diff --git a/src/app/shared/astro/spectral.spec.ts b/src/app/shared/astro/spectral.spec.ts
index 0300767..acefe11 100644
--- a/src/app/shared/astro/spectral.spec.ts
+++ b/src/app/shared/astro/spectral.spec.ts
@@ -1,6 +1,6 @@
 import { describe, expect, it } from 'vitest';
 
-import { dwarfSequenceAtColor, isGiant, parseSpectralClass, spectralClassification, SPECTRAL_CLASSES, spectralTypeFromColor, spectralTypeToColorIndex, temperatureToColorIndex } from './spectral';
+import { dwarfSequenceAtColor, dwarfSequenceAtTemperature, isGiant, parseSpectralClass, spectralClassification, SPECTRAL_CLASSES, spectralTypeFromColor, spectralTypeToColorIndex, temperatureToColorIndex } from './spectral';
 
 describe('parseSpectralClass', () => {
   it('reads a clean class and subclass', () => {
@@ -180,7 +180,26 @@ describe('dwarfSequenceAtColor', () => {
 
   it('reads the row at the end a colour is past, when asked to', () => {
     expect(dwarfSequenceAtColor(2.2, 'B-V', true)).toEqual({ bMinusV: 2.16, temperatureK: 2420, bolometricCorrectionV: -5.78, gMinusV: -3.09 });
-    expect(dwarfSequenceAtColor(-0.15, 'BP-RP', true)).toEqual({ bMinusV: -0.07, temperatureK: 10700, bolometricCorrectionV: -0.42, gMinusV: 0.018 });
+    expect(dwarfSequenceAtColor(5.3, 'BP-RP', true)).toEqual({ bMinusV: 2.16, temperatureK: 2420, bolometricCorrectionV: -5.78, gMinusV: -3.09 });
+    expect(dwarfSequenceAtColor(-0.4, 'B-V', true)).toEqual({ bMinusV: -0.301, temperatureK: 31400, bolometricCorrectionV: -2.99, gMinusV: null });
     expect(dwarfSequenceAtColor(null, 'B-V', true)).toBeNull();
   });
+
+  it("reads a white dwarf bluer than BP−RP's end at the temperature measured at its colour, and the table's correction there", () => {
+    // Gentile Fusillo et al. (2021): 15 369 K at −0.15, where B9's row had 10 700; between B6 and B5.
+    const point = dwarfSequenceAtColor(-0.15, 'BP-RP', true)!;
+    expect(point.temperatureK).toBeCloseTo(15369, 6);
+    expect(point.bolometricCorrectionV).toBeCloseTo(-1.13 - 0.21 * (869 / 1200), 6);
+    expect(dwarfSequenceAtColor(-0.13, 'BP-RP', true)!.temperatureK).toBeCloseTo(15369 - 4669 * (2 / 3), 6);
+    expect(dwarfSequenceAtColor(-0.6, 'BP-RP', true)!.temperatureK).toBeCloseTo(28585, 6);
+  });
+});
+
+describe('dwarfSequenceAtTemperature', () => {
+  it("is a type's own row at its temperature, between two rows between them, and the end row past either end", () => {
+    expect(dwarfSequenceAtTemperature(5770)).toEqual({ bMinusV: 0.65, temperatureK: 5770, bolometricCorrectionV: -0.085, gMinusV: -0.165 });
+    expect(dwarfSequenceAtTemperature(3615).bolometricCorrectionV).toBeCloseTo(-1.51, 6);
+    expect(dwarfSequenceAtTemperature(50000).temperatureK).toBe(31400);
+    expect(dwarfSequenceAtTemperature(1000).temperatureK).toBe(2420);
+  });
 });
diff --git a/src/app/shared/astro/spectral.ts b/src/app/shared/astro/spectral.ts
index 03579ea..af2a240 100644
--- a/src/app/shared/astro/spectral.ts
+++ b/src/app/shared/astro/spectral.ts
@@ -115,12 +115,7 @@ export function spectralTypeToColorIndex(spectralType: string | null | undefined
  */
 export function temperatureToColorIndex(temperatureK: number): number | null {
   const [hottest, coolest] = [DWARF_SEQUENCE[0], DWARF_SEQUENCE[DWARF_SEQUENCE.length - 1]];
-  if (!(temperatureK <= hottest[3] && temperatureK >= coolest[3])) {
-    return null;
-  }
-  const cooler = Math.max(1, DWARF_SEQUENCE.findIndex((row) => row[3] <= temperatureK));
-  const [hot, cool] = [DWARF_SEQUENCE[cooler - 1], DWARF_SEQUENCE[cooler]];
-  return hot[1] + ((cool[1] - hot[1]) * (hot[3] - temperatureK)) / (hot[3] - cool[3]);
+  return temperatureK <= hottest[3] && temperatureK >= coolest[3] ? dwarfSequenceAtTemperature(temperatureK).bMinusV : null;
 }
 
 /**
@@ -130,7 +125,9 @@ export function temperatureToColorIndex(temperatureK: number): number | null {
  * stops telling types apart — the whole O sequence spans 0.03 of it — to M8.5, past which BP−RP
  * turns back; BP−RP starts at B9, the bluest it is tabulated for, and G−V at B1.5.
  */
-const DWARF_SEQUENCE: readonly (readonly [string, number, number | null, number, number, number | null])[] = [
+type SequenceRow = readonly [string, number, number | null, number, number, number | null];
+
+const DWARF_SEQUENCE: readonly SequenceRow[] = [
   ['B0', -0.301, null, 31400, -2.99, null], ['B0.5', -0.289, null, 29000, -2.83, null], ['B1', -0.278, null, 26000, -2.58, null],
   ['B1.5', -0.252, null, 24500, -2.44, -0.021], ['B2', -0.215, null, 20600, -2.03, -0.008], ['B2.5', -0.198, null, 18500, -1.77, -0.003],
   ['B3', -0.178, null, 17000, -1.54, 0.001], ['B4', -0.165, null, 16400, -1.49, 0.004], ['B5', -0.156, null, 15700, -1.34, 0.007],
@@ -216,7 +213,8 @@ export interface DwarfSequencePoint {
  * same table the spectral estimate reads, so a star's temperature and its estimated type agree.
  * Linear rather than nearest, because the red end is steep: B−V runs 1.495 to 1.53 from M1.5 to
  * M3, over which the temperature drops 190 K and the correction 0.4 magnitudes. `null` outside
- * the table, as for the estimate — or, with `clampToTable`, the row at the end the colour is past.
+ * the table, as for the estimate — or, with `clampToTable`, the row at the end the colour is past,
+ * except bluer than BP−RP's end, where it is read off {@link WHITE_DWARF_BP_RP}.
  */
 export function dwarfSequenceAtColor(colorIndex: number | null, system: 'B-V' | 'BP-RP' = 'B-V', clampToTable = false): DwarfSequencePoint | null {
   const column = system === 'B-V' ? 1 : 2;
@@ -225,15 +223,41 @@ export function dwarfSequenceAtColor(colorIndex: number | null, system: 'B-V' |
   if (colorIndex === null || !Number.isFinite(colorIndex) || (!clampToTable && !(colorIndex >= bluest && colorIndex <= reddest))) {
     return null;
   }
-  const colour = Math.min(Math.max(colorIndex, bluest), reddest);
-  const above = Math.max(1, rows.findIndex((row) => row[column]! >= colour));
-  const [blue, red] = [rows[above - 1], rows[above]];
-  const t = (colour - blue[column]!) / (red[column]! - blue[column]!);
+  if (system === 'BP-RP' && colorIndex < bluest) {
+    const next = Math.max(1, WHITE_DWARF_BP_RP.findIndex(([colour]) => colour >= colorIndex));
+    const [[blueColour, blueK], [redColour, redK]] = [WHITE_DWARF_BP_RP[next - 1], WHITE_DWARF_BP_RP[next]];
+    return dwarfSequenceAtTemperature(blueK + (redK - blueK) * Math.max((colorIndex - blueColour) / (redColour - blueColour), 0));
+  }
+  return sequenceWhere(rows, (row) => row[column]!, Math.min(Math.max(colorIndex, bluest), reddest));
+}
+
+/**
+ * Effective temperature by BP−RP past the blue end of the table, which is B9's −0.12: the median
+ * pure-hydrogen temperature Gentile Fusillo et al. (2021, MNRAS 508, 3877) fit, in bins of ±0.025,
+ * to the 104 of the map's stars there that their white dwarf catalogue has, all white dwarfs; with
+ * the table's end, 10 700 K, and their bluest bin held past it. Every one of them was drawn at B9's
+ * 10 700 K where they measure 14 266 to 39 304, and at a median 1.53 times the radius their mass
+ * and gravity give.
+ */
+const WHITE_DWARF_BP_RP: readonly (readonly [number, number])[] = [
+  [-0.4, 28585], [-0.35, 24521], [-0.3, 22090], [-0.25, 19012], [-0.2, 17079], [-0.15, 15369], [-0.12, 10700]
+];
+
+/** The dwarf sequence at an effective temperature, between the two types it falls between; the end row past either end. */
+export function dwarfSequenceAtTemperature(temperatureK: number): DwarfSequencePoint {
+  return sequenceWhere(ROWS_WITH_COLOUR[1], (row) => -row[3], -temperatureK);
+}
+
+/** The sequence where `key`, rising down `rows`, reaches `value`: linear between the two rows either side, the end row past either end. */
+function sequenceWhere(rows: readonly SequenceRow[], key: (row: SequenceRow) => number, value: number): DwarfSequencePoint {
+  const next = rows.findIndex((row) => key(row) >= value);
+  const [first, second] = next === -1 ? [rows[rows.length - 2], rows[rows.length - 1]] : [rows[Math.max(next, 1) - 1], rows[Math.max(next, 1)]];
+  const t = Math.min(Math.max((value - key(first)) / (key(second) - key(first)), 0), 1);
   const lerp = (from: number, to: number): number => from + (to - from) * t;
   return {
-    bMinusV: lerp(blue[1], red[1]),
-    temperatureK: lerp(blue[3], red[3]),
-    bolometricCorrectionV: lerp(blue[4], red[4]),
-    gMinusV: blue[5] === null || red[5] === null ? null : lerp(blue[5], red[5])
+    bMinusV: lerp(first[1], second[1]),
+    temperatureK: lerp(first[3], second[3]),
+    bolometricCorrectionV: lerp(first[4], second[4]),
+    gMinusV: first[5] === null || second[5] === null ? null : lerp(first[5], second[5])
   };
 }
diff --git a/src/app/shared/astro/stellar.spec.ts b/src/app/shared/astro/stellar.spec.ts
index 8a30ca5..209a541 100644
--- a/src/app/shared/astro/stellar.spec.ts
+++ b/src/app/shared/astro/stellar.spec.ts
@@ -160,9 +160,10 @@ describe('effectiveTemperatureK', () => {
   });
 
   it('reads a colour past the table at its end where there is no type, and the type where there is', () => {
-    // An ultracool dwarf redder than M8.5, a white dwarf bluer than B9, and an O star B−V puts at B0.
+    // An ultracool dwarf redder than M8.5, a white dwarf bluer than B9 at the 19 012 K Gentile
+    // Fusillo et al. (2021) measure at its colour, not B9's 10 700, and an O star B−V puts at B0.
     expect(effectiveTemperatureK({ magnitude: 14.005, distancePc: 4.005, spectralType: 'Unknown', magnitudeBand: 'G', colorIndex: 5.113, colorSystem: 'BP-RP' })).toBe(2420);
-    expect(effectiveTemperatureK({ magnitude: 14, distancePc: 25, spectralType: 'Unknown', magnitudeBand: 'G', colorIndex: -0.25, colorSystem: 'BP-RP' })).toBe(10700);
+    expect(effectiveTemperatureK({ magnitude: 14, distancePc: 25, spectralType: 'Unknown', magnitudeBand: 'G', colorIndex: -0.25, colorSystem: 'BP-RP' })).toBeCloseTo(19012, 6);
     expect(effectiveTemperatureK({ magnitude: 7, distancePc: 121, spectralType: 'O8', colorIndex: -0.31, colorSystem: 'B-V' })).toBe(31400);
     // HD 49748, G5 V at B−V −0.32: the colour is the one that is wrong.
     const g5 = effectiveTemperatureK({ magnitude: 9, distancePc: 184, spectralType: 'G5V', colorIndex: null })!;
@@ -184,6 +185,15 @@ describe('radiusFromLuminositySolar', () => {
     expect(radius / 0.104).toBeLessThan(1.2);
   });
 
+  it('gives a white dwarf bluer than the table the radius its mass and gravity give', () => {
+    // Gaia DR3 6791196382856581376, 24.5 pc: 19 205 K, log g 8.07 and 0.66 M☉ in Gentile Fusillo et
+    // al. (2021), so 0.01245 R☉. At B9's 10 700 K it came out about 1.5 times that.
+    const star = { magnitude: 12.9198, distancePc: 24.5237, spectralType: 'Unknown', magnitudeBand: 'G', colorIndex: -0.2539, colorSystem: 'BP-RP' } as const;
+    const radius = radiusFromLuminositySolar(luminositySolar(star)!, effectiveTemperatureK(star)!);
+    expect(radius / 0.01245).toBeGreaterThan(1 / 1.2);
+    expect(radius / 0.01245).toBeLessThan(1.2);
+  });
+
   it('gives Sirius and TRAPPIST-1 their published radii from colour and brightness alone', () => {
     // 1.711 R☉ (Liebert et al. 2005) and 0.119 R☉ (Agol et al. 2021), each to within a fifth.
     for (const [star, published] of [
diff --git a/src/app/shared/astro/stellar.ts b/src/app/shared/astro/stellar.ts
index 37742c1..0e5f9d9 100644
--- a/src/app/shared/astro/stellar.ts
+++ b/src/app/shared/astro/stellar.ts
@@ -142,13 +142,14 @@ export function luminositySolar(star: StellarPhotometry): number | null {
 }
 
 /**
- * The dwarf sequence at a star's colour — at the end of the table a colour is past, where the star
- * has no type to go by instead. Past the red end are the ultracool dwarfs Gaia measures redder than
- * BP−RP 5.1, M8.5; past the blue end, its white dwarfs and hot stars bluer than −0.12, B9, and
- * B−V's O stars. Unclamped, they had no temperature and were drawn at the Sun's: Gaia DR3
- * 6439125097427143808, an ultracool dwarf 4.0 pc away, and 110 white dwarfs within 50 pc, all at
- * 1 R☉. Beside a type, an off-table colour is more often a bad one than an extreme star — HD
- * 49748, G5 V, at B−V −0.32 — and the type is read instead.
+ * The dwarf sequence at a star's colour — past the table's end, where the star has no type to go
+ * by instead, at the end a colour is past. Past the red end are the ultracool dwarfs Gaia measures
+ * redder than BP−RP 5.1, M8.5, and past B−V's blue end its O stars; Gaia's white dwarfs, bluer
+ * than BP−RP −0.12, are read at the temperature white dwarfs of their colour are measured at.
+ * Unread, they had no temperature and were drawn at the Sun's: Gaia DR3 6439125097427143808, an
+ * ultracool dwarf 4.0 pc away, and 110 white dwarfs within 50 pc, all at 1 R☉. Beside a type, an
+ * off-table colour is more often a bad one than an extreme star — HD 49748, G5 V, at B−V −0.32 —
+ * and the type is read instead.
  */
 function sequenceAtColour(star: StellarPhotometry): DwarfSequencePoint | null {
   if (star.colorIndex == null) {