NGC 7331's second bright supernova in just over a year. The ATLAS survey found SN 2026aaiv on September 1, 2026, at about magnitude 17. It is a Type Ia: a white dwarf that drew matter from a companion star until it exploded. Within two weeks it had brightened to about magnitude 12, near its peak, bright enough to see in a 6-inch telescope. It sits about 20″ east and 20″ south of the galaxy's core.

The first, SN 2025rbs, was also a Type Ia. It appeared near the core in July 2025 and also peaked at about magnitude 11.5.

NGC 7331 is a spiral galaxy in Pegasus, about 45 million light-years away. This image was shot over two nights, September 18 and 22, 2026, while the supernova was still near its brightest.

• Supernova: SN 2026aaiv, Type Ia, discovered 2026-09-01 by ATLAS — TNS
• Optics: Celestron EdgeHD 9.25 (C925)
• Camera: ZWO ASI2600MM Pro (mono), −10 °C, gain 100
• Mount: iOptron CEM120EC2
• Filters: Chroma LRGB
• Exposure: 120 × 75 s, 30 each of L, R, G and B (2 h 30 min)
• Captured: 2026-09-18 (R, G) and 2026-09-22 (L, G, B)
• Processing: PixInsight (2× drizzle, SPCC colour calibration), Adobe Photoshop