year ago today that my 'hard SF' story The Grey Hole was published. It doesn't seem that long, perhaps due to the time dilation effect of quantum singularities.
This was my first attempt at a 'hard SF' story, i.e. one where the technology is based more on science than on fiction. It was also the first time I set about writing a story of significant length. Previous stories had never made it to 2,000 words, and in those days, 12 years ago, the few markets that existed had 2,000 words as a minimum. I aimed for 5,000 words and finished up with 5,200.
It was accepted on its first submission, by Aphelion. I'm currently waiting to hear back from them about the sequel, The Grey Void.