A little SF vignette

Canada has these laws that require a certain fraction of the music that is broadcast to be Canadian. This caused a certain amount of screaming from radio stations, but I have this feeling that it actually works, that Canada as a result produces disproportionally more music, and more original music. I don't know about that (how would you quantify it?), but this band — You Say Party — is Canadian.

arXiv gleanings

I try to keep an eye on arxiv.org because interesting new pulsar papers generally appear there first. But there are often abstracts that catch my eye, whether because they have neat ideas, because they talk about neat object, or because they just seem peculiar. This week's batch had a few of each.

How tempo2 does its fitting

Pulsars can be difficult objects to study: for example, their radio pulses can randomly change in brightness, turn off, turn on, change shape, and we really don't know why. Nevertheless there has been some excellent science done by studying those very radio pulses. The trick has mostly been to simply not care how bright they are or what shape they have and focus on when they arrive. Since this comes from the rotation of the pulsar, this tends to be very regular. After all, for a ball 10 km across, with more mass than the sun, smoothed to within a millimeter by its own gravity, it takes an awful lot to change how fast it's spinning. What's more, time is the quantity we can make the best measurements of - world time standards drift by something like microseconds over decades, which is something like one part in ten to the fourteen. So pulsar timing is a powerful technique, that can measure pulsar positions and distances, spin-down rates and braking indices, and binary orbits. The standard software has been tempo, which is written in FORTRAN and has certain limitations. A new tool has recently appeared, tempo2, written in C++ and boasting good handling of timing effects down to the nanosecond level. Unfortunately the documentation on this tool is so far somewhat limited, so I've been figuring out how it works. I'd like to describe it, as best I understand it, here. This particular post will talk about how a timing solution is fit to a set of pulse arrival times.