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: 04-15 (93), 04-16 (93), 04-17 (93), 04-18 (93), 04-19 (93) — by astronomy; check the weather when the night is within four days.

2045-04-15astronomy score per night — click a bar for that night2045-05-14

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-04-15 Sat	93	—	unknown	21:45–04:05 (good, 6.33 h)	50.1° 00:15	7.27	2%	171.1°
2045-04-16 Sun	93	—	unknown	21:45–04:00 (good, 6.25 h)	50.1° 00:10	7.21	0%	161.0°
2045-04-17 Mon	93	—	unknown	21:50–04:00 (good, 6.17 h)	50.1° 00:05	7.15	1%	148.5°
2045-04-18 Tue	93	—	unknown	21:50–03:55 (good, 6.08 h)	50.1° 00:05	7.1	3%	135.4°
2045-04-19 Wed	93	—	unknown	21:50–03:50 (good, 6.0 h)	50.1° 00:00	7.04	8%	121.9°
2045-04-20 Thu	93	—	unknown	21:55–03:45 (good, 5.83 h)	50.1° 23:55	6.98	15%	108.2°
2045-04-21 Fri	91	—	unknown	21:55–03:45 (good, 5.83 h)	50.1° 23:50	6.92	24%	94.4°
2045-04-22 Sat	86	—	unknown	21:55–03:40 (good, 5.75 h)	50.1° 23:45	6.86	35%	80.5°
2045-04-23 Sun	82	—	unknown	21:55–03:35 (good, 5.67 h)	50.1° 23:45	6.81	46%	66.5°
2045-04-24 Mon	67	—	unknown	22:10–03:10 (good, 5.0 h)	50.1° 23:40	6.75	57%	52.5°
2045-04-25 Tue	47	—	unknown	22:00–03:55 (marginal, 5.92 h)	50.1° 23:35	6.69	68%	38.6°
2045-04-26 Wed	33	—	unknown	22:00–03:45 (marginal, 5.75 h)	50.1° 23:30	6.63	78%	24.9°
2045-04-27 Thu	25	—	unknown	22:05–03:30 (marginal, 5.42 h)	50.1° 23:30	6.57	87%	12.4°
2045-04-28 Fri	21	—	unknown	22:05–03:20 (marginal, 5.25 h)	50.1° 23:25	6.51	94%	8.9°
2045-04-29 Sat	20	—	unknown	22:05–03:05 (marginal, 5.0 h)	50.1° 23:20	6.46	98%	19.6°
2045-04-30 Sun	24	—	unknown	22:10–03:00 (marginal, 4.83 h)	50.1° 23:15	6.4	100%	32.5°
2045-05-01 Mon	37	—	unknown	22:10–03:10 (marginal, 5.0 h)	50.1° 23:10	6.34	99%	45.5°
2045-05-02 Tue	76	—	unknown	22:10–00:00 (good, 1.83 h)	50.1° 23:10	6.28	97%	58.4°
2045-05-03 Wed	90	—	unknown	22:15–01:35 (good, 3.33 h)	50.1° 23:05	6.22	92%	70.9°
2045-05-04 Thu	93	—	unknown	22:15–02:25 (good, 4.17 h)	50.1° 23:00	6.17	86%	83.3°
2045-05-05 Fri	93	—	unknown	22:15–02:30 (good, 4.25 h)	50.1° 22:55	6.11	78%	95.4°
2045-05-06 Sat	93	—	unknown	22:20–02:35 (good, 4.25 h)	50.1° 22:50	6.05	70%	107.3°
2045-05-07 Sun	93	—	unknown	22:20–02:35 (good, 4.25 h)	50.1° 22:50	6.0	61%	119.0°
2045-05-08 Mon	93	—	unknown	22:20–02:35 (good, 4.25 h)	50.1° 22:45	5.94	52%	130.7°
2045-05-09 Tue	93	—	unknown	22:25–02:30 (good, 4.08 h)	50.1° 22:40	5.88	42%	142.4°
2045-05-10 Wed	93	—	unknown	22:25–02:30 (good, 4.08 h)	50.1° 22:35	5.83	33%	154.0°
2045-05-11 Thu	93	—	unknown	22:25–02:25 (good, 4.0 h)	50.1° 22:35	5.77	24%	165.1°
2045-05-12 Fri	93	—	unknown	22:30–02:20 (good, 3.83 h)	50.1° 22:30	5.72	16%	172.2°
2045-05-13 Sat	92	—	unknown	22:30–02:15 (good, 3.75 h)	50.1° 22:25	5.66	10%	165.2°
2045-05-14 Sun	90	—	unknown	22:30–02:10 (good, 3.67 h)	50.1° 22:20	5.61	4%	153.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-04-15&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.