Characterisation of the Atmosphere in Very High Energy Gamma-Astronomy for Imaging Atmospheric Cherenkov Telescopes

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

I have reviewed the manuscript "Characterisation of the Atmosphere in VHE gamma-astronomy

for Imaging Atmospheric Cherenkov Telescopes" by D. Prester, et al. This paper describes the measurement, characterization, and quantification of atmospheric conditions that are important for understanding and analyzing results from Imaging Atmospheric Cherenkov Telescopes (IACTs) such as the MAGIC and CTAO instruments, that observe very high energy gamma rays from astrological sources. Overall this paper is very well written and clear. The reanalysis of MAGIC LIDAR data in section 3.1 to parameterize the shape and extension of clouds is quite nice and no doubt useful for the experiment. The analysis of vertical aerosol optical depth for MAGIC is also interesting. This will be of broad interest to scientists working in the area of VHE gamma ray astronomy.  After a few comments/questions, enumerated below, are addressed, this paper will be very suitable for publication in Universe.

 

1. Fig. 1 contains interesting information that illustrates the MAGIC data, but it is not appropriate for a journal publication in its present form. It is apparently a printout from the telescope's analysis software. Some of the information such as source/wobble (red) and run number are not useful here and too hard to read. The legend is crowded and not informative for a journal figure. I recommend the authors reformat this plot, delete the extraneous fine print, and improve the legend.

 

2. Similarly, Fig. 2 is potentially interesting but difficult to interpret. It requires a legend and a more detailed, informative caption.

 

3. Line 329, in reference to Fig. 5 "Clearly, the criteria have been set too loosely" begs the question Why? Was an error made, or are there trade offs to consider in the zeropoint filter? Why not redo the analysis/plot using the best criteria?

 

4. Fig. 5: The general trend in the zeropoints is an increase vs. time due to degradation of the lens. But six dips can be seen and only one of these (Sept. 2021) is clearly explained as due to a lens replacement.The other dips are hard to understand. Was the lens cleaned? What is the explanation?

Author Response

Dear Reviewer,

Many thanks for your work on improving the quality of our paper, and the useful comments. We have updated the paper according to your suggestions. Please find below the answers.

Best regards,

Dijana Dominis Prester

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1. Fig. 1 contains interesting information that illustrates the MAGIC data, but it is not appropriate for a journal publication in its present form. It is apparently a printout from the telescope's analysis software. Some of the information such as source/wobble (red) and run number are not useful here and too hard to read. The legend is crowded and not informative for a journal figure. I recommend the authors reformat this plot, delete the extraneous fine print, and improve the legend.

 

Thank you, we agree with this suggestion. Accordingly, Fig. 2 has been modified.

The source names and wobble numbers are removed (called the 'fine print' by the reviewer). The legends are cleaned up, some entries which were not helpful removed, reworded some entries, and made text larger. The plot now has larger fonts, extra padding from the root macro is removed. Now all the text in Fig. 1 is approximately the size of the article's main body text. References to the source names and wobbles are removed from the Caption. 

In the Caption, following changes were made: (DC) -> (DC; green and red) and (TH) -> (TH; blue). 

 

2. Similarly, Fig. 2 is potentially interesting but difficult to interpret. It requires a legend and a more detailed, informative caption.

 

Thank you, we agree with this suggestion. Accordingly, Fig. 2 has been updated with additional legends and descriptions to make it better understandable. A detailed caption has been added that describes every element of the figure. 

 

3. Line 329, in reference to Fig. 5 "Clearly, the criteria have been set too loosely" begs the question Why? Was an error made, or are there trade offs to consider in the zeropoint filter? Why not redo the analysis/plot using the best criteria?

 

4. Fig. 5: The general trend in the zeropoints is an increase vs. time due to degradation of the lens. But six dips can be seen and only one of these (Sept. 2021) is clearly explained as due to a lens replacement.The other dips are hard to understand. Was the lens cleaned? What is the explanation?

 

Thank you for your both remarks and suggestions 3. and 4., we agree it was not clearly written. We have rewritten the paragraphs explaining Fig. 5 (lines 337-360 in the new version of the paper).

 

Reviewer 2 Report

Comments and Suggestions for Authors

Ground based observations of VHE gamma rays from astrophysical sources are significantly influenced by atmospheric conditins.Authors from aerosol optical maps obtain the characterisation of the clouds needed for data correction and optical observation sceduling. This methodological paper contain many technical details dedicated for limiting number of readers. Nevertheles the discused subject is interesting and worth publication.

1. Please check the description of the horizontal axis in Fig.3 (left panel)

2. Some definition (more broad desription) of extinction coefficient, Vertical Aerosol Optical Depth will be valuable for broad spectrum of readers.

The paper is valuable, well written, and I think that this manuscript can be published (optionaly with small revision).

 

Author Response

Dear Reviewer,

Many thanks for your work on improving the quality of our paper, and the useful comments. We have updated the paper according to your suggestions. Please find below the answers.

Best regards,

Dijana Dominis Prester

-------------------------

 

1. Please check the description of the horizontal axis in Fig.3 (left panel)

 

Thanks a lot for pointing this out. Fig. 3 has been updated with a corrected horizontal axis description.

 

2. Some definition (more broad desription) of extinction coefficient, Vertical Aerosol Optical Depth will be valuable for broad spectrum of readers.

 

Thank you, we agree with this suggestion. A new paragraph has been added in the Introduction section (lines 70-81).