My Hebrew after decades of non-use being almost non-existent I seemed to remember a fast of a similar name. The dictionary proved you right on both counts: It is a wee time before sunrise and it is part of the Jewish law (halacha). Having learnt my lesson ocncerning gegenschein I tried google and came across a certain Rabbi Doniel Neustadt (http://www.torah.org/advanced/weekly-halacha/5761/balak.html)
who explains it a lot better than I ever could.

haslacha to you - spelt with an s » success, succesful outcome
Hans-Hermann