tokens: disk sources in the Perseus molecular cloud with the data collected in 2013, 2014, and 2015 (D. M. Segura-Cox et al. 2016, in preparation). Here we focus on seven of the candidate disks (Table 1 ; Figure 1 , left) which were observed with A-array prior to 2015 and can be well modeled with the prescription described in Section 4 . The observations were made in three-bit correlator mode, with a bandwidth of 8 GHz divided into 64 sub-bands. Each sub-band has 128 MHz bandwidth, 2 MHz channels, and full polarization products. The two 4 GHz basebands are centered at 36.9 GHz (∼8.1 mm) and 29.0 GHz (∼10.5 mm). Three sources were observed in each 3.5 hr block, and two sources were observed in each 2.75 hr block. Some observations were conducted as 1.5 hr blocks. 3C48 served as the flux calibrator, and 3C84 was the bandpass calibrator. The observations were taken in fast-switching mode to account for rapid atmospheric phase variations, with a 2.5 minute total cycle time to switch between the target source and the complex gain calibrator, J0336+3218. The total integration time on each source was ∼30 minutes for both A-array and B-array. We reduced the data with CASA 4.1.0 and the VLA pipeline (version 1.2.2). We executed additional flagging beyond pipeline flagging by inspecting the phase, gain and bandpass calibration solutions. VLA Ka-band data sets have an estimated amplitude calibration uncertainty of ∼10%, but only statistical uncertainties are considered in our analysis. Figure 1. VLA A+B array data (left), q = 0.25 model from u, v -plane best-fit (center), and residual (right). Images were produced with robust = 0.25 weighting. Contours start at 3 σ ( σ ∼15 μ Jy) with a factor of spacing. The synthesized beam is in the lower left. Table 1 Observations Note. Observation dates mark the start of the observations. Combined beam sizes reflect robust = 0.25 weighting. 3. ESTIMATED MASSES Two key quantities that describe disks are their masses and radii. While accurately determining disk radii requires modeling, masses are estimated from flux measurements (Table 2 ). By assuming optically thin emission, we estimate disk masses from the 8 mm dust continuum flux with the relation (Hildebrand 1983 ):where , d , , and , are respectively the total observed flux, distance, grain opacity, and blackbody intensity at dust temperature T d . We estimate at 8.1 mm by normalizing to Ossenkopf Henning ( 1994 ) at 1.3 mm using a dust to gas ratio of 1/100: = cm 2 g −1 . β = 1 is typically assumed for protostellar disks (Andrews et al. 2009 ), giving cm 2 g −1 . Mass estimates are inherently ambiguous within an order of magnitude due to uncertainties in the dust-to-gas ratio, T d , and β ; rather than compute a single mass estimate, we calculate lower and upper mass estimates for each source by varying T d . Lower masses were estimated by assuming T d = 40 K, and we determined upper estimates using T d = 20 K. These candidate disks range in flux from 867.5 to
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