SEGUE Plates, organized by Program and Survey

Introduction

The SEGUE sample consists primarily of two surveys, SEGUE-1 and SEGUE-2, which in turn encompass various observational programs. Each program consists of a number of different 7 square degree plug-plates. When isolating a sample of stars from SEGUE, it is important to take into account the different programs. For example, if a particular line-of-sight was observed as part of the seglowlat program, it used different target selection criteria than one targeted as part of the segue program. Similarly, the different surveys vary in their observational focus. The survey and programname for each individual plate are listed in the PlateX table in CASJobs. For most SEGUE plates, survey will be segue1, segue2, or sdss. For later data releases, it could also be boss, marvels, or apogee.

Different Programs in SEGUE

The programname parameter gives information about both where and why a particular plate is targeted. The different programs in SEGUE-1 and SEGUE-2 are listed below:

Below we list the different plates in each program, in addition to their location on the sky, estimated extinction, and quality of the observations.

Program: segue, seguefaint

The plates under the program name segue are the bright plates from the segue1 survey. Corresponding faint plates are listed as seguefaint. These plates are placed without regard to known substructure. Note that not every bright plate has a corresponding faint plate. The target selection value listed indicates the algorithm under which the plate was designed. The quality parameter is determined by checking the S/N of stars with (g-r) color of old main sequence turnoff stars at a g of 18.

Program: segue2

The plates under the program name segue2 are slightly different than those from the SEGUE-1. Unlike the segue program, SEGUE-2 does not do both bright and faint exposures. As SEGUE-2 focuses on the distant Galaxy, it consists solely of deep pointings. Additionally, the target selection algorithm for the SEGUE-2 targets did not evolve in the manner of the SEGUE-1 program plates. Thus, we have not listed the Target Selection parameter here. Similar to SEGUE-1, the plates of SEGUE-2 are placed without regard to known substructure.

Program: segtest, segtestf

The plates under the program name segtest use a special target selection algorithm used for testing the overall SEGUE programs. When trying to make a uniform SEGUE sample, it is best to not use spectra from these plates. If you need the spectrum for a particular object, it is fine to use the observations.

Program: segpointed, segpointedf

Plates labeled segpointed were directed at the location of probable Milky Way substructure. They have corresponding faint plates, labeled segpointedf. Like segtest, these should not be used when creating a uniform SEGUE sample.

Program: segcluster, segclusterf

The plates under the program name segcluster are directed at both globular and open clusters. The spectra from these plate pairs, in conjunction with crowded field photometry from An et al. (2008), are a useful test for the SEGUE Stellar Parameter Pipeline as described in Lee et al. (2008) part I and part II, and Smolinski et al. (2010). Fibers from these plates are used to spectroscopically target cluster members. All fibers not devoted to the cluster are assigned to targets based on the target selection algorithm. However, because of the targeted structure, these plates need to be treated separately than others when accounting for target selection. In addition, due to the difficulty of deblending their photometry, many of these targets do not have associated photometry in any given data release (see Caveats).

Program: seglowlat, seglowlatf

Plates labeled as seglowlat, and their respective faint plates seglowlatf, are placed at low Galactic latitude. They have their own target selection strategy described briefly on the SEGUE Target Selection page.