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: 04-05 (93), 04-06 (93), 04-07 (93), 04-08 (93), 04-09 (93) — by astronomy; check the weather when the night is within four days.

2045-04-01astronomy score per night — click a bar for that night2045-04-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-04-01 Sat	26	—	unknown	21:25–04:55 (marginal, 7.5 h)	50.1° 01:10	8.06	100%	12.1°
2045-04-02 Sun	35	—	unknown	21:25–04:50 (marginal, 7.42 h)	50.1° 01:05	8.01	98%	24.4°
2045-04-03 Mon	83	—	unknown	21:30–22:20 (good, 0.83 h)	50.1° 01:00	7.95	94%	37.5°
2045-04-04 Tue	90	—	unknown	21:30–01:15 (good, 3.75 h)	50.1° 01:00	7.89	88%	50.5°
2045-04-05 Wed	93	—	unknown	21:30–03:25 (good, 5.92 h)	50.1° 00:55	7.84	81%	63.2°
2045-04-06 Thu	93	—	unknown	21:30–04:15 (good, 6.75 h)	50.1° 00:50	7.78	72%	75.6°
2045-04-07 Fri	93	—	unknown	21:35–04:20 (good, 6.75 h)	50.1° 00:45	7.73	63%	87.7°
2045-04-08 Sat	93	—	unknown	21:35–04:25 (good, 6.83 h)	50.1° 00:40	7.67	54%	99.5°
2045-04-09 Sun	93	—	unknown	21:35–04:25 (good, 6.83 h)	50.1° 00:40	7.61	44%	111.3°
2045-04-10 Mon	93	—	unknown	21:40–04:25 (good, 6.75 h)	50.1° 00:35	7.56	35%	123.0°
2045-04-11 Tue	93	—	unknown	21:40–04:20 (good, 6.67 h)	50.1° 00:30	7.5	26%	134.7°
2045-04-12 Wed	93	—	unknown	21:40–04:20 (good, 6.67 h)	50.1° 00:25	7.44	18%	146.4°
2045-04-13 Thu	93	—	unknown	21:40–04:15 (good, 6.58 h)	50.1° 00:25	7.39	12%	158.0°
2045-04-14 Fri	93	—	unknown	21:45–04:10 (good, 6.42 h)	50.1° 00:20	7.33	6%	168.7°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-04-01&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.