# MaStar Spectra

The spectra for all the good quality visit spectra can be accessed easily through the summary spectra file or individual spectra files.

### Summary Spectra File

The mastar-goodspec-[version].fits file is available on the Science Archive Server at this link.

The file size is approximately 1 GB. We recommend using rsync to download the file, see the command on the Data Access page.

The naming convention is mastar-goodspec-[version1]-[version2], where [version1] and [version2] are the versions of the pipelines used to produce the file. [version1] is the version for the MaNGA Data Reduction Pipeline (v2_4_3 for DR15) and [version2] is the version for the MaStar post-processing pipeline (v1_0_2 for DR15).

The data model for the mastar-goodspec file is available here.

All of the high-quality spectra obtained for the MaStar targets are presented in this file. This file only includes the visits that were determined as high quality. This corresponds to the second extension ("GOODVISITS") of the mastarall summary file.

Each entry in the mastar-goodspec file contains the 1D spectrum (with wavelength given in vacuum), identification, and observation information for a star from one night of observation, called one "visit". If a star has been observed on multiple visits, then there will be multiple entries for that star. Spectra from multiple exposures on one night have been combined together to give a single visit spectrum of the star for that night.

Spectral quality information is contained in the "MJDQUAL" flag, which follows the MASTAR_QUAL bitmask scheme. This provides quality information about the spectra. Here we list the meaning for each bit in the MASTAR_QUAL bitmask scheme.

Bit name Binary digit Value Description
NODATA 0 1 No Data. (Never set in the current pipeline)
SKYSUBBAD 1 2 Bad sky subtraction in one or more frames. (Already excluded from the GOODVISITS table.)
HIGHSCAT 2 4 High scattered light in one or more frames.
BADFLUX 3 8 Bad flux calibration. (Never set in the current pipeline)
LOWCOV 4 16 PSF-covering fraction by fiber is too small (<10%). (Already excluded from the GOODVISITS table.)
POORCAL 5 32 Flux calibration affected by incorrect extinction estimates. These spectra are not visually inspected. (Already excluded from the GOODVISITS table.)
BADHELIORV 6 64 High variance among stellar radial velocities derived from all exposures. Only possible to judge for stars with more than one exposures.
MANUAL 7 128 Flagged as problematic by visual inspection. (Already excluded from the GOODVISITS table.)
EMLINE 8 256 Spectrum contains emission lines.
LOWSN 9 512 Per-MJD Spectrum has median S/N <= 15. (Already excluded from visual inspection and the GOODVISITS table.)
CRITICAL 30 1073741824 Critical failure in one or more frames. (Never set in the current pipeline.)

This file does not include stellar parameters or information from the input (targeting) catalogs. That information is provided in the mastarall file.

### Individual Spectra

Individual 1D spectra are also available through the Science Archive Server:

https://data.sdss.org/sas/dr15/manga/spectro/redux/v2_4_3/[PLATE]/mastar/mastar-LOG-[PLATE]-[IFUDESIGN].fits.gz

Where [PLATE] is the plate number and [IFUDESIGN] is the ID of the fiber bundle used to target this star.

The data model for the mastar 1D spectra file is available here.

These files have 3 extensions:

1. MASTAR: Combined spectra for each night of observation. Individual exposures from each night were combined together to give a single spectrum of the target for that night.
2. OBSINFO: Observation information (airmass, seeing, PSF, etc.) for each individual exposure.
3. FITDETAIL: Individual exposure spectra.

In the MASTAR extension, the quality information is given in the MJDQUAL column. In the FITDETAIL extension, the quality information is given in the EXPQUAL column. In the header of the primary HDU of this FITS file, there is a keyword called "MSTRQUAL" that provides a summary quality information for this star. All of these follow the MASTAR_QUAL bitmask scheme. The MJDQUAL of a given visit spectrum is the AND product of the EXPQUAL of all of the exposures contributing to that visit. The MSTRQUAL is the OR product of all exposures taken for a given [PLATE]-[IFUDESIGN] combination.