Caveats of using MaStar data.
Spectra usage caveats
- This is not a caveat: please note the wavelengths for the spectra are given in vacuum.
- The MaStar spectra are NOT corrected for foreground dust extinction. Reddening estimates based on 3D dust map and Gaia distance estimates are provided in the MaStar Crossmatch VAC.
- All spectra have been corrected to the restframe according to the reported heliocentric velocity (HELIOV), regardless of whether the HELIOV derived is robust or not. A velocity measurement is considered bad if its uncertainty is larger than 10km/s or if we encountered error during the fitting. All visits with bad velocity measurements have V_ERRCODE set to 1 and have the BADHELIORV bit (bit 6) flagged in MJDQUAL. They were removed from the list of good quality spectra, i.e. excluded from the GOODVISITS table and the goodspec file. If you are only using the good quality spectra listed in GOODVISITS table, you do not need to worry about this.
- The spectral resolution varies with wavelength. The resolution array is given along with each visit spectrum. We provide a description of how to deal with the changing resolution in Yan et al. (2019).
- The spectra do NOT have the same spectral resolution array --- they differ from spectrum to spectrum. The multiple visit spectra for the same star also can differ in their resolution arrays. We provide several subsets of spectra convolved to the same resolution curves. See the MaStar Spectra page for details.
- A small fraction of the good quality visit spectra still contain emission lines. These could either come from HII regions around the star or from stellar flares. These can be identified as having bit 8 (EMLINE) set in the MJDQUAL flag (see the bitmask table for MASTAR_QUAL here).
Caveats about Photometry
The Pan-STARRS1 (PS1) photometry we provided in the PSFMAG column for a small fraction of stars are unreliable and come from an outdated calibration. We recommend using the MaStar Crossmatch Value-added Catalog for the photometry information, which provides Gaia, Pan-STARRS1, and 2MASS photometry for all sources that have a match with each of these catalogs and uses the latest calibration available.
- MaNGAID 3-148801340 is a galaxy.
- MaNGAID 4-11104 is a galaxy.
- MaNGAID 4-15433 is a galaxy.
- MaNGAID 3-149429410 is a galaxy.
- MaNGAID 3-160736984 is a QSO.
- MaNGAID 60-2610821803610405504 is a Seyfert galaxy.
- MaNGAID 60-2267141475522684928 is a QSO.
- MaNGAID 60-1649991749245329152 is a QSO.
Stars with more than one MaNGA-IDs
Most of the time, each unique MaNGAID represents a unique star. However, a small number of stars were targeted under multiple MaNGAIDs. This file provides a list of stars that have more than one associated MaNGAIDs. Each row of the file lists the multiple MaNGAIDs that belong to the same unique star. There are a total of 154 such cases, involving 172 MaNGAIDs. Most of these cases involve standard stars. Sometimes, the same standard star was selected from different targeting files. At other times, the same star was observed as a science target by MaStar on one plate but also observed as a standard star on another plate (either MaNGA or MaStar). In 9 cases, the same star was targeted twice as science targets under different MaNGAIDs. If one pre-selects only good stars that are also science targets, then only the following 7 pairs are of concern.
- 3-133735849 is the same star as 60-604767752175631744
- 3-134064467 is the same star as 4-823
- 4-17885 is the same star as 4-840
- 4-12664 is the same star as 3-95914294
- 3-42209367 is the same star as 7-25771864
- 4-21098 is the same star as 4-20929
- 4-20872 is the same star as 4-20905
One useful tip for identifying these stars with multiple MaNGAIDs is to use the MaStar crossmatch catalog with Gaia EDR3. The same star would have the same Gaia SOURCE_ID. By finding entries with unique Gaia SOURCE_IDs, we can locate all unique targets. Note a small number of stars have no match in Gaia EDR3 --- but there are no cases among them that correspond to multiple MaNGAIDs.