v1.1: add Hebcal-derived columns (shabbat_or_chag_exact, is_yom_tov, holiday)

README.md

@@ -113,7 +113,10 @@ The full set present in the dataset:
 | `dow` | int8 | Day of week, Mon=0 … Sun=6 |
 | `hour` | int8 | Local hour 0–23 |
 | `is_friday` | bool | `dow == 4` |
-| `is_shabbat` | bool | `dow == 5` (Saturday — proxy for Shabbat; see caveats) |
+| `is_shabbat` | bool | `dow == 5` (Saturday all-day — naive proxy) |
+| `shabbat_or_chag_exact` | bool | True between Hebcal-published candle-lighting (Friday or chag eve) and havdalah (Saturday or chag conclusion), Jerusalem times. The recommended Shabbat flag. |
+| `is_yom_tov` | bool | True on local dates that fall on a major Jewish holiday (Pesach, Shavuot, Rosh Hashana, Yom Kippur, Sukkot, Shemini Atzeret, etc.). |
+| `holiday` | string \| null | Name of any Jewish holiday or observance for that local date (e.g. "Yom HaAtzma'ut", "Erev Shavuot"). Joined with `; ` if multiple. |
 | `pollutant` | string | Source code (e.g. `NO2`, `PM2.5`) |
 | `pollutant_en` | string | English long name |
 | `pollutant_he` | string | Hebrew long name (as published by the source) |
@@ -171,16 +174,19 @@ methodology, caveats, and limitations is in `analysis/FINDINGS.md`.
 
 ## Caveats and known limitations
 
-- **Shabbat is approximated as the calendar Saturday in local time.** Real
-  Shabbat onset/conclusion is sunset-based and varies between roughly
-  16:30 and 19:30 across the year. A Hebcal-driven exact window would
-  tighten the signal, especially for the Friday-evening / Saturday-night
-  transitions.
-- **Jewish holidays are _not_ excluded.** The window 2025-04 → 2026-04
-  contains Pesach, Shavuot, the High Holy Days, Sukkot, Hanukkah and
-  Purim. Yom Kippur in particular is the cleanest air day of the year
-  nationally and biases any "weekday" baseline that includes it
-  (Wed 2025-10-01 was YK 2025).
+- **Two Shabbat flags are provided.** `is_shabbat` is the naïve calendar
+  Saturday (Sun=6, Sat=5) and is included for backwards compatibility.
+  `shabbat_or_chag_exact` is the **recommended** flag — it uses Hebcal's
+  Jerusalem-specific candle-lighting (Friday eve, 40 minutes before
+  sunset) and havdalah (≈42 minutes after sunset, three medium stars)
+  times, and also covers Yom Tov days. There is a single set of
+  Hebcal times applied to all stations; intra-Jerusalem variation is
+  under one minute and not material for hourly analysis.
+- **Jewish holidays are flagged but not removed.** Use `is_yom_tov` to
+  exclude the seven major Israeli yamim tovim from your weekday
+  baseline; use `holiday` to filter by name. **Yom Kippur in particular
+  is the cleanest air day of the year** (Wed 2025-10-01 was YK 2025);
+  leaving it in inflates the apparent cleanness of the weekday baseline.
 - **Sensor validity flag is trusted as-is.** Only `valid: true` readings
   are included; the source system's QC decisions have not been
   re-verified.
@@ -204,5 +210,16 @@ source.
 
 ## Versioning
 
-- **v1** (2026-04-28): initial release. 12 months × 5-min × 12 stations,
+- **v1**   (2026-04-28): initial release. 12 months × 5-min × 12 stations,
   long-form parquet.
+- **v1.1** (2026-04-28): adds Hebcal-derived columns
+  `shabbat_or_chag_exact`, `is_yom_tov`, and `holiday` for
+  Jerusalem-precise temporal filtering. Underlying readings unchanged.
+
+## External data sources
+
+- **Air-quality readings:** Israeli Ministry of Environmental Protection
+  (<https://air.sviva.gov.il/>).
+- **Shabbat candle / havdalah times and Jewish-calendar metadata:**
+  [Hebcal](https://www.hebcal.com/), public REST API,
+  Jerusalem (geonameid 281184).

data/readings.parquet

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
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-size 30535208
+oid sha256:6433516dce7fd0830315acb84d75bf79ddb48b9605c7474b8adcb5d0d5d9aa6e
+size 30623321