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: 01-05 (100), 01-06 (100), 01-07 (100), 01-08 (100), 01-09 (100) — by astronomy; check the weather when the night is within four days.

2026-01-05astronomy score per night — click a bar for that night2026-02-03

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2026-01-05 Mon	100	6	6	—	72.5° 21:05	11.4	92%	79.5°
2026-01-06 Tue	100	0	0	—	72.5° 21:05	11.39	84%	93.3°
2026-01-07 Wed	100	0	0	—	72.5° 21:00	11.37	76%	106.6°
2026-01-08 Thu	100	53	53	23:00–01:55 (good, 2.92 h)	72.5° 20:55	11.36	67%	119.4°
2026-01-09 Fri	100	44	44	21:00–23:05 (good, 2.08 h)	72.5° 20:50	11.34	57%	131.9°
2026-01-10 Sat	100	36	36	21:00–23:00 (good, 2.0 h)	72.5° 20:50	11.32	47%	144.1°
2026-01-11 Sun	100	0	0	—	72.5° 20:45	11.31	38%	156.1°
2026-01-12 Mon	100	97	97	19:00–01:50 (good, 6.83 h)	72.5° 20:40	11.29	29%	167.9°
2026-01-13 Tue	100	12	12	23:00–00:00 (marginal, 1.0 h)	72.5° 20:35	11.27	21%	179.0°
2026-01-14 Wed	100	99	99	18:55–01:45 (good, 6.83 h)	72.5° 20:30	11.25	14%	168.4°
2026-01-15 Thu	100	88	88	18:55–23:00 (good, 4.08 h)	72.5° 20:30	11.23	8%	156.5°
2026-01-16 Fri	100	0	0	—	72.5° 20:25	11.2	4%	144.4°
2026-01-17 Sat	100	77	77	19:00–00:00 (good, 5.0 h)	72.5° 20:20	11.18	1%	132.2°
2026-01-18 Sun	100	0	0	—	72.5° 20:15	11.16	0%	119.8°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2026-01-05&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.