2009 Fermi Symposium, Washington, D.C., Nov. 2-5 3 detailed variability analysis for one of two reasons: (1) too few data points or (2) flux measurement un- certainties on the order of the amplitude of observed variability. It is important to note that, due to dis- crepancies between the sampling frequency in both bands, the variability indices for the 850 µ m band may be artificially depressed due to the fact that there are not always corresponding measurements at higher fre- quencies during flaring epochs. We follow the method of Kelly et al. [9], who model quasar optical light curves as a continuous time first- order autoregressive process (CAR(1)) in order to ex- tract characteristic time scales and the amplitude of flux variations. Although flaring behavior is not typi- cally thought of as an autoregressive process, we find that the light curves are well-fit by the models and therefore adopt the method here to study blazar sub- millimeter light curves. The CAR(1) process is described by a stochastic differential equation [9], associated with a power spectrum of the form In equations 3 and 4, τ is called the “relaxation time” of the process S ( t ) and is identified by the break in P$_{X}$ ( f ). The power spectrum appears flat for timescales longer than this and falls off as 1 /f 2 for timescales shorter than the characteristic timescale of the process. Taking the logarithm of the blazar light curve (in Jy) to be S ( t ), we adopt τ (in days) as the character- istic timescale of variability, after which the physical process “forgets” about what has happened at time lags of greater than τ . The two other relevant pa- rameters, σ and µ = b/a , are the overall amplitude of variability and the logarithm of mean value of the light curve, respectively. In the routine, we construct an autoregressive model for the light curves for a minimum of 100,000 iterations and calculate the value of τ from the break in the power spectrum in each instance. Due to the limited number of observations in the 850 µ m band, we performed this autoregressive analysis only for the 1mm light curves, which typically have more than 10 points per light curve. This method yielded some surprising results. In Figure 3, we see that the BL Lacs and FSRQs exhibit virtually no difference in characteristic timescale, with In general, we find that in the submillimeter, we are observing these blazars at or near the peak of the synchrotron component ( α$_{S}$ ∼ 0), but that Fermi - detected sources have more negative energy spectral indices overall than Fermi -nondetected sources. In Figure 4, we see that while the majority of Fermi blazars are observed on the rising part of the syn- chrotron component (at lower energies than the peak), all of the objects have very steeply falling γ -ray energy spectral indexes, putting the γ -ray peak at lower en- ergies than the observed Fermi band. Knowing that we are not observing the synchrotron and γ -ray com- ponents at analagous points in the spectrum may al- low us to better understand the magnetic field in the parsec-scale jet region and the population of external photons that is being upscattered to γ -rays. In Figure 5, the ratio between L$_{γ}$ and νL$_{ν,}$$_{1mm}$ re- flects the division between BL Lacs and FSRQs as well both classes extending across a large range in τ . Be- cause of the uncertainty for objects with shorter char- acteristic timescales, it is hard to draw any definitive conclusions about the differences between classes. It is important to note that τ does not necessarily rep- resent a flaring timescale, which is a behavior that typically operates on a scale of ∼ 10–100 days and not on the longer timescales we see in τ . Figure 3: Characteristic timescale (days) versus submillimeter luminosity (erg s − $^{1}$) in the 1mm band for all objects. Physically, τ represents a “relaxation timescale”, the timescale beyond which events are no longer correlated. 3.2. First-Order Continuous Autoregression dS ( t ) = 1 τ S ( t ) dt + σ √ dt ϵ ( t ) + b dt, (3) P$_{X}$ ( f ) = 2 σ $^{2}$τ2 1 + (2 πτ f ) $_{2}$. (4) 4. CONNECTION WITH GAMMA-RAYS eConf C091122