– 8 – c. Are detected with signal to noise ratio > 7 in all 2MASS and IRAC wavelengths as well as at 24 µ m, to ensure we only include targets with very reliable photometry. This criterion removes 9 objects and leaves 44 targets. d . Have K$_{S}$ < 11 mag , driven by the sensitivity of our near-IR adaptive optics observations and to ensure a negligible extragalactic contamination (Padgett et al. 2008). This criterion removes 6 objects and leaves 38 targets. e. Are brighter than R = 18 mag according to the USNO-B1 catalog (Monet et al. 2003), driven by the sensitivity of our optical spectroscopy observations. This criterion removes 4 objects and leaves a final target list of 34 YSOc. The first two selection criteria ( [3.6]-[4.5] < 0.25 and [3.6]-[24] > 1.5 ) effectively become our working definition for a transition disk. These criteria are fairly inclusive and encompass most of the transition disk definitions discussed in § 1 as they select disks with a significant flux decrement relative to “full disks” in the near-IR or at all wavelengths. Many of our targets have IR excesses that only become evident at 24 µ m (see § 5.1.3). To check the reality of these excesses, we have visually inspected the cutouts of the 24 µ m Ophiuchus mosaic created by the Cores to Disks project 3 to confirm they show bona fide detections of our targets. We have also verified that all the 24 µ m images of our targets have been assigned an “Image Type” = 1 in the Cores to Disks catalogs, corresponding to objects that are well fitted by a point source profile. As a final check, we have verified that all our targets have “well behaved” SEDs that are consistent with reddened stellar photospheres shortward of 4.5 µ m and IR excesses from a disk at longer wavelengths. We have observed all 34 YSOc in our target list. However, as discussed in § 4.1.2, this list includes one likely classical Be star and 7 likely Asymptotic Giant Branch stars. The remaining 26 targets 3 available at http://irsa.ipac.caltech.edu/data/SPITZER/C2D/index cutouts.html