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 3C 273: 12-12 (58), 12-11 (57), 12-10 (55), 12-09 (53), 12-08 (52) — by astronomy; check the weather when the night is within four days.

2040-11-13astronomy score per night — click a bar for that night2040-12-12

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-11-13 Tue	9	—	unknown	05:30–05:35 (good, 0.08 h)	50.1° 09:15	10.92	75%	166.0°
2040-11-14 Wed	10	—	unknown	05:25–05:35 (good, 0.17 h)	50.1° 09:10	10.95	84%	179.2°
2040-11-15 Thu	12	—	unknown	05:20–05:40 (good, 0.33 h)	50.1° 09:10	10.98	91%	166.6°
2040-11-16 Fri	13	—	unknown	05:25–05:40 (good, 0.25 h)	50.1° 09:05	11.0	96%	153.2°
2040-11-17 Sat	13	—	unknown	05:25–05:40 (good, 0.25 h)	50.1° 09:00	11.03	99%	140.0°
2040-11-18 Sun	14	—	unknown	05:20–05:40 (good, 0.33 h)	50.1° 08:55	11.06	100%	127.0°
2040-11-19 Mon	14	—	unknown	05:20–05:40 (good, 0.33 h)	50.1° 08:55	11.08	99%	114.3°
2040-11-20 Tue	12	—	unknown	05:30–05:45 (good, 0.25 h)	50.1° 08:50	11.11	95%	101.8°
2040-11-21 Wed	11	—	unknown	04:35–05:45 (marginal, 1.17 h)	50.1° 08:45	11.13	90%	89.6°
2040-11-22 Thu	10	—	unknown	04:35–05:45 (marginal, 1.17 h)	50.1° 08:40	11.16	84%	77.5°
2040-11-23 Fri	9	—	unknown	04:35–05:45 (marginal, 1.17 h)	50.1° 08:35	11.18	76%	65.6°
2040-11-24 Sat	9	—	unknown	04:35–05:45 (marginal, 1.17 h)	50.1° 08:35	11.2	68%	53.7°
2040-11-25 Sun	10	—	unknown	04:25–05:50 (marginal, 1.42 h)	50.1° 08:30	11.23	59%	41.9°
2040-11-26 Mon	12	—	unknown	04:20–05:50 (marginal, 1.5 h)	50.1° 08:25	11.25	50%	30.0°
2040-11-27 Tue	17	—	unknown	05:35–05:50 (good, 0.25 h)	50.1° 08:20	11.27	40%	18.0°
2040-11-28 Wed	22	—	unknown	04:50–05:50 (good, 1.0 h)	50.1° 08:15	11.29	31%	5.7°
2040-11-29 Thu	27	—	unknown	04:40–05:50 (good, 1.17 h)	50.1° 08:15	11.31	22%	7.0°
2040-11-30 Fri	32	—	unknown	04:30–05:50 (good, 1.33 h)	50.1° 08:10	11.32	14%	20.0°
2040-12-01 Sat	37	—	unknown	04:20–05:55 (good, 1.58 h)	50.1° 08:05	11.34	7%	33.4°
2040-12-02 Sun	41	—	unknown	04:15–05:55 (good, 1.67 h)	50.1° 08:00	11.36	2%	47.3°
2040-12-03 Mon	42	—	unknown	04:10–05:55 (good, 1.75 h)	50.1° 08:00	11.37	0%	61.5°
2040-12-04 Tue	44	—	unknown	04:05–05:55 (good, 1.83 h)	50.1° 07:55	11.39	1%	76.0°
2040-12-05 Wed	46	—	unknown	04:05–05:55 (good, 1.83 h)	50.1° 07:50	11.4	4%	90.7°
2040-12-06 Thu	48	—	unknown	04:00–06:00 (good, 2.0 h)	50.1° 07:45	11.42	10%	105.4°
2040-12-07 Fri	50	—	unknown	03:55–06:00 (good, 2.08 h)	50.1° 07:40	11.43	18%	120.1°
2040-12-08 Sat	52	—	unknown	03:50–06:00 (good, 2.17 h)	50.1° 07:40	11.44	27%	134.7°
2040-12-09 Sun	53	—	unknown	03:45–06:00 (good, 2.25 h)	50.1° 07:35	11.45	38%	149.0°
2040-12-10 Mon	55	—	unknown	03:45–06:00 (good, 2.25 h)	50.1° 07:30	11.46	49%	163.0°
2040-12-11 Tue	57	—	unknown	03:40–06:00 (good, 2.33 h)	50.1° 07:25	11.47	60%	176.7°
2040-12-12 Wed	58	—	unknown	03:35–06:00 (good, 2.42 h)	50.1° 07:20	11.48	71%	169.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-11-13&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.