The referee turned this around insanely fast, so maybe we can get this accepted before anyone reads the proposal. :)
I think most of these issues can be dealt with quickly. The most substantive is his “what is the point of this paper, actually?” I am thinking we should change the title to “Limits on Polarized Leakage for PAPER Epoch of Reionization Measurements at 126 and 164 MHz” and basically formulate the paper as the referee’s option (2). Actually getting limits on the polarized spectrum directly (option 1) requires undoing the presumed ionosphere attenuation, and that is somewhat uncertain. (3) is the work which would need to be done to get (1), and we are doing this now with more realistic ionosphere and model of the beam leakage, but I don’t want to hold this paper up. (4) would also be subsumed in what we are doing now as well. Any comments? James Aguirre Associate Professor Department of Physics and Astronomy University of Pennsylvania 209 South 33rd Street Philadelphia, PA 19104 (215) 898-9596 (office) (215) 898-9646 (lab) [email protected]<mailto:[email protected]>.edu http://www.sas.upenn.edu/~jaguirre/ Begin forwarded message: From: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Subject: Referee's Report on ApJ/ApJ98178R1 Date: February 15, 2016 at 9:24:31 PM EST To: "Aguirre, James" <[email protected]<mailto:[email protected]>> Cc: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Reply-To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>>, "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> February 15, 2016 Prof. James E. Aguirre University of Pennsylvania Department of Physics and Astronomy 209 South 33rd Street Philadelphia, PA 19104-6396, USA Philadelphia, PA 19104-6396 Title: New Limits on Polarized Power Spectra at 126 and 164 MHz: Relevance to Epoch of Reionization Measurements, ApJ98178R1 Dear Prof. Aguirre, The revised version of your paper cited above was sent back to the referee, who appreciates the changes you have made, but has some questions about the new version. When you resubmit the manuscript, please include a detailed cover letter containing the (mandatory) listing of the changes you've made to the text and your responses to the report. Click the link below to upload your revised manuscript; https://apj.msubmit.net/cgi-bin/main.plex?el=A2Ew2Ye5A6HqI5J5A9ftdFW5002wHRT2Rs3yyIm8XfwZ Alternatively, you may also log into your account at the EJ Press web site, http://apj.msubmit.net<http://apj.msubmit.net/>. Please use your user's login name: jaaguirre. You can then ask for a new password via the Unknown/Forgotten Password link if you have forgotten your password. Reviewers find it helpful if the changes in the text of the manuscript are easily distinguishable from the rest of the text. Therefore we ask you to print changes in bold face. The highlighting can be removed easily after the review. The Astrophysical Journal has adopted a new policy that manuscript files become inactive, and are considered to have been withdrawn, six months after the most recent referee's report goes to the authors, provided a revised version has not been received by that time. If you have any questions, feel free to contact me. Regards, Ethan T. Vishniac AAS Editor-in-Chief Johns Hopkins University ---------------------------------------------------------------------- Referee Report Reviewer's Comments: The authors, for the most part, have addressed many of the comments I had on the first draft. In particular, they have done an excellent job with regards to addressing my concerns about ionospheric effects. This does now, however, invite the question of what the paper is actually aiming to measure (which I expand on in my first comment on the revised paper below). Comments on author reply: 12) My apologies, this was due to left-over text from an earlier draft of comments I had prepared - please ignore. 15) My comment here was more to assess whether structure in P_Q or P_U may explain structure in P_V as a result of leakage (one would not normally expect "structure" in P_V). 16) The axis units now appear fine. Comments on revised paper: p.1, title: The paper needs to be clear of what the aim is. Is it to (1). Place limits on the polarised power spectra at 126 and 164 MHz, (2). Place limits on the instrumental leakage measured for PAPER, (3). Place limits on the effect of the ionosphere on polarised power spectra, and/or (4). Place limits on the effect of ionosphere-affected polarised power spectra leaking in to the EoR power spectrum. The title of the paper suggests (1) but there is no mention of what the new limit is in the abstract and the conclusion only suggests that they are "sufficiently low" but doesn't mention what they are. Based on the addition of the new text in sections 3.7, it seems more like (3) or (4) are the main goals now. Having said that, undoing the effect of the attenuation caused by (3) could be done to place a limit on (1). p.1, abstract: "of of"->"of" p.1, abstract: So what is the new limit on polarised power spectra at 126 and 164 MHz? Depending on which of (1), (2), (3) and/or (4) is your goal you should state what the limit is. p.1, section 1: "Polarized emission ... is a potentially problematic foregrounds"->"Polarized emission ... is a potentially problematic foreground" p.1, section 1: "with modest calibration requirements in future experiments like SKA (Sutinjo et al. 2015)" - the referenced paper refers to reducing the effect of instrumental leakage through improved beam modelling with the MWA. It does not suggest modest calibration requirements for SKA-like instruments. Furthermore, SKA is an instrument and not an experiment. p.1, section 1: "diffuse emission in the southern hemisphere at frequencies below 1.4 GHz are due to Mathewson & Milne (1964, 1965)" - Presumably Mathewson & Milne had little to do with causing diffuse emission below 1.4 GHz. p.2, section 1: "Regarding point sources, the number of bright sources below 200 MHz reported in the literature is small" - While this is certainly true, it should also be pointed out that only a small part of the southern sky (and northern sky) has been surveyed for such sources. p.2, section 1: "goal of this paper is to directly quantify the effect of polarized leakage on upper limits on the EoR power spectrum" - this goal (which is more like (4) mentioned above) is different to that of the title (which is more like (1) mentioned above). p.7, section 4.1: "clearly due to the one observed feature in Figure 6" - be more specific about where this feature is, do you mean the feature in P_P at |k|<0.2 between 1h and 4.5h? p.7, section 4.1: "also evident that Band I is less consistent with zero than Band II" - Band I is not shown in Figure 6, or anywhere for that matter! p.7, section 4.1: "leakage terms which which"->"leakage terms which" p.7, section 4.1: "0.35hMpc"->"0.35 Mpc"; also "0.345 hMpc"->"0.35 hMpc" to be consistent. p.7, section 4.1, last paragraph: Given the low level of leakage assumed and the attenuating effect of the ionosphere, the feature between RA 6h and 8h is particularly concerning. Given that the source appears to be unphysically bright in polarised flux, have there been attempts to jackknife or partition the data (e.g. by taking only some days) to test whether the source is still present? Could this be due to a satellite in the field of view at that LST? If the feature is due to instrument systematics shouldn't it be consistent at all LSTs? p.8, Figure 6: It is difficult to assess whether the power shown in the power spectra is saturated with the given intensity scale. For example, could the structure in P_V reflect the brightest features in P_P? At what point does P_P peak and where does P_V peak? p.8, section 4.2: How does the predicted leakage compare with what is actually seen with PAPER? For example, the images shown in Figure 2 of Kohn et al. (2016) show clear evidence of leakage in Stokes Q, U and V (although it is difficult to read off the paper itself to give an actual percentage because of the intensity scales used - perhaps as part of the collaboration you have access to the actual images?). p.9, section 5: The limits summarised in the conclusion do not address the limits suggested by the title of the paper. So what are the new limits on the polarised power spectra at 126 and 164 MHz?
