The attached supplementary pdf file contains the comments.

The manuscript by Duren et al. describes the Carbon Mapper satellite-based system for the detection and quantification of greenhouse gas emission point sources. This is an exciting development in the quickly evolving field of methane and CO2 remote sensing, to which Carbon Mapper will soon become a key contributor. This is confirmed by the mission performance results reported in this document (the plume maps in Figs. 14, 15 or 18 are particularly impressive). The manuscript is a perfect fit for AMT and I recommend its publication in general.

On the other hand, the overall presentation of the manuscript suffers from poor formatting, lack of clarity, and minimal attention to structure and detail in my opinion. The manuscript gives the impression that the authors were not fully invested in preparing a submission of suitable quality for peer-reviewed publication, and I don’t think that the manuscript has been proof-read before submission. From my point of view, significant revision is required to bring the manuscript to a level where its scientific contributions can be properly assessed and appreciated.

Here is a list of the parts of the manuscript where I think improvements are needed:

- Abstract: it is very long, and reads more as an executive summary of an internal mission report than as an abstract of a scientific pubilication. I would propose to shorten it substantially, especially in the parts not directly related to findings of this study.

- Sec. 1.1: these paragraphs provide a review of past and current missions with sensitivity to methane and CO2. However, the part of this section referring to “point source images” is strongly biased towards the instruments and work by the authors. It is striking (and a bit annoying) not to find a single reference to the GHGSat program, which is very similar to Carbon Mapper in terms of observational requirements and capabilities (with a superior performance for GHGSat currently because of their higher number of operating satellites). It is also surprising not to find references to the retrieval and analysis work that has been done (mostly by groups in Europe and China) with other space-based imaging spectrometers, including EnMAP, PRISMA and the AHSI onboard the GF and ZY1 satellites, which are also very similar to the Tanager instruments. I would strongly request the authors to better reflect the international context in their study.

- Sec. 2: it is also very lengthy: In my opinion, the first two paragraphs read as a new introduction section, sec 2.1.2 does not add meaningful content, L388-397 are redundant with previous contents, and L399-419, L470-480 and L620-655 provide much more detail on the instrument design than what is actually needed to understand Tanager’s potential for GHG retrievals. I believe that the whole section would benefit from shortening and focusing on the mission and instrument parameters directly affect

- Sec. 2.5.3: please explain how uncertainties in emission rates are estimated

- Sec. 4.1, MDL: does this MDL analysis only refer to one pixel standing out from the background XCH4 values, as I seem to interpret from Eq. 7? I don’t think that you would claim a plume detection if this is only based on a 1-pixel enhancement, but you would need several connected pixels with an enhancement n-times higher than the noise level. Is this correct? If so, I don’t this metric can be used as an absolute measure of detection limit, as I think you are doing within this section.

Other minor comments:

- L151 “of CH4”

- L343 “types. And”

- Table 1, I miss the GSD parameter

- Figs.3 and 4: they should have a more similar format. Also, axis labels are missing in Fig.4.

- L656 FPA has been defined ealier in the text

- L778 and L785: two consecutive definitions of QC

- L895 TOA has been defined ealier in the text

- L978 “Condo”?

- L1010-1016: As the authors know, super-emissions in the Permian basin are typically short-lived. I don’t think that the 7 t/h source would have been active 15 days after the initial Tanager detection even if it had not been notified.

- Fig. 20, 21: ppm·m units should be used for consistency with the other figures and XCH4 maps

- L1210: “for an isolated of interest”

- Fig. 25, 26: they should have the same y-axis label; also, please, discuss the TTA peaks in the text.