Add fe-map and iss sources, The Shape of Distance as published, contribution guide

- femap/: planar best-effort solver, build, result and page (fe-map.aethercosmology.com)
- satellites/: The Sync Test build, ISS elements, SatNOGS timings and page (iss.aethercosmology.com)
- src/handoff/The_Shape_of_Distance_PRESENTATION.html: inputs for both
- CONTRIBUTING.md; README and LICENSE-DATA cover all four sites; GitHub mirror for issues and pull requests

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

satellites/satnogs.py

@@ -0,0 +1,68 @@
+"""SatNOGS facts quoted on the page, from the "Listening to the ISS" tab of
+The Shape of Distance (src/handoff/The_Shape_of_Distance_PRESENTATION.html,
+page 3; recordings of 3 October 2026 at 437.55 / 437.80 MHz).
+
+  python3 satnogs.py   -> data/satnogs_20261003.json
+"""
+import base64, datetime as dt, json, os, re
+import numpy as np
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+PRES = os.path.join(HERE, "..", "src", "handoff", "The_Shape_of_Distance_PRESENTATION.html")
+BURST_T = -10.0      # s from the Europe pass epoch: the instant compared across receivers
+
+
+def page3():
+    s = open(PRES, encoding="utf-8").read()
+    blobs = re.findall(r"[A-Za-z0-9+/]{20000,}={0,2}", s)
+    html = base64.b64decode(blobs[3]).decode("utf-8")
+    assert "<title>Listening to the ISS</title>" in html
+    js = re.findall(r"<script[^>]*>(.*?)</script>", html, flags=re.S)[0]
+    return json.loads(js[js.index("{"): js.rindex("}") + 1])
+
+
+def main():
+    D = page3()
+    out = {"source": "The Shape of Distance, Listening to the ISS (https://distance.aethercosmology.com/#doppler)", "passes": {}}
+    for key, p in D["passes"].items():
+        st = p["stations"]
+        dt0 = np.array([s["t0"] - s["pub"]["t_ca"] for s in st])
+        V = np.array([s["V"] for s in st]); E = np.array([s["V_err"] for s in st]); w = 1 / E**2
+        down = [s["t0"] for s in st]
+        out["passes"][key] = {
+            "utc": dt.datetime.fromtimestamp(p["t_epoch"], dt.timezone.utc).strftime("%Y-%m-%d %H:%M UTC"),
+            "stations": len(st),
+            "t0_rms_s": float(np.sqrt((dt0**2).mean())),
+            "v_kms": float((V * w).sum() / w.sum() / 1000),
+            # point beneath the station at each receiver's closest approach (published orbit)
+            "ca": [[s["pub"]["lat"], s["pub"]["lon"], s["t0"]] for s in st],
+            "offset_sd_median_hz": float(np.median([s["offset_sd"] for s in st])),
+        }
+    allV = np.array([s["V"] for p in D["passes"].values() for s in p["stations"]])
+    allE = np.array([s["V_err"] for p in D["passes"].values() for s in p["stations"]])
+    out["v_kms"] = float((allV / allE**2).sum() / (1 / allE**2).sum() / 1000)
+    # one instant of the Europe pass: carrier-corrected shift at every receiver with data within 3 s
+    p = D["passes"]["2026-10-03_Europe"]
+    shifts = []
+    for s in p["stations"]:
+        pts = np.array(s["pts"]); t = pts[:, 0]; i = np.searchsorted(t, BURST_T)
+        if 0 < i < len(t) and t[i] - t[i - 1] < 6:
+            shifts.append((s["name"], float(np.interp(BURST_T, t, pts[:, 1]) - (s["f"] - s["f_nom"])), s["lat"], s["lon"]))
+    v = np.array([x[1] for x in shifts])
+    lo, hi = min(shifts, key=lambda x: x[1]), max(shifts, key=lambda x: x[1])
+    out["burst"] = {
+        "utc": dt.datetime.fromtimestamp(p["t_epoch"] + BURST_T, dt.timezone.utc).strftime("%Y-%m-%d %H:%M:%S UTC"),
+        "receivers": len(shifts), "up": int((v > 0).sum()), "down": int((v < 0).sum()),
+        "min_hz": float(v.min()), "max_hz": float(v.max()), "min_name": lo[0], "max_name": hi[0],
+        "lat_range": [min(x[2] for x in shifts), max(x[2] for x in shifts)],
+        "lon_range": [min(x[3] for x in shifts), max(x[3] for x in shifts)],
+    }
+    with open(os.path.join(HERE, "data", "satnogs_20261003.json"), "w") as fh:
+        json.dump(out, fh, indent=1)
+    print(json.dumps({k: v for k, v in out.items() if k != "passes"}, indent=1))
+    for k, q in out["passes"].items():
+        print(k, q["utc"], q["stations"], "t0 rms %.2f s" % q["t0_rms_s"], "v %.3f" % q["v_kms"], "offset sd %.0f Hz" % q["offset_sd_median_hz"])
+
+
+if __name__ == "__main__":
+    main()