AS4 stellar astrophysics concept

Science scope:
  broad spectrum of ground-breaking stellar astrophysics,
 telling us how stars work, live and die...

With Gaia & TESS there are transformational space missions 
that focus on imaging/photometry/astrometry (some spectra) of bright stars.
The proposed program is tailored towards a spectroscopic survey that
in many ways ideally complements this:
 -- it is all sky
 -- it is matched in apparent magnitude
 -- it is time-domain
 -- it is dust-penetrating (disk/young stars)

Natural operational meshing of stellar astrophysics & DISCO

It is focussed on
 -- age-chemo-orbital mapping of the entire galaxy 
 -- binary stars across the HR (as calibrators, stellar evolution, SF,SN)
 -- astroseimsology to understand stellar evolution (need spectra)
 -- planet hosts 

It is a full sky program, with APOGEE and BOSS (1 each) in both hemispheres,
2/3 is multi-epoch observations; 2/3 APOGEE; 1/3 BOSS; still based on a 10min minimal cadence.

"Surprise" element:
Instead of a ROBOT, a 4-5 fold-set of 300 APOGEE fibers, feeding 4-5 gang connectors,
still using plug plates would enable:
 -- simultaneous use of 300 APOGEE and 500 BOSS fibers 
     --> better use of instrument/detectors
 -- more flexibility in fiber placement

This would mean:
-- minimal new hardware development 
   (RV improvement; fiber cart upgrade with BOSS and more APOGEE fibers)
-- move 1 BOSS spectrograph to LCO
-- plug plate costs in two hemisphere continues
-- could start 2019

All science can be done in minimally 3 years; comfortably 4 years;
minimum 25 Million x 10min x spectrum
few million fiberx10min open (for BOSS)

Much of the same science would work within fiber-robot framework,
too, in comparable survey duration.