High-Quality Galaxy Spectra

Summary

Repeat observations of two spectroscopic plates, leading to higher signal-to-noise spectra for 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. Thus, rather than searching for a specific value of ANCILLARY_TARGET1, finding these spectra requires only searching for specific plate numbers.

All spectra on plates 3615 and 3647 are part of this Ancillary Target program. Each plate corresponds to 1,000 unique objects. Plate 3615 was observed six times, resulting in 6,000 spectra. Plate 3647 was observed eight times, resulting in 8,000 spectra. The table below gives information about each observation, indexed by plate number and MJD.

Plate Center RA Center Dec MJD Date observed
3615 37 0 55179 14 Dec 2009
3615 37 0 55208 12 Jan 2010
3615 37 0 55445 6 Sept 2010
3615 37 0 55856 22 Oct 2011
3615 37 0 56219 19 Oct 2012
3615 37 0 56544 9 Sept 2013
3647 37 0 55181 16 Dec 2009
3647 37 0 55241 14 Feb 2010
3647 37 0 55476 7 Oct 2010
3647 37 0 55827 23 Sept 2011
3647 37 0 55945 19 Jan 2012
3647 37 0 56219 19 Oct 2012
3647 37 0 56568 3 Oct 2013
3647 37 0 56596 31 Oct 2013

Description

Two plates (3615 and 3647) were 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 more than 800 hours of total spectroscopic exposure for all targets on these two plates between December 14, 2009 and October 31, 2013. The complete observations result in high signal-to-noise spectra, which will enable detailed spectral population studies of intermediate-redshift LRGs. The data also provide a platform for tests of the consistency in spectroscopic parameter extraction (e.g., Shu et al. 2012, Thomas et al. 2011), and of systematic errors in the models of continuum fitting in the Lyman-alpha forest region of the quasar sample (e.g. Lee, Suzuki, & Spergel 2012).

REFERENCES

Shu, Y., et al. 2012, AJ, 143, 90, doi:10.1088/0004-6256/143/4/90