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High-Quality LRG Spectra


Repeat observations of two spectroscopic plates, leading to higher signal-to-noise spectra for about 2,000 luminous red galaxies

Finding Targets

This Ancillary Target program works differently from the other programs. Rather than assigning some number of spectra on each plate as ancillary targets, this program used the entirety of two plates.

All spectra on plates 3615 and 3647 are part of this Ancillary Target program.

Plate Plate center Date of observations MJD Link to data Target density
3615 ra=37°, dec=0° Dec 14, 2009 55179 3615/55179 333
Jan 12, 2010 55208 3615/55208 333
Sept 6, 2010 55445 3615/55445 333
3647 ra=37°, dec=0° Dec 16, 2009 55181 3647/55181 333
Feb 14, 2010 55179 3647/55241 333
Oct 7, 2010 55476 3647/55476 333


Two plates (3615 and 3647) are being observed repeatedly throughout the survey, several times per year. The goal of these repeat observations is twofold: to test the reproducibility of spectral parameters extracted by the spectral pipelines, and to create deep spectra of a subset of objects in the main BOSS sample.

Spectroscopic observations of targets in this ancillary target program will produce accumulated exposure times of more than 20 hours each for all targets, including 96 LOZ and 503 CMASS LRGs at α = 37 degrees on Stripe 82. The plates contain identical spectroscopic targets, but are drilled for different airmasses.

The survey acquired 16.5 hours of total spectroscopic exposure for all targets on these two plates between December 1, 2009 and July 15, 2011. Observations will continue in each of the three remaining years of the survey. The final observations will produce high signal-to-noise spectra, which will enable detailed spectral population studies of intermediate-redshift LRGs. The will data also provide a platform for tests of the consistency in spectroscopic parameter extraction (e.g., Shu et al. 2012, Thomas et al., in prep.), and of systematic errors in the models of continuum fitting in the Lyman-alpha forest region of the quasar sample (e.g.; Lee et al., in prep.).


Shu, Y., Bolton, A. S., Schlegel, D. J., Dawson, K. S., Wake, D. A., Brownstein, J. R., Brinkmann, J., & Weaver, B. A. 2012, AJ, 143, 90, doi:10.1088/0004-6256/143/4/90