Extreme Variability Quasars Catalog from SDSS DR16Q

We provide all 20,069 available spectral measurements of 14,012 EVQs selected in Ren et al. 2022. Repeated observed spectra of a same EVQ will have the same SDSS NAME with different spectral info (PLATE,MJD, and FIBER). We include the SPECPRIMARY flag to indicate if the spectrum is the best observation of this object. The unmeasurable parameters are set to -9999. The errors are obtained from 100 iterations of Monte Carlo simulation.

We extend my heartfelt gratitude to our Data Editor of the AAS Journal, August Muench, for his invaluable assistance in the data verification and MRT format compilation of this dataset. His expertise and meticulous attention to detail were instrumental in enhancing the quality and accessibility of this work.

We note that, in most cases, all measurements in a same line complex would be either all null or all valid, however, there exist some exceptions.

In our dataset, there are generally two scenarios lead a measurement to the null value (-9999).

The most frequent case is due to the spectral coverage. When a emission line region is not measureable, we will set the whole relavent value to null.

Besides, there are some exceptions that we do have a real fitting but still can not give a reasonable measurement for some specific elements.

For any line component with FLUX==0, we reserve the FLUX and EW of this line to 0 but change the rest measurements (FWHM, PEAK, etc.) to -9999.

For double peak broad component, we set the line FWHM/FWQM/FW10M and their corresponding center shifts (Z50/Z25/Z10) to -9999

In addition, since the systematic shift is relatively minor feature of a line, spectra with very low S/N ratio can not well constrained the line shape. User could find a bunch of lines with Z50/Z25/Z10 == 0. Nevertheless, in those cases, their error would be extremely high indicating that measurements could be unreliable.