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 Seven Sisters: 01-19 (100), 01-20 (100), 01-21 (100), 01-22 (100), 02-03 (100) — by astronomy; check the weather when the night is within four days.

2026-01-19astronomy score per night — click a bar for that night2026-02-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2026-01-19 Mon	100	93	93	19:00–01:15 (good, 6.25 h)	72.5° 20:10	11.13	1%	107.1°
2026-01-20 Tue	100	64	64	19:00–23:00 (good, 4.0 h)	72.5° 20:10	11.11	5%	94.3°
2026-01-21 Wed	100	0	0	—	72.5° 20:05	11.08	10%	81.3°
2026-01-22 Thu	100	0	0	—	72.5° 20:00	11.06	17%	68.0°
2026-01-23 Fri	96	43	41	19:05–21:00 (good, 1.92 h)	72.5° 19:55	11.03	26%	54.6°
2026-01-24 Sat	87	6	5	20:00–21:00 (marginal, 1.0 h)	72.5° 19:55	11.0	36%	41.0°
2026-01-25 Sun	71	0	0	—	72.5° 19:50	10.97	47%	27.1°
2026-01-26 Mon	55	0	0	—	72.5° 19:45	10.94	58%	13.1°
2026-01-27 Tue	36	11	4	—	72.5° 19:40	10.91	69%	1.6°
2026-01-28 Wed	23	0	0	—	72.5° 19:35	10.88	80%	15.7°
2026-01-29 Thu	16	0	0	—	72.5° 19:35	10.85	88%	30.2°
2026-01-30 Fri	23	0	0	—	72.5° 19:30	10.82	95%	44.7°
2026-01-31 Sat	36	0	0	—	72.5° 19:25	10.79	99%	59.2°
2026-02-01 Sun	54	0	0	—	72.5° 19:20	10.76	100%	73.4°
2026-02-02 Mon	74	0	0	—	72.5° 19:15	10.72	99%	87.4°
2026-02-03 Tue	100	7	7	18:45–19:00 (marginal, 0.25 h)	72.5° 19:15	10.69	95%	101.1°
2026-02-04 Wed	100	0	0	—	72.5° 19:10	10.66	89%	114.4°
2026-02-05 Thu	100	0	0	—	72.5° 19:05	10.62	82%	127.3°
2026-02-06 Fri	100	0	0	—	72.5° 19:00	10.59	74%	139.8°
2026-02-07 Sat	100	81	81	19:20–23:00 (good, 3.67 h)	72.5° 19:00	10.55	65%	152.0°
2026-02-08 Sun	100	37	37	19:20–20:00 (good, 0.67 h)	72.5° 18:55	10.51	56%	164.0°
2026-02-09 Mon	100	0	0	—	72.5° 18:50	10.48	46%	175.8°
2026-02-10 Tue	100	0	0	—	72.5° 18:45	10.44	37%	172.2°
2026-02-11 Wed	100	0	0	—	72.5° 18:40	10.4	28%	160.4°
2026-02-12 Thu	100	0	0	—	72.5° 18:40	10.36	20%	148.4°
2026-02-13 Fri	100	0	0	—	72.5° 18:35	10.32	13%	136.3°
2026-02-14 Sat	100	16	16	23:00–00:00 (marginal, 1.0 h)	72.5° 18:30	10.29	7%	123.9°
2026-02-15 Sun	100	0	0	—	72.5° 18:25	10.25	3%	111.3°
2026-02-16 Mon	100	13	13	19:30–20:00 (good, 0.5 h)	72.5° 18:20	10.21	0%	98.3°
2026-02-17 Tue	100	0	0	—	72.5° 18:20	10.17	0%	85.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-01-19&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.