BOSS Target Selection
Target selection is the process of selecting objects from the imaging survey for spectroscopic followup.
Target Types
In BOSS there are four types of targets, which are described in more detail at the following links:
Target Runs Used in BOSS
A target run specifies both a target software
version and a version of the data reductions. The following table contains
information for the various runs of the targeting code. The tag version is
marked BOSSTARGET_V
.
For information on tiling chunks, see the tiling page.
Target Run | Version Info | URLs | Comments | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
main016 |
|
QSO ngc targets
QSO SGC targets |
QSO bonus chunks boss29-*. |
||||||||||||
main015 |
|
QSO SGC targets | QSO chunk boss28 | ||||||||||||
main014 |
|
QSO NGC targets | QSO chunk boss24-boss27 | ||||||||||||
main013 |
|
QSO NGC targets
QSO SGC targets |
QSO chunk boss19-boss23 A trunk version of idlutils was used but this has no affect on the targets |
||||||||||||
main012 |
|
QSO NGC targets
QSO SGC targets |
QSO chunk boss18 These targets were actually bootstrapped from main011 due to some disk failures at LBL. |
||||||||||||
main011 |
|
QSO NGC target file QSO SGC target file |
QSO chunk boss17 | ||||||||||||
main010 |
|
QSO NGC target file QSO SGC target file |
QSO chunk boss16 These files include targets selected using multi-epoch photometry, when available. First chunk where new UKIDSS information is also included in the ExD processing when available, which is in turn used in the NN combinator. |
||||||||||||
main009 |
|
LRG target file |
LRGs for chunk boss15-* targeted from this run. This differs from main008 in the limit ifiber2mag - extinction < 21.5 |
||||||||||||
main008 |
|
QSO NGC target file QSO edfinal QSO SGC target file LRG target file |
LRG chunks boss12-boss14 QSO chunks boss12-boss13 using "sgc40" subset. QSO chunk boss14 using "edcore-maskngc40" and bootstrapped from main008 using code in BOSSTARGET v2_0_12. This file was mistakenly used instead of edfinal-maskngc40; edcore is actually trunk but has the same targets. Should reference edfinal in the future. QSO chunk boss15 uses subset file edfinal-maskngc40 STD chunks boss12-* |
||||||||||||
main007 |
|
LRG target file |
LRGs for Chunk boss7-boss11 targeted from this run. |
||||||||||||
main006 |
|
QSO NGC target file QSO SGC target file |
Chunk boss7-boss10 QSOs targeted from this run. ngc, masked for bad u data. Subset file "maskngc", which masks out the bad u-band data, was used for boss7 but this is not *stated* in the plan-boss7.par file. Subset file "masksgc1" was used for boss9 Unlike "maskngc", this does not mask out bad data, but rather restricts to a smaller chunk of the SGC. Subset file "maskngc" was used for boss10. In principle "maskngc" should have been used for boss8 but I think it was not needed since the target area was further north than the "bad" u data runs. Confirm? |
||||||||||||
main005 |
|
QSO target file LRG target file STD target file |
For QSO,LRG chunks boss5+boss6 targeted from this run. For STD chunks boss5-boss11 targeted from this run. No cut on calib_status. Full survey available at that time. |
||||||||||||
main004 |
|
STD target file |
Chunks boss3+boss4 STD targeted from this run. |
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main002 |
|
QSO target file LRG target file |
Chunks boss3+boss4 QSO and LRG targeted from this run. No cut on calib_status. |
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comm2 |
|
QSO target file LRG target file STD target file |
Chunk boss2 LRG+QSO+STD | ||||||||||||
comm |
|
QSO target file LRG target file STD target file |
Chunk boss1 LRG+QSO+STD |
Targeting Software
Targets lists for galaxies, quasars and standards were generated using
a unified software framework bosstarget
.
This code can be checked out from the svn repository
svn export http://www.sdss3.org/svn/repo/boss/bosstarget/tags/{tag} bosstarget-{tag}
Where {tag}
represents a "tagged" version of the code. Targets
used for BOSS spectroscopic followup are always generated using
a tagged version of bosstarget
To run the code, make sure the PHOTO_SWEEP
environment variable
points to the location of your copy of the datasweeps
Similarly, make sure PHOTO_RESOLVE
points to the relevant
resolve files and
PHOTO_CALIB
points to the relevant calib files.
Then the following IDL commands will execute targeting for a particular set of imaging runs and camcols
IDL> bt=obj_new('bosstarget') IDL> bt->self->process_runs, target_type, target_run, $ runs=runs, camcols=camcols
where target_type
is 'lrg','qso','std' and target_run
is an arbitrary string. There are more options documented in the code. The
->process_partial_runs
method can be used to process a set of
runs. The targets can then be collated into a single file using
->gather
or the partial sets using ->gather_partial
.
After the collation, appropriate BOSS_TARGET1 flags can be applied to limit to a smaller subset of targets.
For QSOs a further trimming is applied in order to limit the target density
to 40/sq degree in "cells" on the sky. This code is in
/pro/bosstarget_util.pro
in the ->subreg_density_tune
.
Variability Selected Targets
The variability selected catalog used for quasars in chunk boss11 is described in Palanque-Delabrouille et al. (2011).