didn't find a stream, LSR doesn't exist

Lang and I switched to brute-force foreground/background modeling, after Koposov convinced us it was a good idea and we convinced ourselves that we could do it quickly (see yesterday's post). We found a stream, very near the Sun! Then we scrambled the data (that is, generated fake data that can't have structure) and found even more streams, so I guess we didn't really find a stream. Working on it.

Behind us in the office, Bovy has been working on the Sun's motion relative to the local standard of rest. The assumptions that underly the measurement of the LSR are all violated; is there an LSR at all? We don't know (there doesn't have to be one at all if the Galaxy isn't close to axisymmetric), but we do know that if you assume there is a local standard of rest, what you get for it is a strong function of how you deal with stars that are members of the cold moving groups in the disk. The error bars in the literature, including mine in Hogg et al 2005 are all way underestimates.

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