APOGEE DR12 Status/Discussion

Schedule

• Nominal DR12 deadline is July 31, i.e. tomorrow• SDSS-III upper level management was consulted

about a small delay to take advantage of feedback from this meeting. Adam Bolton:– “From July 31 to August 31, the schedule impact of

this goes more or less linearly from "no big deal" to "we're totally hosed". By "we're totally hosed", I mean that we will be forced to choose between either leaving APOGEE out of DR12 CAS or delaying the whole of DR12 significantly.”

• Practical deadline perhaps 8/15

DR12 products to be delivered• SAS

– All raw and intermediate data files– Final summary: allStar, allVisit files

• Data model for parameters/abundances: – FPARAM, PARAM, TEFF, LOGG – FELEM, ELEM (in native FERRE) + X_H

• SASDB (allows web/API interface to SAS files)– Populated from apField, aspcapField files

• CAS– Datamodel for abundances: translate arrays into prefexed parameters, have named

parameters for TEFF, LOGG, abundances• FPARAM_TEFF, FPARAM_LOGG, FPARAM_M_H, etc., PARAM_..., TEFF, LOGG• FELEM_X_[MH], ELEM_X_[MH], X_H, ….

– Populated from allStar, allVisit files• DR12 web pages• Datamodel complete and up-to-date

Focus: key issues

• Current set of files exists– Reduction/star combination final (?!)– ASPCAP will be rerun, but test files exist for proposed final run– Files need to be checked for datamodel, implementation errors/issues

• Is there anything significantly wrong with basic contents of current files: bar needs to be high to modify significantly (OK to modify calibration decisions)

• Issues– Calibrations to apply– Flags to apply– Discussion/documentation issues:

• What do we say about quality/usability for individual elements• Unexpected abundance trends in some elements• More S/N sensitivity than expected

Scope/analysis• New reductions of all data taken to date

– Reduction version r5 has improved telluric, etc.– Includes apo25m commissioning/survey + apo1m

• ASPCAP analysis– ASPCAP configuration l23

• December 2013 linelist (not quite latest: incorrect treatment of Sun when deriving astrophysical gf)

• ASSET synthesis using solar isotope ratio• Same grid dimensions/spacing as DR10• lsfcombo5 LSF: average of fibers 50,100,150,200,250• speclib bundling of libraries

– 7d analysis of calibration subsample (parameters only), from which logg-vmicro relation is derived to construct 6d library

– 6d library run on calibration subsample– Calibrations derived from 6d results of calibration sample– 6d library run on full sample, applying calibrations

microturbulence

• Proposed relation: linear fit as f(log g)– Similar to DR10 relation– Dwarfs are hitting bottom edge of

microturbulence dimesion– Fit derived from giants only

• Cluster parameters appear very similar using adopted relation

Calibration

• Raw ASPCAP data probably needs to be “calibrated” for some quantities– DR10: calibrated Teff, logg, [M/H]

• DR12 proposal– Teff: calibrate using photometric (GHB) temperatures for stars with

well-measured extinctions/temperatures: functional dependence?– Logg: calibrated using Kepler sample of RGB stars, as f(log g)– Other “intermediate” parameters: no calibration– Elemental abundances:

• “internal” calibration: correction as f(Teff) to minimize trends of abundance of each element within clusters (no C or N)

• “external” calibration

– Attempting to have all data/routines used for calibration archived within SDSS software product idlwrap

Teff calibration

• TBD

Log g calibration via Kepler asteroseismic gravities

Abundances: internal calibration

• Small trends of abundance with temperature seen for some elements within clusters

• Propose to fit this trend with metallicity-dependent slope– Linear relation– Slope frozen outside of specified metallicity range

• Is this a good idea?– Is linear trend OK?

Cluster plots

Full sample plots

Uncertainties in abundances

• Propose to fit scatter within clusters as f(Teff,[M/H],S/N) with linear relations, truncated outside of calibration range

• Needs checking• Need decision on “raw” uncertainty

computation from FERRE; do any options provide meaningful errors in regimes of large uncertainty (e.g. non-detections)?

Abundances: external calibration

• Challenge: lack of external calibration samples for individual elements

• [Fe/H] suggests trends similar to those seen in [M/H] for DR10: relatively accurate around solar but off by ~0.2 dex at low metallicity– Should we correct this?– Issue: if we correct [Fe/H], then when people look at

[X/Fe], they will all be shifted at low metallicity – What to do for other elements?

• External cal plots

DR12 products• SAS

– All raw and intermediate data files– Final summary: allStar, allVisit files

• Data model for parameters/abundances: – FPARAM, PARAM, TEFF, LOGG – FELEM, ELEM (in native FERRE) + X_H

• SASDB (allows web/API interface to SAS files)– Populated from apField, aspcapField files

• CAS– Datamodel for abundances: translate arrays into prefexed parameters, have named

parameters for TEFF, LOGG, abundances• FPARAM_TEFF, FPARAM_LOGG, FPARAM_M_H, etc., PARAM_..., TEFF, LOGG• FELEM_X_[MH], ELEM_X_[MH], X_H, ….

– Populated from allStar, allVisit files• DR12 web pages• Datamodel complete and up-to-date

Work session

• Task list for checks• Summary files: allStar, allVisit

– Compare uncalibrated vs calibrated (calibrations applied correctly?)

– Play with all quantities!• DR12 documentation

– All pages up-to-date– Description/discussion of abundances

• Datamodel– Complete and up-to-date? – All SAS files should be in datamodel: but start with most important

ones!

Other open issues

• Hot stars: hot grid not currently implemented; F grid goes to 8000, but with 6D fits

• Low metallicity stars• Dwarfs: generally poor results

Other versions

• V304 (DR10)• V402 (DR11): extend DR10 to year 1+2, flat

files have first cut at 9 elements• V500: first cut 15 elements• casset: new version synthetic libraries with

self-consistent atmospheres• l22_6d: new reductions• v600 (DR12): with calibrationsdr12