I’m trying to figure out what the total square degree coverage of the footprint is in v.3.2 My rubin_sim/MAF is rusty. Looking at http://astro-lsst-01.astro.washington.edu:8080/allMetricResults?runId=21#SRD%20FO%20metrics and I see that there is the f0 but that’s based on the SRD requirements. Is there any easy way to get the total square degree coverage of the v3.2 footprint for both the WFD and all of the footprint?
There’s not really an easy equivalent in our standard metrics.
However, I did add it to the bottom of this notebook - https://github.com/lsst/rubin_sim_notebooks/blob/main/maf/tutorial/Survey_footprint.ipynb
The short answer is that it’s about 33,500 sq degrees.
Do you have any suggestions @ljones for how I could adapt your cell in the notebook to calculate the total sky coverage each month in year 1? Thanks!
Ah, yes so … similar idea, but you can either simply calculate the metric using a sql constraint to use only visits within each of the more limited timespans (i.e. what I did in cell 51+ here - https://github.com/rhiannonlynne/notebooks/blob/main/Template%20Generation.ipynb) or you could make a new metric that would record the date that the healpix gets its first (or second, third,etc) visit. And then look at how much of the sky is covered by time X in the result (making new summary metrics, although you might be able to just modify the AreaSummaryMetric).
Meg, does this notebook help (https://github.com/jrob93/notebooks/blob/main/survey_coverage.ipynb)? It runs a count metric to get a number of visits per healpixel for successive times t<28, t<56, etc. in year 1 only. I’ve counted the number of healpixels that are not nan at each of these times, at least I think I have. I’m not the best at masked arrays and I see my values are different to Lynne’s…
BTW I’ve included an sql query in the notebook to exclude the deep drilling fields. I’m not sure how to do an sql query to keep just WFD visits. Is the WFD the visits with “pair” in the “note” field of the visit db?
Thanks. It looks like the output from cell 53 is exactly what I’m looking for. I think that is the total sky coverage per half month. Is that correct? 51 is doing the calculation in healpix 53 is adding up?
Cell 51 calculates the sky coverage in r band in half month increments; cell 53 looks at what part of the sky is covered with at least one (>0) visits and converts the length of the healpix array into area – so, yes.
@jrob93 I think your numbers are similar, although you’ve got slightly different days …
here’s mine next to yours …
so they’re pretty close (my “month” was 30 days long, so 1.0 = 30 which is 9002 for me and 28 has 8998 for you … likely 3.0 = 90 → 15470 vs 85 → 15368.
Oh, and your question about just calculating WFD visits … yeah, so the problem really is that “WFD visits” are poorly defined.
We do have some metrics that are intended to be defined on “the WFD”, so for these what I do first is define what the WFD area is (the area which receives at least 750 visits) – this gives you the area to consider (I actually set up a HealpixSubsetSlicer, so I only calculate metric values in this area, but there are multiple ways to do this). And then you can reject things like the neo_twilight visits as they’re shorter exposures (if you like, or possibly just count them as half visits) and reject DDF visits – both of these can be rejected via their notes, or a combination of note and exposure times.
The “pairs” alone doesn’t quite work, unless you explicitly don’t want to count visits taken during twilight ‘greedy’ time, and I don’t remember off the top of my head how the long gaps visits are reported (I think they have ‘long’ before ‘pair’, so ‘pair’ alone would miss these).
Thanks for the info Lynne, yes getting the exact WFD sounds a bit more complicated than I thought but I think i understand now. And thanks for checking my numbers