I'm starting to play with the asteroids databases, and want to see if I can spot any with my 8" Newtonian scope. I've started plotting trails on them with XEphem, and notice that most of them seem to really be moving quite fast, so I'm going to have to find ones that pass close to a fixed point that I can train my scope on.
My question is this: Is there a way of searching for closest pairs other than saving the list out to a text file and doing some sort of 'grep' on it? Specifically, I have a reasonable amount of sky overhead, but am surrounded by trees, so in many directions, I can't see below 30-40 degrees, and in one spot, the redwoods block out half the sky, up to probably about 70-85 degrees. (I did just discover the 'xephem_hzn' file functionality, so I'm going to survey my treeline to have XEphem plot out what I can actually see.)
So what I'd like to do is be able to say "I can see Deneb. I'd like to be able to search for any close pairs that come within X.Y degrees of separation from Deneb." (Or whatever stars I can see in my sky at that time.)
It currently seems like the close-pairs functions just do a bulk search and give a list, sorted by separation. It'd be nice to be able to refine that search by some known stars, and to sort it in different ways (name, magnitude, etc.) Also, perhaps a way of searching backward and forward in time, to say "what things will be passing close to Jupiter tonight, during this 6-hour window?"
Elwood, are there any plans to do things like this? Or should I be breaking out the source code and trying to figure it out myself? I realize that I could do this simply in the shell with the text file output, but I'm not sure how I'd go about finding things that pass close to a known star or other point (planets, etc.) other than a haphazzard stumbling across it by accident.
Is there some other functionality that I don't know about within XEphem that lets you search like this? How do the asteroid occultation people figure out what events are going to happen, other than a brute-force search?
Keep up the great work, Elwood! :-)