SDGSAT-1 TIS Prelaunch Radiometric Calibration and Performance

Round 1

Reviewer 1 Report

SDGSAT-1 TIS Prelaunch Radiometric Calibration and Performance -Peer Review

 

This manuscript presents a nice summary of some SDGSAT-1 TIS performance parameters. I think that the major problem with the paper is a quite low level of English language and style. Despite that, I believe I was able to understand most of the content and it appears to me as technically correct. However, the paper definitively needs clearer explanations of methods (in clear English), ensure that all acronyms are spelled out, all figures are referred to and good English edits.

 

Several additional comments and suggestions for improvements are listed below:

 

Line 20 - What does ‘FPA’ stand for? “Focal Plane Assembly”?

Line 39 – Would you please explain how the image quality is improved by adding an additional band?

Line 64 – How does the sensor see deep space? Is there a separate port (it is not shown in Figure 1)?

Lines 66-67 - Please explain how variation in the instrument’s self-emission can be removed by viewing deep space.

Line 167 - Figure 5 is nice but not described and referred to anyway in the manuscript

Table 1 - “Width” should be something like “Ground track width”

Line 175 – “figure” should be “Figure 6”

Lines 185-186 – It is not clear to me what led you to conclusion that the effect of background variation due to the variation of instrument temperature can be ignored. Please explain.

Line 209 – I think there should be “As shown in Figure 8, …”

Line 214 – What are k1 and k2? How are they calculated?

Lines 229-233 – Needs clearer explanations of terms. “n” should probably be “N”. The “mean DN” should be written properly. What is “the target” in definition of “L”? “table” should be “Table 2”. What is meant with “frames”? Does “frame” refer to a single pixel or to an average of all modules? Does TDI method play a role in NEdT calculations?

Line 274 – “we slightly change the ambient temperature…” How were you changing the ambient temperature? That is important for understanding Fig. 12. Btw, comparing changes in optics, scan mirror and Dewar temperatures during 12-hour period shown in Figure 12 to changes in background response, the background response looks quite insensitive to the ambient temperature changes (at the scale presented in the figure)

Line 276 – ‘Fig” should be “Fig 12”

Lines 280-282 – The Figure title seems to be incorrect. The plots show variations vs. time, not temperature.

Line 283 – “figure 9” should be “figure 12”.

Line 284 – Where did the statement “the maximum temperature change of the telescope is 2.71K” come from? Looking at Fig. 12, the max variation is about 1.1K.

Lines 285-286 – How are the DN fluctuations calculated?

Line 298 – “the TIS has a good performance that meets the requirements” What are the requirements?

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

This research article lacks a few required sections and is not ready to be published in a research journal.  There is no "past works" section and there is no "future works" section.  I recommend reviewing the past works and including a detailed section of how calibration is done currently and the methods used by other authors.  

After this is completed, I recommend generating a set of tables that compare your calibration method to past methods covered in the "past works" section.  That way, the reader will see if your method is better or worse than current methods.  At present, you have only presented your own results.  A comparison of your results to other common methods is required.

I recommend added a future works section.

There are numerous minor errors in the paper.  A few are listed below but the paper should be reviewed to make sure all errors are removed.

Line 14, a space is required after "TIS" before you start the "(Thermal....)"

Line 20, spell out first use of Focal Plane Array (FPA).

Line 29, space after "imager".

Line 51, spell out TDI first use.

Line 80, put Title with graph.

Before line 81, add space between table and paragraph.  Typical throughout document.

Figure 6, Integration is mis-spelled.

Line 177, Formula is mis-spelled.

 

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

The instruments which could enable the air, water and soil pollution assessment are very useful. The technical note is well written and has high scientific soundness. I have some issues and recommendations for the authors.

1) All the abbreviations should be clarified (also the well known like FPA, DN e.t.c.).

2) Line 104: may be "... for every two modules" ?

3) Line 144: may be "...may come"?

4) What happens if the temperature of FPA varies in the range of 60-80K?

5) Describe, please, the graphs on Figure 4 with more details.

6) Explain, please, why the red graph on Fig.7 has two peeks. How can this fact influence the resolution  of the instrument presented in the paper?

7) I can not see the dashed Lines on Fig.8.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

I think the revised version of the manuscript has overall improved a lot, but still could use some minor corrections of English language and style.

 

Several additional comments are listed below:

 

Lines 41-43 – “What’ more, the 41 adding band 8.0 - 10.5μm has lower NEdT than 10.3-11.3,11.5-12.5μm band, which improves its sensitivity.” “its” in this sentence seems to be related to “band 8.0 - 10.5μm”, but it probably refers to “land surface temperature” discussed in previous sentence.

Line 80 – I could not find reference to this table (Table 2) anywhere in the text

Line 90 – “Each module has 512×4 pixels…” Could you please explain this? Based on Figure 2, there are 512 pixels per each band on each module. And there are only 3 bands (suggesting there should be 512x3 pixels). Or perhaps “512x4” refers to pixels per each band on each module (which would mean that 4 pixels are used for TDI). Please explain.

Line 134 – It appears to me that the target used for this prelaunch test was a low-temperature target, but that is not stated in this section. Please explain.

Line 147 – “ADC” should be spelled out

Lines 239-240 – “by adjusting the attitude of satellite at a low frequency.” I think you should be more specific about the frequency and state something like “every two weeks” (as suggested from Figure 11).

Line 258 – There is no reference to this figure (Figure 11) in the text

Author Response

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Reviewer 2 Report

My comments on adding a section of past works by other researchers was not addressed.  No such section was included in the new document.

My comment on adding comparisons to other past methods was not addressed.  No such graphs or data was presented.

This paper does not show what has been done in the past and it does not show how this method compares with other methods.  Therefore, it is an application paper and cannot be published as a research article. 

Since it is a Technical Note, it is good to publish. The authors could consider my suggestions in future work. 

Author Response

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Author Response File: Author Response.docx