This page relays a list of known issues in the APOGEE data release.
Methodology and Data Limitations
Incorrect LSF for some LCO stars
For the initial ASPCAP run using the synspec grid, a bookkeeping error was much such that some of the LCO stars were processed using a non-optimal LSF grid, as it used the APO fiber LSF assignments rather than the LCO fiber assignments. This leads to small, but not negligible, changes in derived stellar parameters and chemical abundances for about 113,000 stars from LCO.
The affected LCO data have been reprocessed using the correct assignments and a corrected version of the files are found in the Science Archive Server under the synspec_rev1 directory tree; the revised summary file is allStar-dr17-synspec_rev1.fits
We recommend users adopt the synspec_rev1 results, but note that there will be inconsistencies with the subset of Value Added Catalogs that adopted stellar parameters and/or chemical abundances from the initial synspec run, which are found in the synspec file directory.
Lingering effects of LSF
Erroneous extinctions for bright stars
Users are cautioned against using the tabulated extinctions for very bright stars.
Persistent effects of persistence
Users of the APOGEE spectra should pay careful attention to the persistence flags and should consider the use of the inflated uncertainties for persistence-affected pixels.
Atypical Abundance Ratios
The Abundance Scale
SNREV, that is determined over a wavelength region in the middle chip that should not have many pixels that can be affected by persistence.
SNREV is the recommended quantity to use for S/N assessment.
Rotation in Giants
Problems and Bugs
VHELIO is in Barycentric Frame
Incorrect telescope values in some LCO FITS headers
Inconsistent Population of Named Tags
M_H_BADflag set should have their named tag abundances unpopulated, however there are some stars who have this flag set and some populated named abundance tags.
We advise those using named tag abundances to check if the
M_H_BAD flag is set, and if it is set to treat such abundances with caution.
This section contains items unique to APOGEE-2 processing. Caveats and issues with APOGEE-1 observations are documented here.
Multiple target classes
ORof all of the target flags of the individual visit spectra. As a result, there are stellar spectra constructed from multiple visits for which a target flag bit may be set in the combined spectra, but not in all of the visit spectra that were used to construct it.
Users modeling the selection function for APOGEE-S data are encouraged to check the field-of-view for the plates used in their analysis.
EXTRATARGbitmask that appears in the summary allStar file and in the CAS table.
EXTRATARG bit should allow users to avoid the duplicate use of the same target in an analysis.
TELESCOPEof "apo1m"), alternate object names were used for observation and reduction. 2MASS identifications, however, have been adopted in the final summary files and associated database tables. If users want to find the individual star spectrum files (e.g., the apStar or aspcapStar files), they will need to know the star name used during the reduction, which is stored in the
Users should check the
ALT_ID tag before seeking individual spectrum files for NMSU 1-meter observations.
Targeting Flag for 1-meter data
APOGEE2_TARGET2bit 22 was not set in DR16. The 1-meter data can still be isolated using the
Users should identify 1-meter data using
telescope = 'apo1m' instead of using