survey the entire sky subject to a sensitivity of $m_{AB}$$\sim$ 20.5, and the Medium Imaging Survey (MIS), which covers 1000 deg$^2$ with extensive overlap of the SDSS (Martin et al. 2005; Morrissey et al. 2007).

We use the CASJobs[^5] to match our SDSS-2MASS sample with the GALEX GR4/GR5 database by importing coordinate list and then obtain their magnitudes in FUV and NUV (see the help in website[^6]). Firstly, we import a prepared coordinate list into the database, which is for the RA and DEC of our SDSS-2MASS matched sample. Then a new table of this is created in the database. Next we search for neighbors for the objects within a radius of 5$^{\prime \prime }$, and then obtain a new table of GALEX-matched objects which provide the unique GALEX object identifier (objid) as matched\_id, and also the search\_id to mark which original object it corresponds to. In the case of multiple matches, we choose the nearest one with minimum matching distance. Finally, we obtain the magnitudes, fluxes and their errors for these objects. We use the GALEX products given in the “-mcat.fits" file, which is the Merged (FUV+NUV) source catalog. We adopt “nuv\_mag" and “fuv\_mag" (and their errors) as the 