The number of SNe in Figures 2, 3, 4, 5 and 6 ============================================= Figure 2. The left histogram contains 38 SNe and the right one contains 42. Please check. The bin sizes are slightly odd as well. ~0.65 days for the left histogram and ~2.2 days for the right one. Figures 3 and 5 contain 28 SNe. The ones not in the Hubble flow + SN 1995E + SN 1997cn are removed. What are the reasons for excluding SN 1997cn. Are they stated in the paper? Figures 4 and 6 has have 34 and 32 SNe, respectively. The parameters in these plots are idependent of distance. Why are there not 42 SNe in these plots.? Tables and Figures ================== The word "table" appears as Table. The word "figure" appears as figure and Fig. What is the A&A standard? Section 4. ========= 1st paragraph You might want to rephrase some parts of the first paragraph. "It consists of only three supernovae at z~0.5 ...different teams." -> "The data consist of near infrared (NIR) J-band observations of three supernovae (SN 1999Q, SN 1999ff and SN2000fr) at z~0.5, which have been observed with different facilities and by two different teams. "include the three supernovae in the Hubble diagram" -> "include two of these supernovae in the I-band Hubble diagram" The following is somewhat clumsy and is not necessary. "to show its potential and complimentarity with respect to the standard B-band Hubble diagram" -> "" Is the second paragraph necessary? Section 4.1 =========== 1st paragraph "I-band" -> "the I-band" "CFH-12k" -> "CFH12k" A space between the two brackets ")(" -> ") (" 2nd pararaph "two spectra" -> "spectra" "VLT" -> "the VLT" "z=0.543, see Lidman ... spectrum" -> "z=0.543. See Lidman ...spectrum" or z=0.543 (see Lidman ...spectrum)" "in restframe B, V and I filters" -> "in the restframe B-, V- and I-bands" "in (Knop et al. 2003)" -> "in Knop et al. (2003)" "stretch parameter" -> "B-band stretch of" "using" -> "with" "galaxy, (see also Section 6 ..." -> "galaxy (see Section 6 ..." 3rd paragraph If you want to have a reference for ISAAC, use Moorwood et al. 1999, ESO Messengere, 95, 1. "J Persson filters" -> Persson J filter" "Js filter" -> "ISAAC Js filter" Table 4. "Js" -> "Js-band" "on the ZP" -> "in the ZP" "restframe" -> "restframe days" "B-band maximum" -> "the date of the B-band maximum" "Restframe " -> "The restframe" Since the offset between IR and optical systems is given by the colour of Vega and since this is, in principle, part of the k-correction, perhaps it is not necessary to explicitly state the following in the caption. "and addition of the offset found between optical and IR systems" I recall that we had discussed this with Saul at some stage. It is mentioned in paragraph 7 and that is probably sufficient. Paragraph 5. "all of the" -> "all the" The sentence statring "We found systematic differences" sounds a bit harsh. I suggest "The difference between the two analyses are within the quoted uncertainties." The following sentence should be made clearer, since it is not clear which image is being scaled. Presumably, only the reference image is rescaled since the images with the SNe were taken during photometric nights. Instead of "The supernova images were aligned with the host galaxy images and the flux scaled to the one with the best seeing, using the field stars before performing PSF photometry." It may be better to write "Before peforming the PSF photometry, the images with the supernova and the reference image without it were aligned and the reference image was rescaled using bright stars in the field." Should we refer to Julian's program that does the PSF photometry? "on the estimate of the zero point" -> in the flux calibration" Figure 8. ======== "standard J Persson filter" -> "Persson J filter" (solid line) -> (solid green line) 7th paragraph "A term has been added" -> "The k-correction includes a term" Section 4.2 =========== 1st paragraph "CFH-12k" -> CFH12k" "in I-band" -> "in the I-band" 2nd paragraph "available at Keck" -> "that was used in these observations" "ISAAC-Js," -> "ISAAC Js filter, which is" "published observed photometry" -> "published photometry" " Table 5. ======= "restframe" -> "restframe days" "B-band maximum" -> "the date of the B-band maximum" See the comments made about the caption to table 4. Section 4.3 =========== 1st paragraph "magnitudes(Schlegel)" -> "magnitudes (Schlegel)" 2nd paragraph 'Keck" -> "the Keck" I suggest the following wording for the 3rd paragraph. "A fit to the published restframe I-band data of SN 1999Q shows that it is a 4 (to check?) sigma outlier in the I-band Hubble diagram. We re-analysed the publicly available SofI data and found that SN 1999Q has $J=22.63 \pm 0.15$, which is significantly brighter than the published value - $J=23.00 \pm 0.14$ (Riess et al. 2000). Due to this discrepancy, we decided to not include this SNe in the rest of the analysis." Figures 9 and 10. ================ "Best ..." -> "Out of 42 I-band templates, the best" delete "the nearby" Section 4.4 =========== Paragraph 3. "are few" -> "are only a few" "light curve template" -> "the lightcurve template" "giving a" -> "satisfying" "SN 2000fr this ...estimate" -> "SN 2000fr, it is compatible with the statistical uncertainty. Why is it conservative estimate of the systematic uncertainty? Table 6 ======= "Columns are: redshift, number" -> "Columns are: IAU name, redshift," Section 4.5 =========== "run in order to test the fitting" -> "run to test the robustness of the fitting" "systemmatic uncertainty in" -> "the robustness of" "all the three SNe" -> "both SNe" "on I_max" -> in I_max" "in the distribution" -> "in the distribution of I_max" Section 5. ========== Paragraph 1 "all SNe" -> both SN 2000fr and SN1999ff" "in their" -> "from their" Paragraph 2 "without and with" -> "with and without the" "case a and case c" -> "case c and case a" "in presence" -> "in the presence" "large grain dust" -> "large dust grains" I think we need to modify the last sentence in this paragraph so that it better matches what is said in the abstract. I suggest. "Although the number of high redshift SNe is still too low to draw strong conclusions, the model in which SNe are dimmed by intergalactic grey dust is disfavoured." Then, I suggest that the 3rd paragraph, which is only one sentence, is modified and added to the beginning of the 4th paragraph. "Clearly, systematic uncertainties in the method used here cannot be explored with only two supernova." Figure 11. ========= "three" -> "two" Table 7. ======= "Reduced chi-sq. of the high redshift data to each model ..." -> The reduced chi-sq. of each model ..." "2 dof" -> "1 dof" There is something whic is odd in this table. Why does the chi-sq get smaller for some models when systematic uncertainties are removed? I would have thought that the chi-sq. would be reduced if you increased the error? Section 6. ========= Title. I suggest the following change. "SN colours and study of intergalacitic" -> "SNe~Ia colours and grey dust" Paragraph 1 "for extinction tests for non-standard" -> "one to search for" "only weak" -> "only a weak" "large grain dust" -> "large dust grains or "grey dust"" The next sentence is rather long. It could be reworded to "If we assume that grey dust is responsible for the dimming of SNe~Ia in the B-band at z~0.5, we can calculate the expected extinction in other filters and compute the resulting colours. Following Goobar et al. (2002a), we use the SNOC Monte-Carlo package (Goobar et al. 2002b) for two cases of the total to selective extinction ratio - R_V = 4.5 and 9.5. We assume that the dust is evenly distributed between us and the SNe in question and we assume a flat cosmological model with a zero cosmological constant." Paragraph 2 The first and second sentences can be combined into one. "The measured B-I and B-V colours of SN 1999ff and SN 2000fr, corected only for Milky-Way extinction, are presented in tables 8 and 9 and plotted in figure 12." then, you can add a modified version of the last sentence in this paragraph next "The error bars include the intrinsic dispersion in the colour" and end with. "The expected evolution in the B-I and B-V colours of an average SNe~Ia in the concordance model and in the two models with grey dust and without a cosmological constant are also shown" As I as writing these lines, a thought came to me. In principle, the models with grey dust should be redshift dependent. I.e, we should see a greater colour difference for SN 2000fr than for SN 1999ff, since the light from SN 2000fr would travel through more dust. Paragraph 3. I suggest the following for the first sentence be converted into two sentences. "We use the chi-sq statistic to quantify how well the data agree with the models. It is computed for both B-I and B-V and it is computed for SN 2000fr and SN 1999ff separately and together." "the models being compared" -> "the models" "thier combination" -> "the combined results" Paragraph 4. "robust" -> "effective," (Note the comma as well.) "The residuals ... calculation" -> "The residuals between the data and the models are averaged with a weight that is determined from the covariance matrix." Remove the comma after E(X-Y). "X-Y average colour of local supernovae, ..." -> "average X-Y colour of nearby SNe~Ia, ..." Paragraph 5. "local sample distribution" -> "distribution of colour excesses of nearby SNe~Ia" "the left panels" -> "the left-hand panels" ",where the spectroscopically peculiar ... analysis. can be a sentence. I.e., "Spectroscopically peculiar ... anlysis." Where do these 27 SNe come from? You might want to add a reference to your own paper here. "of one colour distribution" -> "in that colour" "represent 68.3 ... probability" -> "incorporate 68.3 ... of the sample" Paragraph 6 "right panels" -> "right-hand panels" "combined values of colour excess for" -> "colour excesses of" "These are ... dust". -> "For comparison, the colour excess distribution of nearby SNe~Ia in the absence of grey dust is shown as the solid lines" "displaced" -> "that is displaced" This dotted ellipse should be redshift dependent. It should be further away for SN 2000fr than for SN 1999ff. It is not clear to which pronoun the word "latter" referes to. The last 3 sentences could be re-written to "For clarity, only the ellipse for the R_V=9.5 dust model is plotted. The R_V=4.5 model would be displaced by a further (0.03, 0.04)." Paragraph 7 It would better to split the first sentence into two. "We compared the low and high redshift colour distributions by computing the (reduced?) chi-sq. of the high redshift data for all three models. We cover two cases: in the first case, the nearby SNe~Ia are corrected for extinction by dust in the host galaxy, and, in the second case, they are not." As a possibility for future work, I wonder if there is another test we can do, since what we are trying to do is to compare two distributions - the low redshift one and the high redshift one. The third sentence would also be easier to read if it were two sentences. "In the first case, the reduced ... respectively." "model" -> "models" "In the second case, the reduced chisq. are ... (no need to repeat the models here) ... respectively." "of the nearby" -> "in the colours of the nearby" "on the high redshift" -> "in the colours of the high redshift" "for computing" -> "in computing" Paragraph 8 "presence" -> "the presence" "the SN local sample" -> nearby SNe~Ia. "the systematic effects" -> "systematic errors" "to be able to exclude" -> "to exclude" "give" -> "is" Does the last paragraph repeat what is said in the last sentence of paragraph 7. Perhpas the two can be merged. Table 8 ======= "the three high redshift SNe" -> "for SN 2000fr and SN 1999ff" "Epoch" -> "The Epoch" "days" -> "restframe days" "B-band" -> "the B-band" Table 9 ======= See the comments to table 8 and "data not in the analysis because out" -> "The data are not in the analysis because they are out" "studies" -> "studied" Figure 12 ========= "High redshift SNe colour evolution ..." -> The evolution in the colour of SN1999ff (squares) and SN 2000fr (diamonds) ... "compared to a ... and to ..." -> "compared to the colour evolution of an average SNe~Ia in a ... and in ..." Figure 13 ========= "Left panels" -> "Left" or "Left-hand panels" "distribution of combined colour measurements for the local sample of supernovae" -> "distribution of nearby SNe~Ia" "The solid contour is ..." -> "The solid contours incorporate 68.3 ... of the sample." "Right panels" -> "Right" or "Right-hand panels" "combined colours of the high redshift supernovae ..." -> "location of SN 1999ff and SN 2000fr in the E(B-V) vs E(B-I) plane compared to the distribution defined by nearby SNe in the case of no IG dust (solid ellipses) and in the case of IG dust with R_V=9.5 (dashed ellipse)." Section 7 ========= 1st paragraph "supernova progenitors" -> "progenitors of SNe~Ia" "been often" -> "often been" - Actually, I am not sure which one is correct. I'll have to check my English grammer book. "to the observed" -> "for the observed" "older galaxies show different composition distribution than younger ones ... metallicity, therefore offering different environmental conditions to the exploding star." -> "more distant galaxies should have lower average metallicities than nearer ones," "finding always" -> "always finding" 2nd paragraph "our attempt does not give evidence for evolution of the average SN colours" -> "our results do not show any evidence for evolution in the colours of SNe~Ia." "I-band light curve for" -> "I-band light curves of " "by templates" -> "with templates" I think that we might have to provide a stronger case than we currently have done if we are going to say the following. "The restframe I-band light curves of the high redshift SNe were all fitted with templates showing a second prominant peak, i.e. inconsistent with the intrinsically underluminous supernovae necessary to explain the apparent faintness of high redshift SNe in a flat universe with a zero cosmological constant." I agree that both SN 2000fr and SN 1999ff can be better fit with I-band light curves that show a prominant second maximum and that SN 1991bg and SN 1997cn like light curves do not fit these high redshift supernovae. But, are such SNe necessary to explain the ~0.4 magnitude difference between the concordance model and the flat lambda free model? "is evident" -> "is unambiguously evident" Some might argue that it is evident for 99Q, so I added the adjective unambiguous. Section 8. ========= 1st paragraph "feasibility" -> "feasibility and utility" 2nd paragraph "fitted light curve" -> "fitted light curves" "for the I-band ... s_I" -> "between the peak I-band magnitude and both the B- and the I- band stretches (s_B and s_I)." 4th paragraph "a template set built on the local SNe sample" -> " templates that were built from nearby SNe~Ia" "high redshift light curve" -> "high redshift lightn curves." "the low statistics of the sample does not yet give statistically meaningful conclusions" -> "the high redshift sample consists of only two SNe~Ia." As an added comment. If you trust the statistical errors, and we have no reason not to trust them, then two SNe are statistically meaningful. Why shouldn't they be meaningful? The point here is that the sample size is small, not that the statistical conclusions are not trustworthy. 5th paragraph "of the observed" -> "for the observed" "evolution effects in the supernova properties" -> "SNe~Ia evolution" "multi colour" -> "multi-colour" The 3rd and 4th sentences could be joined together. "Although no firm limits on the presence of grey dust could be set, a MC simulation indicates that a sample of at least 20 well observed SNe~Ia would be enough for setting limits through the multi-colour technique used in this paper." "A similar technique, but using QSO colours ..." -> "A similar technique, using QSOs instead of SNe~Ia," Remove the comma after (2003). "dust being" -> "dust as being" 6th paragraph Could you please explain "selection effects for bright objects during the search campaign" "Thus, the use of I-band measurements of ... tools" -> "Restframe I-band observations of distant SNe are feasible, useful and complimentary to the well established observations in the B-band." Perhpas this last sentence can be placed as a paragraph.