
Referee Report
Reviewer's Comments:
This is an important piece of work to be published as the last of
a set of seven papers describing the Pan-STARRS-1 survey and
data release 1. It represents a substantial body of work over
many years. There are no major revisions requested, but there
are quite a number of suggestions to further improve the clarity of
the presentation.

The authors could present early in the paper that the goals of the
accuracy for photometry and astrometry of stars has indeed been
achieved, with quantitative estimates of the accuracy as presented
in other PS1 papers, or even by others is comparisons to external
data sets.

** added to the end of Section 3 Psphot Design Goals

For many of the sections, the reader would benefit by starting with
more of a description of the intention of the algorithms described.
For example:

- Section 4.1: The initial source detection is appears intended is
identify bright point sources and omit extended sources. That should
be stated, along with the goal of providing sources for the PSF modeling.

** Added introductory sentences in 4.4.1 and expanded 'intial source
   detection' bullet in 4.1.

- Section 4.4.3: The purpose of the moments is to identify problematic
sources and to measure Kron magnitudes. The importance of the Kron
fits isn't revealed until much later in Sec 4.6.5 in determining the
classification of sources. This importance of Kron fits should
therefore be described much earlier, and the rationale for using
this for classification since it is typically a noisy measure.

** Added addtional explanation for the uses of the second and higher
   order moments in the introductory paragraph.  Added a note about
   star-galaxy separation when Kron magnitudes are first discussed.
   Also added a paragraph to describe the original motivation of the
   higher-order terms (identify collimation and alignment failures),
   but notes that this has not panned out as hoped.  Also added a
   short justification in section 4.6.5

- Section 5: The extended source photometry has not been motivated
and it is unclear what the goals are for those objects.

** added motivation in introduction of section 5.

The text doesn't explain how in general bad (saturated, light traps,
masked) pixels are treated in the image. Presumably, these must be
replaced with some value to allow measurements of some if not all
of the source properties described in the paper. The large number
of bad pixels is a motivation for all of the averaged quantities
in Section 6, so it should be presented what fraction of pixels
are compromised and what fraction of objects are compromised in
individual images.

** we do not interpolate or replace masked values; instead they are
   ignored in model fits. their presence affects aperture-like
   measurements, and we rely on averaging (as mentioned) to overcome
   the masking.  We also provide the PSF_QF and PSF_QF_PERFECT values
   to assess the impact of masking on a specific source.  Text added
   to this effect in section 4.3

The paper should identify which of these measurements and tabulated
mask values appear in the DR1 and DR2 data releases. For example,
Tables 1-4 must refer to some named quantities in the data releases.
This paper should also clearly indicate which quantities are recommended
to be most reliable for point source astrometry, fluxes and colors.
(My guess would be the astrometry from the stacked images in Sec 4.7, since
those aren't recomputed; fluxes from the averaged forced photometry
in Sec 6; and colors from either aperture photometry on the stacked
images or from the averaged forced photometry, and the authors must
know which is demonstrated to be more reliable). The paper should
state the same for galaxy astrometry, fluxes and colors.

** for each section, we have added a summary of where the values may
   be found, and added an overall summary of this issue to the end of
   the Basic Analysis section.

A detail of the code is presented (variable names, etc) that imply
that the code would be publicly available. Is it, and if so where?

** Added a link to the URL where the software can be downloaded

The other PS1 papers are discussed in the introduction, but not
otherwise referenced throughout the paper. Some notable places
where references to these other papers in the series should be made:

- Sec 5.5, where the typical stellar detection limits are quoted

** Added reference to Paper I for this

- Sec 6, which of these averaged photometry measurements are used in
the PS1 global photometry solution, and which papers demonstrate
that the photometric goals are achieved

** added comparion discussion of chip, warp, stack photometry at the end of Sec 6.1

- Sec 7, where the image differencing detections and photometry is used

** Price & Magnier is cited, but this has not yet been submitted (not
   part of this series)

A handful of places use lower-case "psf" (Table 2 and pg 13) and
should be written "PSF" for consistency. "chi-square" is used
both lower-case and upper-case.

** Fixed these for consistency

A number of places refer to starting guesses for ML minimizations
(search for "guess" in the text to find these). It would be useful
to provide the formulae for these initializations (and potentially
necessary if one were want to repeat the fits).

** Added a discussion of the PSF parameter guesses in section 4.5.3,
   expanded discussion in section 5.3, referring back to 4.5.3.

Although this paper is primarily meant to present the decisions made
in the calculations presented in the PS1 catalogs, the authors should
consider including a section about any different choices were they
to start such an effort in the future. There are a few places within
the text where they allude to such things, but collecting these thoughts
in one place would be a useful service.

** added suggested improvements in conclusion

Abstract:
- This abstract states this is the version used for the "first public
release" of the data, but the text says this was used for both
DR1 and DR2. Suggest explicitly stating this was used for Data Releases
1 and 2.

** fixed in abstract

Intro:
- "...and include an improved calibration of the PV3"
Please specify if this is limited to the photometric calibration,
or astrometry or any other parameters as well.

** clarified in Intro, paragraph 5.

- Intro should state that this analysis is applied to individual images,
image stacks, and image differences (if true), and if the Medium Deep
Field program makes use of the same code.

** clarified in Intro, par 6

Sec 2:
- For the photometric accuracy goal, it's not stated here whether
the 1% number is absolute or relative. Presumably, it's the relative
photometry requirement that would be applicable to this work.
(This is repeated in Sec 3.)

** The goal was for accuracy within the Pan-STARRS photometric system,
   but the requirement on the tie to the absolute flux system was not
   as stringent.

- IPP should be defined at first mention.

** defined in Intro par 7

- "CHIP analysis stage" is mentioned without definition.

** defined in Background, par 6 (2nd after the bullets). 

- For all of the "psphot" variants described, it would be of interest
whether the various input images are required to be pixel-aligned.

** clarified in Background, par 7 for psphotStack, reworded the
   description for the basic psphot to clarify (Background, par 6),
   added the word 'co-aligned' for psphotFullForce (Background, par 8)

- Single-epoch images and stacked images should be explicitly defined here
(not just the code that acts on them). There are some instances later
that refer to "CAMERA", "CHIP" and "STACK" (upper-case), and common terminology
should be used throughout. The usage of "CAMERA" and "CHIP" seem to be
the same, but maybe they aren't?

** Our typography is to write the major IPP analysis stages in
   small-caps (CHIP, STACK, etc).  We added some words to Background,
   par 6 to (minimally) define the stack stage and products.  We also
   added a desription of the typographic choices (end of Intro).
   Replaced Camera in a couple of places where the text should have
   referred to the CHIP stage.  (Table 1 and Sec 4.8, par 5).

Sec 3:
- The overall design goals aren't stated: fluxes and positions for stars;
fluxes and positions and shape parameters for galaxies suitably for
weak lensing measurements; detection and measurements of transient
sources for use by the Moving Object Pipeline for asteroids and supernovae.

** good point: we added an intro paragraph to Sec 3 to explicity state
   the top-level design goals.

- The astrometry and photometry goals are likely written for stars,
not galaxies. It should be explicitly stated the the quantitative goals
are for the contributions to the errors beyond the statistical errors
(it looks like you disfavor the term systematic errors?)

** added text to specify that these are goals for bright stars where
   photon noise is small compared to the systematic errors.

- "astrometric accuracy goal" -> "relative astrometric accuracy goal"

** fixed

- "requirement" -> "goal" to be consistent with the text elsewhere

** fixed, and cleaned the introduction sentence of 'requirement' vs
   'goal' confusion.

Sec 4:
- As a reader, I found it confusing to keep track of which measurements
are only being made on the brightest 20-sigma sources, vs. the fainter
5-sigma sources. For example, Sec 4.6.5 discussing doing fits to "all
sources", but I think this might still only be to the 20-sigma detections?
Consdier splitting this Sec 4 into two sections, one with all the subsections
applying to bright sources, and another addessing all (==faint) sources.

** We have expanded the discussion in 4.7 (Faint Source Analysis) to
   explain which of the steps in the bright source pass are repeated
   and which are skipped.  We refer back to the specific sections and
   explain where there are detailed differences in the bright and
   faint versions of the same step.

Sec 4.1:
- This overview describes the PSF model class as being defined in step 3,
but reading the text it appears that a set of PSF models are determined
there and it is only during the faint source analysis (see very end
of Sec 4.8) that the PSF model for an image is actually selected.

** The aperture correction is measured at the end of the bright-star
   pass, at which point the PSF model is chosen and fixed for the rest
   of the analysis.  A final aperture correction is measured at the
   end of the full analysis, but only for the PSF model class selected
   earlier.  But for PV3, the PDF model was fixed to the PS1_V1
   version, so this selection was not performed. We have added text to
   4.5.3 to explain how the aperture correction is used to select a
   PSF model, and that only the single model form was used for PV3.
   We also note in section 4.8 that we re-measure the aperture
   correction at the end with the other sources subtracted.

Sec 4.3:
- It would be of interest to state whether the convention is used for
the images to be in units of ADU, electrons, or some other physical unit
(albeit only approximately, owing to flat-fielding, etc).

** IPP normally uses ADU (digital numbers), but psphot could be used
   with other units if the variance is consistently defined.  Added
   text to this effect.

- Table 3 needs to be explicitly referenced in the 2nd paragraph.

** added

- Superpixels are defined in this section as something used for the sky
fitting, but in fact are used in other contexts, so it would be
good to define it as such and also state the typical physical scale.

** added text to explain the difference between the sky superpixels,
   the PSF parameter variations, and the thread assignment superpixels.

- The sky fitting scale length of 400 pixels should be expressed
in arcsec as well, and some discussion for the trade-offs in this choice.
Are there any instrumental effects (ie, vignetting gradients) effecting
this choice, or only sky and astrophysical?

** added a paragraph to describe the rational for the choice of the scale

- There must be an estimate of the accuracy of the mean sky heuristic,
perhaps as just the step-function-difference of when the more complex
measure is used.

** added a table showing sky recovery vs stellar density from
   simulations using the standard psphot analysis vs other methods,
   added discussion of the results.

Sec 4.4.1:
- For those readers unaware, the first paragraph could explain that
in the limit of a Gaussian PSF and isolated sources, this is the
optimal detection algorithm. Then the choice of approximating the
PSF by a Gaussian for the convolution is presumably to allow the
fast compution by having a kernal that's separable in x&y.

** added text to explain that this is an optimal detection for sources
   matching this PSF, but that since our goal is brighter sources, the
   choice of smoothing function is not critical.  The smoothing at
   this stage is to reduce the impact of pixel-to-pixel scatter on the
   initial detections.

- Par 2 should start by saying the intention is to uniquely identify
peaks. The last sentence is missing some words.

** clarified this 

Sec 4.4.2:
- Should be stated here and in the Fig 1 caption if these aren't
straight line paths. Also, which path is chosen in the event
that there are several?

** noted in text and caption that the real paths are 2D, while the
   figure is a 1D illustration.  also noted that the code looks for
   any key col between peaks that are above a threshold, thus the
   highest one matters.

Sec 4.4.3:
- "sigma_PSF which different" -> "sigma_PSF, which is different"

** fixed

- "and a trend this the" -- fix wording

** fixed

- semi-colon should be period before "The sums"

** fixed

- "be a large amount" -> "by a large amount"

** fixed

Sec 4.5.1:
- PSF variations are due to optical aberration (and defocus), not-flatness
of the CCDs, and atmospheric variation. It would be good to tell the
reader the typical scale and amplitude of variations due to each of these.
This may even warrant inclusion of on image of the PSF width variations
for a typical exposure.

** we have added a figure to show examples of the image quality
   variations observed in PS1 in both good and bad seeing data.

- Please state whether the PSF model is this set of formulae
evaluated at the pixel centers, or must be integrated over the pixel,
and the reason for the choice.

** @ pixel centers (added sentence)

- There are a few uses of "interpolation" in this section, the first
use is presumably "linear interpolation", but the details of this
for PSF interpolation are worth describing.

** reworded to note that bi-linear interpolation in used

- The last paragraph and formula in this section is inscrutable as
R,R_0,R_X,... are undefined.

** reworded to explain that these are the linear fit parameters for each pixel in the residual mode.

Sec 4.5.2:
- Since the GAIA catalog is now available, an interesting question is
whether using that catalog for PSF star selection would be preferable
to the heuristic of selecting such stars from the PS1 data. An interesting
metric would be the fraction of PS1 PSF stars are confirmed to be point
sources by GAIA.

** This is an interesting suggestion, but out of the scope of this
   effort.  we have added this to the lessons-learned discussion

Sec 4.5.3:
- Please present the number of grid cells in these fits also in terms
of the physical scale (in arcsec) on the sky for those grids. Both
in the text and Table 5. This can be tied back to the requested
description of the expected PSF variations in Sec 4.5.1.

** adding in table in the the introductory text in section 4.5.1.

- As discussed at the start of this report, the handing of masked
pixels should be descsribed here. Some measurements (such as aperture flux)
are formally undefined with even a single masked pixel; are those reported
as undefined measurements, or are they measured with the pixels first
replaced based upon interpolation or linear prediction or some other method?

** We provide the PSF_QF and PSF_QF_PERFECT statistics to assess the
   impact of masking on the aperture-like measurements.  Added some
   additional explanation in section 4.5.3

Sec 4.5.3:
- "smf/cmf files" are not defined or referenced anywhere else in this paper.

** removed the jargon and replaced with 'output FITS catalog files'

PSPS if referred to few enough instances (3) in the paper, that it could be
explicitly defined in each of those instances. The term "public" here
isn't what many people would expect, so should be defined as public to
the other code.

** By adding more explanation of the data products, we have added
   references to PSPS.  We have now added a new paragraph in the
   introduction to explain this subsystem and its relationship to the
   public releases more clearly.

Sec 4.6.4:
- "times" -> "\times"

** fixed

- Not clear why the geometric mean trick is necessary in this calculation
to reduce blending issues if neighboring sources have already been subtracted.

** only PSF models have been subtracted at this point, so galaxy
   neighbors tend to leave behind a lot of contaminating flux.  Explanation added to text.

Sec 4.5.4:
- The term "size class" is only used once here, so perhaps only use
the term "classification".

** reworded to make this clearer.

Sec 4.6.5:
- PSPHOT.EXT.NSIGMA.LIMIT is the only variable that looks like this
in the paper, and isn't defined in the tables.

** we added an explanation at the end of Section 1 that the
   configuration variables, in fixed-width font, have the PV3 value
   listed after them in parenthesis.  We have also made the text more
   consistent about how this appears throughout the tex.

- Explicitly state that the cosmic ray identification is based upon
sources appearing more morphologically compact than the PSF.

** done in 1st paragraph

Sec 4.6.6:
- This section should be greatly clarified. It sounds like the intention
was to perform the same joint fit as described in Sec 4.6.1, and it's not
clear why this was something different. The current text reads as if
it's a single iteration of fitting one star at time, subtracting fits
only to brighter neighboring stars. The paragraph beginning "Sources
which are blended..." should be relegated to the end of the section,
and presented as a future development effort.

** reworded to explain that this step, unlike 4.6.2, does a
   simultaneous fit to the position and normalization for sources
   one-at-a-time.

- Remind the reader that the 4 independent parameters includes a local sky
value.

** in fact, we do not allow the sky to float; fixed the wording to
   specify the *3* independent parameters and to explain why we do not
   allow the sky to float.

- "remaining flux should be below 1\sigma significance" ->
"remaing flux divided by the errors should be normally distributed about 1"

** fixed wording 

Sec 4.6.7:
- This double-star case would be a common and interesting case, and it
is worth demonstrating the validity of this approach. No doubt simulations
were run showing this approach works for some separation and flux ratio
range.

** In reviewing the code, we discovered that this approach to close
   neighbors was turned off for PV3, similar to the blend fits
   discussed above.  We have moved both of these crowded field
   analysis concepts to a single section, identified as deactivated
   for PV3.

Sec 4.7:
- Completeness and purity should be discussed here. Even if this is
more fully described in another paper, a summary of those findings
could be included here.

** This was a definitely gap.  We have added a subsection (4.9)
   discussing the completeness and contamination, using both simulated
   and real data to illustrate these effects

Sec 4.8:
- The pronouncement that the wings of the PSF do not change significantly
or quickly should be backed up with a reference, if possible. I'm not
aware of a thorough study of this (although there may be one), and the
PS1 data may be the best data set to ask these questions.

** The argument in the paragraph, that photometry using a large
   aperture can correct the PSF photometry, does not really depend on
   the stability of the wide wings as much on the small fraction of
   light in the wings.  Since we could not back up the statement about
   the source of the wide wings (and Saglia et al 1993 shows some
   variations in the wings of MDM 1.3 and JKT 1m data), we have
   removed that part of the argument and simplified that paragraph. A
   larger study of stellar profiles from PS1 on large scales would be
   interesting, but beyond the scope of this papper.

- "ApResid" is only sort of defined implicitly.  

** The choice of PSF model form is actually made early on, after the
   first pass on bright stars (section 4.5).  The choice of the model
   is based on the psf - aperture (ApResid) residual scatter.  The
   discussion of the model selection at this point in the paper was an
   artifact of an attempt to consolidate the discussion of the
   aperture correction with the earlier aperture photometry.  We've
   fixed the text to leave the discussion of the selection of the PSF
   model form in section 4.5 and leave 4.8 to the calculation of the
   aperture correction for the photometry.  As a result, we eliminate
   the term ApResid entirely.

- It's interesting that the choice of the PSF model is made based upon
the fainter, not the brighter, stars.

** this is not the case, but the organization made it seem that way.
   See previous comment.

- An interesting result is the fraction of images that use each of the
PSF models, and whether that strongly depends upon the density of stars
and/or filter, or to what extent a similar image requires a different PSF
model owing to atmospheric variations. For example, in the following
section 4.9, has the same PSF model class been automatically selected
for all 18 images?

** This would be very interesting, but unfortunately we only used the
   single functional form PS1_V1 for all of the PV3 analysis.  We've
   added text to section 4.5 to state that explicitly.

Sec 4.9:
- A very interesting quantitative result that could be shown here is
the variation in bright star magnitudes using aperture photometry.
This would be a measure of the site's atmospheric transparency variations.
There are results for this presented in the conclusions of an earlier PS1
paper ("Photometric Calibration..."), but those ~10 mmag numbers may
be dominated by the PSF mis-estimation of bright stars rather than the
atmospheric transparency variations.

** we have added discussion and some plots showing the repeatability
   of the brightest stars for PSF and aperture magnitudes.  We also
   discuss the long-term site characteristics and the impact of the
   atmosphere on the photometric calibration, relating back to the
   ubercal work of Schlaley et al 2012.

Sec 5:
- "to all object" -> "to all objects"

** fixed

- The definition of where in Galactic coordinates extended source photometry
is performed is a little confusing. If the "l" in the in-text formula
is galactic latitude, is it really the case that no extended source
photometry is performed within 65 deg of the galactic center?
Is this decision made for all sources within the same image, or is
the decision made object-by-object?

** The avoidance contour approaches a constant Galactic latitude far
   from the galactic center, but rises in a Gaussian shape to avoid
   the bulge, with the max avoidance latitude of 35 degrees at
   Galactic longitude of 0.0.  We have added a small illustration of
   the cut, and noted that the cut is applied on an object-by-object
   basis.

Sec 5.2:
- The argument is that the surface brightness *profile shape* is conserved,
not that the surface brightness is conserved with distance, which of
course it is not.

** right, fixed wording

- It may be useful to point out that these choices of Petrosian parameters
to evaluate (R50 and R90 using circular aperatures) appears to be the same
as those in the SDSS catalogs. Can one expect those quantities to
compare well to those in the PS1 catalog?

** These agree to first order, but there is a tendency for the PS1
   measurements to have larger radii and smaller (brighter)
   magnitudes.  Added text and a figure to illustrate

Sec 5.3:
- Equn 28 is a blank line

** fixed

- Equn 27 would conventionally be written after equns 29-32 as "with
the definition f_p=..." (remove the word "simplify").

** re-written as suggested

- "and/or" -> "or" ?

** fixed

- "In the analysis, convolved galaxy fit..." -> "In the convolved galaxy fits..."

** fixed

- Graham & Driver missing in the References

** fixed

- For the approximation of the central pixel values, the maximum fractional
error of this approximation should be stated.

** In trying to answer this question, we realized that, while we
   experimented with this technique, the as implemented psphot in fact
   used brute-force numerical evaluation.  These implementation
   experiments did not pan out so we went ahead with something that
   worked, even if it was slower.  We have updated the text to
   describe the actual implementation.

Sec 5.4:
- It's not clear what happens with poor-quality (worse than 1.5 or 2.0
arcsec seeing) images. Have they been included in the image stack, and
the assumption made that the stacked seeing is always better than that?

** We do not exclude images with seeing larger than either 1.5 or 2.0
   arcseconds, but if the images are larger than the convolution
   target, they are not convolved.  We have added text to explain this
   and pointed out that stacks with FWHM larger than these limits will
   suffer seeing effects in the smaller apertures.

- It's convenient that the aperture fluxes are made with the same choice
of radii as used in SDSS. However, it should be noted here that the
SDSS aperture fluxes in the SDSS catalogs are computed without any
convolution. Since the median SDSS seeing is ~1.5 arcsec, those may
be expected to compare well with the 1.5-arcsec convolved PS1 aperture fluxes.

** good point, we noted this in the text

Sec 5.5:
- State the seeing of these simulated images.

** added

Sec 6 and 6.1:
- These sections could be clarified by splitting the sections, and
calling the section something like "Averaged Single-Epoch Measurements"
(where single-epoch could be "warp image" or whatever appropriate). Forced
photometry is only performed on the stars, and it's something very
different from the galaxies. The lensing subsection isn't "photometry"
at all. What all 3 subsections have in common is that measurements
are made on all of the single-epoch images, and then those measurements
are averaged.

** We agree that the organization of this section could be improved,
   but we disagree a bit with the proposal.  We consider all of these
   analyses to be forced in that the fits are highly constrained by
   the stack priors, with their positions (for PSFs and the lensing
   anaysis) and most of the structural parameters fixed.  In the
   extended galaxy analysis, each of the grid steps is completely
   forced, just like in forced PSF photometry.  By using the term
   'forced' to describe this process, we would like to make it clear
   that, for each grid position, the parameters (except normalization)
   are completely constrained.

We have renamed Section 6 as Forced Warp Analysis and split out the
PSF vs extended source analysis sections as recommended.  We added
some explanation at the end of the section to explain what we mean by
'forced'.

- The general description of the section should end with "variant of psphot",
with the motivation being written such that it applies to both the
averaged forced photometry on stars and the averaged single-epoch fits
for galaxies

** see previous

Sec 6.1 (now 6.2):
- CFHT, COSMOS should have citations to the relevant publications
discussing their stacked images. There are multiple possible references
for the mathematical appropriateness of image stacking, a nice recent
discussion would be Zackay & Ofek 2016.

** added references and updated the text

- The terms "skycell" and "warp image" are first used here without
definition. Are warp images the same as CAMERA and CHIP?
** Updated Section 2 to outline the relevant processing stages and
define 'warp', 'skycell', and 'stack' more cleanly.

- For the forced photometry on single epoch images, is this a joint
fit for overlapping objects?

** for the galaxy models, no.  The galaxy model fits are measured on
   each object with the other objects subtracted.  Text added to this
   effect in Section 6.1

Are overlapping galaxy models subtracted first? 

** yes, see above.

"The PSF model is fitted..." -> "The amplitude of the PSF model is fitted as the flux..."

** fixed the wording here and also clarified below that we measure
   Kron and aperture fluxes as well.

Sec 6.2 (now 6.3):
- The reader only learns in the last few sentences that lensing
parameters are an average of all of the single-epoch measurements.
This should be stated upfront, and then again at the end of the subsection
clarifying how the PSF systematics are removed.

Phrases like
"interpolated PSF ellipticities" are confusing, when I *think* what's
being used are "interpolated star ellipticities".

** reworded this to make the analysis clearer

- Was this lensing code used in any of the GREAT challenge papers,
and if not, which code would it be most similar to?

** psphot was not used in any of the GREAT challenges, but is similar
   to the EPFL_KSB team's code.  added this to the text

- Define "KSB" and "HFK" references in-line

** done

- "ie,," -> "ie,"
" absoluate" -> "absolute"

** fixed both

Sec 7:
- This section is more cursory than the other sections. It's not clear
how the end user should identify high-confidence asteroid or comet
detections, and the completeness and purity of such detections.
If these questions are covered in other Pan-STARRS papers, please reference
them here.

** extended the background description, and referred to the previous
   work on asteroid and supernova detection within Pan-STARRS.

- A basic piece of information that should be given is whether the differencing
is performed on pairs of images, or single (warp) images compared to
image stacks.

** we generate difference images for warp pairs, warp-stack, and
   stack-stack.  Added this to the introductory paragraph in section 7

- "model from is" -> "model is"

** fixed

Conclusions:
- The PS2 telescope is only mentioned here. At least give a reference.

** added mention to Intro & added appropriate references

Tables:
- For all of the tables, a caption should be included that explicitly
describes all of the columns. Some readers will be using these papers
as reference material, in which case the tables should be self-explanatory.

** Extended the table captions as requested.

Tables 2,3,4:
- Please provide the names of these masks in the data products. From the
text, the only mapping I could figure out is that Table 3 corresponds
to "mask2".

** added to the table.

Figures:
- For all the multi-panel figures, typical style would be to label
each of the sub-panels (a), (b), etc, and describe in the caption.

** fixed for Figures 2, 5, 6, 8, 9, 10

Figure 2:
- "window" in the figure text should be "\sigma_w" to be consistent
with the caption and text.

** fixed, and cleaned up the figure appearence a bit (font sizes)

- For Figures 2,5,6, please do the mathematical calisthenics of stating
how these instrumental magnitudes can be read as magnitudes above the
detection threshold. If possible, it would be preferable to convert
these figures to threshold magnitudes as done for Figure 7.

** fixed for Figures 2, 5 & 6

Figure 3:
- This figure isn't referenced in the text.

** referenced in Section 4.5.1, second paragraph after list of model equations

- State if each point is a single pixel value.

** added to caption

- State whether the black line model is part of the PSF models for these
particular stars

** the lines are a 1D average of the PSF models fitted to these stars (added to caption)

Figure 4:
- State that this is for one image (or image stack?), with each source
denoted by a point.

** updated the caption

Figures 5 and 6:
- I can't find a definition of "STS" anywhere in the text.

** reworded to remove the acronym

- Upper panels should be labeled "Number of stars".

** fixed

Figure 7:
- Caption should specify the seeing of these images (not in the text either).

** added to caption and text

Figures 8 and 9:
- These figures need much more explanation. The upper-left panel is
presumably an RMS of the total magnitudes from the simulations?
The upper right panel shows "ellipticity", which is not a defined quantity
in the text. The other 4 panels could refer to the explanation in Sec 5.5.

** captions update to be more informative.

References:
- It would be helpful to append "[Paper I]", "[Paper II]", etc, to
the references for this sequence of papers.

** added

- It would be helpful to append "[KSB]" and "[HFK]" to those references
since they are cited that way in the text.

** done

- Some additional references should be included; some suggestions above.

** added additional references

** Also, we have added Danny Farrow (UK Durham & MPIA) to the authors
   list for contributions related assessment of the galaxy model quality.
