Large Sky Area Multi-Object Fiber Spectroscopic Telescope

DR2 UPDATE (20151215)

Several problems have been found and fixed since last DR2 update. All of the spectra and catalogs here have been modified according to the latest updates, which are shown as follows:

1) 11 fibers’ IDs were found being wrong. We investigated all of the sky spectra assigned to these 11 fibers and finally determined the date when those mistakes happened. Among them, IDs of 9 fibers were found having been wrong since the begining of survey in 2011, and 2 of them happened during the replacing of bad fiber units in the summer of 2013.

We have fixed this problem by reassembling the affected spectra to the corresponding parameters, both in the catalogues and fits files. Total number of affected spectra is 7758, including 6640 changed and added, and 1118 removed by the flags such as position_error, etc. Here we provide a list of affected fibers and lists of changed and removed spectra.

2) There were some mistakes in calculating MJD (both fits header and catalogs), so we modified these values of MJD in this new version. Also we note that all fits files (spec) are named as spec-MMMMM-YYYY_spXX-FFF.fits where ‘MMMMM’ represents the local modified Julian day (LMJD).

3) The velocity of some M star spectral templates was found incorrect, which were applied to calculate the radial velosity of M stars. Therefore, ‘rv’ and ‘rv_err’ of all M stars have been recalculated with Hammer M star spectral templates in this update.

4) Minor fixes to the value of keywords ‘objtype’ and ‘tcomment’ of certain spectra in the catalogues.

5) Supplement 566 spectra of stars, which were mistakenly omitted by eye-check due to the plot problem in original DR2. Here we give a list of these stars.

6) Supplement 295 spectra of galaxies, which was the results of redoing eye-check required by users. Here we give a list of these galaxies.

7) Remove 4666 spectra, which were flagged as ‘fiber position error’, but being ignored by pipeline during the early days survey. Here is a list of these spectra.