Optimizing hydroxyl airglow retrievals from long-slit  astronomical spectroscopic observations

Franzen, Christoph; Hibbins, Robert Edward; Espy, Patrick Joseph; Djupvik, Anlaug Amanda

doi:https://doi.org/10.5194/amt-10-3093-2017

Articles | Volume 10, issue 8

https://doi.org/10.5194/amt-10-3093-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/amt-10-3093-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 10, issue 8

Research article

|

25 Aug 2017

Research article |

| 25 Aug 2017

Optimizing hydroxyl airglow retrievals from long-slit astronomical spectroscopic observations

Christoph Franzen, Robert Edward Hibbins, Patrick Joseph Espy, and Anlaug Amanda Djupvik

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Final revised paper (published on 25 Aug 2017)
Preprint (discussion started on 22 Mar 2017)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'The airglow and temperature in mesopause region', Anonymous Referee #2, 05 Apr 2017
- AC1: 'Re: Optimising hydroxyl airglow retrievals from long-slit astronomical spectroscopic observations', Christoph Franzen, 22 Jun 2017
RC2: 'Interactive comment on "Optimising hydroxyl airglow retrievals from long-slit astronomical spectroscopic observations" by Christoph Franzen et al.', Anonymous Referee #1, 11 Apr 2017
- AC2: 'Re: Optimising hydroxyl airglow retrievals from long-slit astronomical spectroscopic observations referee #1', Christoph Franzen, 22 Jun 2017

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Christoph Franzen on behalf of the Authors (27 Jun 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (29 Jun 2017) by Lars Hoffmann

RR by Anonymous Referee #1 (11 Jul 2017)

Suggestions for revision or reasons for rejection

Review of revised manuscript of "Optimising hydroxyl airglow retrievals from
long-slit astronomical spectroscopic observations" by Christoph Franzen et al.

The new version of the paper has significantly improved in comparison to the
previous submission. For the latter, I sent a long list of comments since the
short paper did not discuss the approach and the results in a satisfying way.
Overall, my comments have been answered thoroughly. The related changes in
the paper have improved the comprehensibility and have led to a more careful
and balanced discussion of the results. The latter is important since the
discussion is only based on three spectra in different near-IR bands with
exposure times of 10.8 s. Therefore, it is out of the scope of the paper to
provide conclusions on the quality of OH-based temperature gradients,
especially if non-LTE effects cannot be handled. The focus should be on the
description of the available data, their processing, their analysis with
respect to OH emission, and an overview of the scientific questions that can be
studied under consideration of the possible limitations. The new manuscript
sufficiently fulfils these criteria. Hence, the paper can be published in AMT.
However, for this, I have a few, mainly technical, comments, which should be
considered first.

Abstract: Despite the major changes in the text, the abstract is still the same
(except for a single word). Please check carefully whether the current abstract
still agrees with the rest of the paper. For example, note that the reported
error of about 0.5 K is smaller than all uncertainties in Fig. 5. The best
accuracy seems to be 0.7 K, which was achieved for OH(5,3). The uncertainties
for the other bands appear to be significantly larger.

P. 3, L. 13 and P. 5, L. 28: In the response to my comments, it was stated that
the observed astronomical object is not a (telluric) standard star. However,
the confusing term is still used in the paper at two positions. In astronomy,
standard stars are only observed for data calibration and processing.

P. 5, L. 21 and P. 14, L. 2 (Fig. 3): The rotational temperature for the
OH(5,3) band has changed in Sect. 3.1 but not in the caption of Fig. 3. This
discrepancy has to be corrected. If I interpret the response letter correctly,
the change is related to a modified approach for the relative flux calibration.

P. 6, L. 27: The most critical molecule for the absorption of OH(8,6) lines in
the lower atmosphere is CO2. There are no CO lines in the relevant wavelength
regime.

P. 14, Fig. 4: The caption of this figure has improved. However, it could be
even better if it was directly stated that the labelled tickmarks only provide
rough positions of the corresponding lines.

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ED: Publish subject to technical corrections (11 Jul 2017) by Lars Hoffmann

AR by Christoph Franzen on behalf of the Authors (18 Jul 2017) Author's response Manuscript

Short summary

We discuss a technique to extract the hydroxyl (OH) airglow signal from routine astronomical spectroscopic observations from the Nordic Optical Telescope. Emission spectra from the vibrational manifold from v′ = 9 down to v′ = 3. The fitted rotational temperature distribution with v′ agrees with model conditions and the preponderance of previous work. We highlight the potential for archived and future observations with unprecedented spatial and temporal resolutions.