Long-Time Trends in Night Sky Brightness and Ageing of SQM Radiometers
, Renata Binotto 2, Stefano Cavazzani 3,4,5, Andrea Bertolo 2, Sergio Ortolani 4,5 and Ivo Saviane 6
Round 1
Reviewer 1 Report
Decision in the attached file
Comments for author File: 
Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
In the article " Long-time trends in Night Sky Brightness and ageing of SQM radiometers", the authors observed Night sky brightness with SQM radiometers for long-term measurements. The instrument used is a standard SQM. The main findings are the Night Sky Brightness comparison of both cities. The findings can be interesting for the wider community, currently, the analysis of the skyglow is quite a popular topic. The writing of the manuscript looks good overall. I see the novelty in both scientific findings and methodological approaches. The authors clearly state the scientific significance of Night-time light changes in the study area. The manuscript shows a clear picture of the scientific foundation, structure, focus and clarity of argumentation. The objectives are very clearly outlined in the introduction, the used datasets are well described with sufficient detail.
However, I have a few concerns/suggestions, particularly centring on the method section for improvement.
SQM is a commonly used instrument, but requires regular calibration due to its long-term instability. Observed long-term changes in SQM sensibility are smaller than changes observed in Italy and Chile, so the measured values are valid. However, I recommend adding information about the long-term stability of the SQM and corresponding reference(s).
The paper is well-written and uses actual data for light pollution. Although the paper is of interest, there are several comments on the paper as follows;
Since there is no multi-dimensional analysis of the necessity and differentiated insight, The research paper looks like a measurement report.
It would be great for the reader's community to add the study area map as well.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
This study evaluated the Sky Quality Meter (SQM) radiometer in terms of stability at two sites: one in Italy and the other in Chile, using the twilight method considering both sunset and dawn measurements. The authors found a darker trend and suggested a correction.
The paper is well written overall. One question was about how longterm cloud and aerosol changes may have affected the measurements. It's not clear how this is handled in this study. Also, minor corrections are needed.
Line 141: "A part a brief...". Not sure what the authors are trying to say. Please check and revise.
Line 144: "according it". Probably should be "according to the model"?
Author Response
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Author Response File: Author Response.pdf
