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: 04-02 (93), 04-03 (93), 04-04 (93), 04-05 (93), 04-19 (93) — by astronomy; check the weather when the night is within four days.

2041-04-02astronomy score per night — click a bar for that night2041-05-01

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-04-02 Tue	93	—	unknown	21:25–04:55 (good, 7.5 h)	50.1° 01:05	8.01	5%	147.2°
2041-04-03 Wed	93	—	unknown	21:30–04:55 (good, 7.42 h)	50.1° 01:00	7.95	10%	133.4°
2041-04-04 Thu	93	—	unknown	21:30–04:50 (good, 7.33 h)	50.1° 01:00	7.9	18%	120.1°
2041-04-05 Fri	93	—	unknown	21:30–04:45 (good, 7.25 h)	50.1° 00:55	7.84	26%	107.1°
2041-04-06 Sat	91	—	unknown	21:30–04:40 (good, 7.17 h)	50.1° 00:50	7.78	36%	94.6°
2041-04-07 Sun	87	—	unknown	21:35–04:40 (good, 7.08 h)	50.1° 00:45	7.73	46%	82.3°
2041-04-08 Mon	82	—	unknown	21:45–04:35 (good, 6.83 h)	50.1° 00:40	7.67	55%	70.3°
2041-04-09 Tue	66	—	unknown	23:30–04:10 (good, 4.67 h)	50.1° 00:40	7.62	64%	58.4°
2041-04-10 Wed	56	—	unknown	21:40–04:55 (marginal, 7.25 h)	50.1° 00:35	7.56	73%	46.6°
2041-04-11 Thu	38	—	unknown	21:40–04:40 (marginal, 7.0 h)	50.1° 00:30	7.5	81%	34.8°
2041-04-12 Fri	27	—	unknown	21:50–04:30 (marginal, 6.67 h)	50.1° 00:25	7.44	88%	22.9°
2041-04-13 Sat	22	—	unknown	23:40–04:15 (marginal, 4.58 h)	50.1° 00:25	7.39	94%	10.9°
2041-04-14 Sun	19	—	unknown	00:40–04:00 (marginal, 3.33 h)	50.1° 00:20	7.33	98%	2.1°
2041-04-15 Mon	21	—	unknown	21:45–03:45 (marginal, 6.0 h)	50.1° 00:15	7.27	100%	14.0°
2041-04-16 Tue	26	—	unknown	21:45–03:40 (marginal, 5.92 h)	50.1° 00:10	7.21	100%	26.7°
2041-04-17 Wed	41	—	unknown	21:50–03:55 (marginal, 6.08 h)	50.1° 00:05	7.16	98%	39.6°
2041-04-18 Thu	90	—	unknown	21:50–23:50 (good, 2.0 h)	50.1° 00:05	7.1	94%	52.7°
2041-04-19 Fri	93	—	unknown	21:50–02:15 (good, 4.42 h)	50.1° 00:00	7.04	88%	66.0°
2041-04-20 Sat	93	—	unknown	21:55–03:20 (good, 5.42 h)	50.1° 23:55	6.98	79%	79.5°
2041-04-21 Sun	93	—	unknown	21:55–03:30 (good, 5.58 h)	50.1° 23:50	6.92	70%	93.2°
2041-04-22 Mon	93	—	unknown	21:55–03:30 (good, 5.58 h)	50.1° 23:45	6.87	59%	107.1°
2041-04-23 Tue	93	—	unknown	21:55–03:35 (good, 5.67 h)	50.1° 23:45	6.81	48%	121.2°
2041-04-24 Wed	93	—	unknown	22:00–03:30 (good, 5.5 h)	50.1° 23:40	6.75	36%	135.4°
2041-04-25 Thu	93	—	unknown	22:00–03:25 (good, 5.42 h)	50.1° 23:35	6.69	26%	149.7°
2041-04-26 Fri	93	—	unknown	22:00–03:25 (good, 5.42 h)	50.1° 23:30	6.63	16%	164.0°
2041-04-27 Sat	93	—	unknown	22:05–03:20 (good, 5.25 h)	50.1° 23:25	6.57	8%	177.9°
2041-04-28 Sun	93	—	unknown	22:05–03:15 (good, 5.17 h)	50.1° 23:25	6.52	3%	167.1°
2041-04-29 Mon	93	—	unknown	22:05–03:10 (good, 5.08 h)	50.1° 23:20	6.46	0%	153.0°
2041-04-30 Tue	93	—	unknown	22:10–03:05 (good, 4.92 h)	50.1° 23:15	6.4	0%	139.1°
2041-05-01 Wed	93	—	unknown	22:10–03:05 (good, 4.92 h)	50.1° 23:10	6.34	2%	125.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-04-02&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.