changes by 0.21 mag.

Other Multiwavelength Data
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X-ray Observations
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UM 625 was observed by [*XMM-Newton*]{} on three separate occasions between 2004 and 2008 (ObsID: 0200430901, 0505930101, 0505930401) and once by [*Chandra*]{} in 2008 (ObsID: 9557). We used [*XMM-Newton*]{} SAS version 12.0.1 and the calibration file of June 2012 to reduce the EPIC PN (Strüder et al. 2001) archival data. After filtering background flares, the net exposure times are 6.4 ks, 13 ks, and 13 ks, respectively, for the three PN observations. The source was detected at a large offset angle ($\sim 10\arcsec -11\arcsec$) from the field center for the later two PN observations. To extract the source and background spectra, we defined the source region as a circle with radius $\sim 30\arcsec 
-40\arcsec$ centered at the source position and the background regions as three or four circles, far removed from the CCD edges and other sources, with radii $\sim 30\arcsec -40\arcsec$ around the source region. The [*Chandra*]{}  ACIS-S (Garmire et al. 2003) data were reduced with CIAO 4.4.1 (Fruscione et al. 2006) and the CALDB 4.4.10 database, adopting standard procedures. The net exposure time was 49 ks. Because of the large off-axis angle (106), we extracted the spectra 