On Sat, Feb 20, 2016 at 12:27:42PM +0100, Knapp wrote:
> Once you get a couple of flashes from 3 points then you can
> triangulate where the ship landed. You know that the flash is at
> least a couple of hundred years old, light speed, so it should be
> people free.

The inverse square law hurts too much for this.

With a huge sensor array, and a favourable rule set, you might pick up
some jump flashes from a light-month out (5000 AU).  More normal
starship sensors are only going to detect them out at a light-day
(about 200 AU) if they're lucky, and even then have trouble
distinguishing them from noise (i.e. require a good roll on the
appropriate skill).

Half a parsec is 100 000 AU.  To have a good chance of detecting a
misjump in a cubic parsec, you would need about 20 000 huge sensor
arrays (each much larger than a normal starship's sensors).  After a
month, the flash energy will be too diffuse to pick up by any
reasonable sensors.

> I think this could lead to some interesting adventure possibilities.

More likely is the possibility of picking up tightbeam directed
distress calls.  An omnidirectional distress beacon won't have a hope
of being picked up, but if the crew can beam a collimated signal with
high power directly at an inhabited system (e.g. using weapon lasers),
that could be detected.  Very easily, actually.

If in visible light, the smallest starship laser pulse from a parsec
away could outshine Venus at its brightest, with a flash bright enough
to leave an afterimage.  It would have to be aimed rather well; the
primary beam would only be a few planetary diameters wide.  It might
be better to deliberately defocus at least some of the pulses so as to
cover the whole inner system, just in case you missed with the most
tightly focussed ones.

- Tim