diff --git a/src/app/features/body-detail/body-view-model.spec.ts b/src/app/features/body-detail/body-view-model.spec.ts
index 4d9d47a..b15fa55 100644
--- a/src/app/features/body-detail/body-view-model.spec.ts
+++ b/src/app/features/body-detail/body-view-model.spec.ts
@@ -3,7 +3,7 @@ import { describe, expect, it } from 'vitest';
 import { BodyRecord, OrbitalElements } from '../../shared/models/body.model';
 import { ExoplanetRecord } from '../../shared/models/exoplanet.model';
 import { StarRecord, SUN_STAR_ID } from '../../shared/models/star.model';
-import { buildBodyViewModel, heliocentricPeriodDays, starSurfaceOf } from './body-view-model';
+import { buildBodyViewModel, heliocentricPeriodDays, luminosityOf, starSurfaceOf } from './body-view-model';
 
 const orbit = (overrides: Partial<OrbitalElements> = {}): OrbitalElements => ({
   semiMajorAxisAu: 1,
@@ -123,6 +123,23 @@ describe('buildBodyViewModel', () => {
   });
 });
 
+describe('luminosityOf', () => {
+  // KMT-2016-BLG-1107L as the ETL adds it from the archive: no V, no G, so the stand-in 15.
+  const lens: StarRecord = { id: 1070000536, name: 'KMT-2016-BLG-1107L', x: 6651, y: 0, z: 0, magnitude: 15, spectralType: 'Unknown', colorIndex: null, source: 'exoplanet-archive' };
+  const lensB: ExoplanetRecord = { id: 'lens-b', hostStarId: lens.id, hostStarName: lens.name, name: 'KMT-2016-BLG-1107L b', orbit: { semiMajorAxisAu: 0.342 } };
+
+  it('has none from a magnitude no survey measured, and gives its planets no temperature from it', () => {
+    expect(luminosityOf(lens)).toBeNull();
+    expect(buildBodyViewModel('lens-b', { bodies: [], exoplanets: [lensB], stars: [lens] })?.appearance.equilibriumTemperatureK).toBeNull();
+    // The same figure measured in V is a star, 37 L☉ at that distance.
+    expect(luminosityOf({ ...lens, magnitudeBand: 'V' })).toBeCloseTo(36.8, 0);
+  });
+
+  it('is 1 for the Sun, whatever its magnitude is filed under', () => {
+    expect(luminosityOf(sun)).toBe(1);
+  });
+});
+
 describe('starSurfaceOf', () => {
   // Proxima Centauri as HYG describes it, and one of its planets' archive rows.
   const proxima: StarRecord = { id: 70666, name: 'Proxima Centauri', x: 1.2959, y: 0, z: 0, magnitude: 11.01, magnitudeBand: 'V', spectralType: 'M5Ve', colorIndex: 1.807, colorSystem: 'B-V' };
diff --git a/src/app/features/body-detail/body-view-model.ts b/src/app/features/body-detail/body-view-model.ts
index 1615eb1..f0786e8 100644
--- a/src/app/features/body-detail/body-view-model.ts
+++ b/src/app/features/body-detail/body-view-model.ts
@@ -18,9 +18,14 @@ export interface BodyCatalogues {
  * Bolometric luminosity of a star in solar units, from what the catalogue measured: apparent
  * magnitude in its band, parallax distance, and a bolometric correction read off the colour, or
  * off the spectral type where there is no colour.
+ *
+ * None where no survey measured the star and its magnitude is the ETL's stand-in, which is all
+ * 309 stars without a band have. The 265 archive hosts among them came out at a median 33 L☉
+ * from it, KMT-2016-BLG-1107L, a 0.087 M☉ star, at 37, and OGLE-2005-BLG-390L b, published at
+ * about 50 K, read 388 K. The Sun is the unit, whatever its magnitude is filed under.
  */
 export function luminosityOf(star: StarRecord | undefined): number | null {
-  return star ? luminositySolar(photometryOf(star)) : null;
+  return star && (star.magnitudeBand || star.id === SUN_STAR_ID) ? luminositySolar(photometryOf(star)) : null;
 }
 
 function photometryOf(star: StarRecord): StellarPhotometry {
@@ -60,9 +65,9 @@ export function starSurfaceOf(star: StarRecord, planets: readonly ExoplanetRecor
   if (measured) {
     return { radiusSolar: measured, radiusDerived: false, temperatureK };
   }
-  // Not from the ETL's stand-in magnitude, which is all 309 stars without a band have: PSR
-  // J1719-1438 came out 2.3 solar radii, wider than its planet's orbit.
-  const luminosity = star.magnitudeBand ? luminosityOf(star) : null;
+  // None from a stand-in magnitude: PSR J1719-1438 came out 2.3 solar radii, wider than its
+  // planet's orbit.
+  const luminosity = luminosityOf(star);
   return {
     radiusSolar: luminosity !== null && temperatureK !== null ? radiusFromLuminositySolar(luminosity, temperatureK) : null,
     radiusDerived: true,