fiber mapper

I did some writing in three places: I worked on my Roweis reminiscence; I put together a straw man proposal for taking Bayesian exoplanet analysis to meta-analysis, with hyper-priors and simultaneous fitting of all planets; and I wrote an email to the SDSS-III BOSS collaboration about fiber-mapping (the determination of which fiber on the slit-head is plugged into which hole in the focal-plane plate). That email contained the following summary and introductory paragraphs of that email:

executive summary: If ever we needed to replace the fiber mapper system, there is a simple system we could build that maps all of the fibers with a single read of the science CCDs, obviating the need for a fiber-mapping hardware system that is independent of the science camera, and obviating the need for a large part of our cross-system meta-data maintenance. The system works by projecting non-degenerate patterns—a different one for each of a set of optical wavelengths—on the focal plane. The set of wavelengths "seen" down each fiber is then a unique (invertible) function of position.

historical note: On January 17th, at the memorial for Sam Roweis here in New York, Finkbeiner (Harvard), Eisenstein (Arizona), Lang (Princeton), Hogg (NYU), and Mierle (Google) had a late-night conversation about spectroscopy in which Mierle (engineer, worked on astrometry.net data structures and worlds-fastest kd tree) asked how the SDSS spectrographs work. After a few minutes of introduction, Finkbeiner challenged him with the fiber-mapping question and Mierle produced this idea, more-or-less. What I say below is based on refinements of the idea that happened around the table that night and in conversations after. I am sorry to be so slow to transmit this to the collaboration, but I guess since we have a working fiber-mapper, this is not urgent!

[Detailed proposals follow this in the email but are too boring to repeat here; email me if you want the full text.]