M31 O-F Supergiant Stars Observed by GALEX

Using the OFSG list from Massey et al. (2006) we generated lightcurves from the GALEX epochs that cover M31. Most OFSGs are detected, but are in very crowded regions.

UV Photometry was performed using the IDL aper.pro routine in two passes. The first pass is used to decide if the object is detected and uses a 2 pixel radius measurment aperture. If the signal-to-noise ratio is greater than three, the object is considered detected. The detected objects are then measured again with a 1 pixel radius aperture (R=1.5") and the fluxes are corrected to full flux using the aperture corrections from Patrick's GALEX calibration paper. The sky annulus used in both passes is from 5 to 15 pixels. In the plots below the detected objects are plotted with a blue diamond (NUV) or a purple triangle (FUV), while the non-detections are plotted as limits with the corresponding color.

Optical Photometry was taken from the CCD UBVRI photometry reported in Massey et al. (2006).


OFSG UV Light Curves with Optical Photometry

The epochs of the GALEX images are indicated by the vertical dashed lines. If an object was off the edge of the image for a given GALEX epoch, it is indicated by a black plus-sign near the bottom of the plot. The title indicates the ID of the star, it's spectral type, and a cross identification if one exists.


Last updated, 06 Sep 2007

Please send questions or comments to Don Neill at neill AT srl DOT caltech DOT edu