

# Detailed Notes

## Section 2.4

Is the Distribution and Publication system mentioned in the text
supposed to be part of Figure 1, either as an umbrella term or a
(missing?) component?

** We have adjusted this figure to put the publication "customers" at
   the bottom and added a line to show where the distribution and
   publication mechanisms interface to these customers.

## Section 3.1

This is by no means necessary, but I'm curious to see a table or
discussion of what fraction of jobs of various types failed with bad
"quality". In other words, how much data could you not get through the
pipelines at all, and what was the most sensitive step?

** We liked this suggestion and added a subsection 3.12 and a new
   table (2) to discuss the failure rates.

## Section 3.3

Running "Registration" only once for each exposure would seem to
prohibit re-running "burntool" after updating the algorithm for that -
and I'm guessing you didn't get that fully stabilized until after you
had already processed some images and learned from thr experience. How
did that work?

** We added a couple of sentences to explain that we used a
   semi-manual task to re-run just the burntool analysis during
   development and if the code ever needs to be changed.

## Section 3.5

Why a 3rd-order polynomial from chip to focal plane? Wouldn't an
affine transform have been sufficient (and more than that degenerate
with the focal plane to sky transform)?

** We use the higher-order transformation for each chip to capture the
   small-scale astrometric signal present in the data.  One could use
   an afine transformation for chip-to-focal plane and capture the
   same signal in a much higher-order model for focal-plane to sky,
   but that was not our development path.  These would be equivalent
   solutions.  (Note that degeneracies exist in both cases).   We
   avoid the degeneracy of the chip positions in the focal plane
   solution by fitting the local gradient to get the initial
   distortion solution (and there are certain terms which are held
   fixed for the focal plane.)  We then limit the impact of the
   degeneracy by fitting the two levels independently and fixing the
   focal-plane solution after a few iterations.

   We have added some words to explain some of this, but leave the
   details to Paper IV.

What makes the masks generated in this step "dynamic"? Are they
generated wholly from the reference catalog (i.e.  predicting where a
ghost will appear based on the position of a bright star)? It seems
like the CAMERA step does not utilize any of the pixel data (just the
pixel-level masks from CHIP). Is that correct?

  ** correct: the dynamic masks are generated from the reference
     catalog and do not go back to the original pixels.  We added a
     paragraph to clarify.


## Section 3.8

Is the selection of which warped images go into a stack driven by
human operators, or are there automated systems to launch these jobs,
too?

  ** section 5.2 discusses how both the nightly stacks and
     large-scale reprocessing campaign stacks are automatically
     defined.  We added some words to refer to this section in 3.8.

## Section 3.10

How much of the PSF-convolved galaxy models do you re-fit in forced
photometry? If you're fitting more than just the amplitude at that
stage, and considering each exposure as independent, you're
potentially throwing away a lot of S/N (at least in the many-exposure
limit), even if you average later. If you're just fitting the
amplitude, the structural parameters are still going to be the ones
affected by poor PSFs in the stack.

  ** th


## Section 3.11

transient source -> transient sources

  ** fixed.

## Section 4.1.3

I was confused when first encountering the word "files" here because
up to this point I had been thinking of the DVO as just another MySQL
(or other SQL-ish) database, and I wasn't sure what kind of files were
being referred to. I think it'd be helpful to briefly describe the
overall architecture of the DVO as (mostly?) spatially sharded files
at the beginning of section 4, even if the details of the partitioning
aren't described until 4.1.3.

Missing punctuation in parenthetical HST GSC reference?

  ** fixed

