Hi all, We've had some email threads going about prelim results seen in Stefan and Sarah's latest pager and I wanted to share a few of my thoughts with the whole group. Click on http://bmode.caltech.edu/~spuder/analysis_logbook/analysis/20130823_sim1450… I find it very encouraging that the anomalously large high ell TB and BB appears to be relieved by "all four" deproj (specifically diff ellipt.) We should be able to confirm that the shifts in these spectra are consistent with measured diff ellipticity--the mode that makes the difference. Obviously this is also (another) caution to us regarding our systematic error budget for these spectra at high ell, and the need to carefully quantify the effects of the undeprojected residuals. EB in B2 remains unresolved--it still looks highly significant, and its negative amplitude roughly traces the EE spectrum. Keck doesn't see it. Perhaps there is some error in B2's chi calibration that explains this. Looking at the form of B2's EB (highly significant) and TB (still non-zero, but less significant now), and comparing to the EE and TE and the expected leakage resulting from an overall pol rotation angle Delta-alpha: TB = TE sin(2 Delta-alpha) EB = 1/2 EE sin(4 Delta-alpha) (see e.g. arXiv:0811.0618 eq 3-7), it appears to me that a rotation of Delta-alpha = -1 deg would give a good fit to both the EB and TB spectra. Jon Kaufman (or anyone else), are you planning to do this? But by far the most serious issue for publication of an r limit remains the tension between B2 and Keck in the BB spectra at ell 50-150. (Click on lmax=200). Clem correctly emphasized this yesterday, I think. He also characterized the B2 BB spectra as being equivalent to r=0.3 to 0.5 yesterday. Looking at this plot myself, accounting for the known lensing signal, I think the excess BB at ell=70 looks more like r=0.2 to 0.25. Accounting also for foregrounds (Jamie T's latest post makes dust in that bin at r~0.05 seem not unlikely) the "unexplained" excess would be less. Other plots may make this more clear. For now I think we should be careful not to overstate the amplitude of the issue here, but it is the significance of the tension between B2 and Keck that we should continue to focus on. I think Clem's posts from late May / early June are the right path here. I know he is planning to repeat them using the new sims, and I think a lot hinges on the detailed results. For the main science goal of a limit on r, it seems necessary to me to quantify the ell = 30-150 BB tension between B2 and Keck before we can consider greenlighting a set of results for release. In the meantime, we will continue to push hard on quantifying the T->P leakage from the beam sims and uncertainties in those estimates at all ell, the impact of crosstalk, and other threads we discussed. Looking at the pager (lmax=500) it also seems likely we have a detection of BB lensing. Chao-Lin has previously raised the possibility of pushing a result out on that. I am somewhat skeptical this is any easier than an r limit until we've worked through the systematic error budget (we have not been focusing on high ell with jacks, etc) but I do think this goal is a good one and motivates including the higher ell in our effort to wrap up systematics. John -- ___________________________________________________________________ John Kovac jmkovac(a)cfa.harvard.edu Associate Professor, Harvard University Astronomy Department 160 Concord Ave rm 310, Cambridge MA 02138, 617-496-0611