Rozhen Observation Calendar

Which nights are best for a target over the coming weeks. The astronomy mark (darkness × altitude × Moon) is computed for every night; the weather and the overall mark exist only where Open-Meteo has a forecast (the next four days) or ERA5 history (past nights) — the rest is honestly blank.

Best nights for Andromeda Galaxy: 01-18 (100), 01-19 (100), 01-20 (100), 01-21 (97), 01-22 (92) — by astronomy; check the weather when the night is within four days.

2026-01-18astronomy score per night — click a bar for that night2026-02-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2026-01-18 Sun	100	0	0	—	89.5° 17:15	11.16	0%	89.9°
2026-01-19 Mon	100	92	92	19:00–23:20 (good, 4.33 h)	89.7° 17:10	11.13	1%	78.9°
2026-01-20 Tue	100	83	83	19:00–22:25 (good, 3.42 h)	89.7° 17:05	11.11	5%	67.9°
2026-01-21 Wed	97	0	0	—	89.6° 17:00	11.08	10%	57.1°
2026-01-22 Thu	92	0	0	—	89.5° 16:55	11.06	17%	46.8°
2026-01-23 Fri	79	54	43	19:05–21:00 (good, 1.92 h)	89.6° 16:55	11.03	26%	37.7°
2026-01-24 Sat	61	9	5	—	89.7° 16:50	11.0	36%	31.2°
2026-01-25 Sun	45	0	0	—	89.7° 16:45	10.97	47%	29.5°
2026-01-26 Mon	33	0	0	—	89.6° 16:40	10.94	58%	33.5°
2026-01-27 Tue	26	17	4	—	89.5° 16:40	10.91	69%	41.8°
2026-01-28 Wed	24	0	0	—	89.6° 16:35	10.88	80%	52.4°
2026-01-29 Thu	26	0	0	—	89.7° 16:30	10.85	88%	64.2°
2026-01-30 Fri	33	0	0	—	89.7° 16:25	10.82	95%	76.6°
2026-01-31 Sat	41	0	0	—	89.5° 16:20	10.79	99%	89.2°
2026-02-01 Sun	51	0	0	—	89.5° 16:20	10.76	100%	101.6°
2026-02-02 Mon	61	0	0	—	89.7° 16:15	10.72	99%	113.6°
2026-02-03 Tue	72	10	8	18:45–19:00 (marginal, 0.25 h)	89.7° 16:10	10.69	95%	124.8°
2026-02-04 Wed	73	0	0	—	89.6° 16:05	10.66	89%	135.0°
2026-02-05 Thu	72	0	0	—	89.5° 16:00	10.62	82%	143.4°
2026-02-06 Fri	71	0	0	—	89.6° 16:00	10.59	74%	149.0°
2026-02-07 Sat	68	90	61	19:20–22:00 (good, 2.67 h)	89.7° 15:55	10.55	65%	150.6°
2026-02-08 Sun	66	38	25	19:20–19:45 (good, 0.42 h)	89.7° 15:50	10.51	56%	147.8°
2026-02-09 Mon	63	0	0	—	89.6° 15:45	10.48	46%	141.7°
2026-02-10 Tue	61	0	0	—	89.5° 15:45	10.44	37%	133.7°
2026-02-11 Wed	59	0	0	—	89.6° 15:40	10.4	28%	124.5°
2026-02-12 Thu	57	0	0	—	89.7° 15:35	10.36	20%	114.6°
2026-02-13 Fri	54	0	0	—	89.7° 15:30	10.32	13%	104.3°
2026-02-14 Sat	53	1	0	—	89.5° 15:25	10.29	7%	93.5°
2026-02-15 Sun	50	0	0	—	89.5° 15:25	10.25	3%	82.5°
2026-02-16 Mon	48	23	11	19:30–20:00 (marginal, 0.5 h)	89.7° 15:20	10.21	0%	71.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-01-18&days=30"
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&days=30&format=csv" -o m31-calendar.csv

One row per night: score_astronomy always, score_weather / score only where a forecast or history exists (null otherwise, with weather_source saying which), best window, dark hours, Moon illumination and separation, transit. 7–60 nights. Errors: 400 with invalid_date or target_unresolved. Results are cached for six hours; calculation version 2026-10-10.1.