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Landsat 7 ETM+ — what it added vs. TM?
maybe landsat

Two upgrades over the older TM:

  • 🩶 New panchromatic band — 0.52–0.90 µm at 15 m
    • Enables pan-sharpening (fuse 30 m MS with 15 m pan → 15 m color)
  • 🔥 Thermal improved — 120 m → 60 m
  • Other VSWIR bands unchanged at 30 m
landsat/etm-pan ✎ edit content

Landsat 1–3 orbit — altitude + revisit?
maybe landsat
  • 🛰️ Altitude: 919 km
  • 🧭 Inclination: ~99°, sun-synchronous
  • ⏱️ Period: 103 min → 14 orbits/day
  • 🔁 Revisit: 18 days

⚠️ Orbit was lowered to 705 km at Landsat 4 for better spatial resolution. That’s why later Landsats have 16-day revisit instead of 18.

landsat/l1-3-orbit ✎ edit content

Landsat TM — 7 bands and their resolutions?
essential landsat

TM has 7 spectral bands. All 30 m except thermal at 120 m.

  • 🟦🟩🟥 Visible (30 m)
    • Band 1 · Blue · 0.45–0.52 µm
    • Band 2 · Green · 0.52–0.60 µm
    • Band 3 · Red · 0.63–0.69 µm
  • 🟪 Near-infrared (30 m)
    • Band 4 · NIR · 0.76–0.90 µm
  • 🟫 Shortwave infrared (30 m)
    • Band 5 · SWIR-1 · 1.55–1.75 µm
    • Band 7 · SWIR-2 · 2.08–2.35 µm
  • 🔥 Thermal — coarser: 120 m
    • Band 6 · Thermal IR · 10.4–12.5 µm

⚠️ Numbering oddity: 1-2-3-4-5-7-6. Band 7 was added later and squeezed in spectrally between 5 and 6 but numbered last.

💡

Bands 1-2-3-4-5-7-6. Yes, 7 before 6. All 30 m except thermal band 6 at 120 m. Watch for 'Band 4 = NIR' (on TM) vs 'Band 5 = NIR' (on OLI).

landsat/tm-bands ✎ edit content

Landsat 9 — launch date, altitude, sensors?
essential landsat
  • 🚀 Launch: Sept 27, 2021
  • 🛰️ Orbit
    • Altitude: 705 km
    • Sun-synchronous, 10 AM equator crossing
    • 16-day repeat (8-day combined with Landsat 8)
  • 📷 Sensors (the “-2” matches Landsat-9)
    • OLI-2 — Operational Land Imager: 9 bands, 30 m VSWIR, 15 m pan
    • TIRS-2 — Thermal Infrared Sensor: 2 thermal bands at 100 m
  • 🎚️ Radiometric: 14-bit (vs 12-bit on L8, 8-bit on L5/7)
💡

705 km, 2021. OLI-2 + TIRS-2 (the '-2' matches Landsat-9). With L8 flying opposite, combined revisit ≈ 8 days.

landsat/landsat9-overview ✎ edit content

Radiometric resolution bit depths?
maybe landsat

More bits → finer tonal detail in shadows + highlights.

  • 🎚️ 8-bit — 0–255 (256 levels) — Landsat MSS/TM/ETM+, SPOT
  • 🎚️ 10-bit — 0–1 023
  • 🎚️ 11-bit — 0–2 047 — IKONOS
  • 🎚️ 12-bit — 0–4 095 — Landsat 8 OLI
  • 🎚️ 14-bit — 0–16 383 — Landsat 9 OLI-2
landsat/radiometric-bits ✎ edit content

Landsat WRS-2 — path/row grid specs?
likely landsat
  • 🌐 Grid size: 233 paths × 248 rows covering the globe
  • 🧭 Numbering
    • Paths numbered westward — Path 001 over eastern Greenland & S. America
    • Rows numbered southward from 80°N — Row 60 ≈ equator
  • 🛰️ Versions
    • WRS-2 — Landsat 4–9 (16-day cycle, current)
    • WRS-1 — Landsat 1–3 (251 paths, 18-day cycle, retired)
landsat/wrs2 ✎ edit content

Landsat MSS band numbering — why does it differ across satellites?
maybe landsat

MSS flew on Landsat 1/2 and Landsat 4/5 — but the bands got renumbered. Same wavelengths, new numbers:

  • 🟩 Green (0.5–0.6 µm) — L1/2: B4 → L4/5: B1
  • 🟥 Red (0.6–0.7 µm) — L1/2: B5 → L4/5: B2
  • 🟪 NIR-1 (0.7–0.8 µm) — L1/2: B6 → L4/5: B3
  • 🟪 NIR-2 (0.8–1.1 µm) — L1/2: B7 → L4/5: B4

⚠️ MSS has no blue band — visible spectrum starts at green. That’s why MSS imagery can’t be made into natural-color composites.

landsat/mss-renumbering ✎ edit content