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: 04-27 (93), 04-28 (93), 04-29 (93), 04-30 (93), 05-01 (93) — by astronomy; check the weather when the night is within four days.

2043-04-23astronomy score per night — click a bar for that night2043-05-22

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-04-23 Thu	23	—	unknown	21:55–03:20 (marginal, 5.42 h)	50.1° 23:45	6.84	100%	24.6°
2043-04-24 Fri	32	—	unknown	22:00–03:25 (marginal, 5.42 h)	50.1° 23:40	6.78	100%	36.3°
2043-04-25 Sat	48	—	unknown	22:00–03:35 (marginal, 5.58 h)	50.1° 23:35	6.72	98%	48.0°
2043-04-26 Sun	91	—	unknown	22:00–00:45 (good, 2.75 h)	50.1° 23:35	6.66	94%	59.8°
2043-04-27 Mon	93	—	unknown	22:05–02:20 (good, 4.25 h)	50.1° 23:30	6.6	88%	71.7°
2043-04-28 Tue	93	—	unknown	22:05–02:55 (good, 4.83 h)	50.1° 23:25	6.54	82%	83.6°
2043-04-29 Wed	93	—	unknown	22:05–03:00 (good, 4.92 h)	50.1° 23:20	6.49	74%	95.7°
2043-04-30 Thu	93	—	unknown	22:10–03:00 (good, 4.83 h)	50.1° 23:20	6.43	64%	108.0°
2043-05-01 Fri	93	—	unknown	22:10–03:00 (good, 4.83 h)	50.1° 23:15	6.37	55%	120.5°
2043-05-02 Sat	93	—	unknown	22:10–03:00 (good, 4.83 h)	50.1° 23:10	6.31	44%	133.3°
2043-05-03 Sun	93	—	unknown	22:15–03:00 (good, 4.75 h)	50.1° 23:05	6.25	34%	146.6°
2043-05-04 Mon	93	—	unknown	22:15–02:55 (good, 4.67 h)	50.1° 23:00	6.2	24%	160.1°
2043-05-05 Tue	93	—	unknown	22:15–02:50 (good, 4.58 h)	50.1° 23:00	6.14	15%	173.2°
2043-05-06 Wed	93	—	unknown	22:15–02:45 (good, 4.5 h)	50.1° 22:55	6.08	7%	169.4°
2043-05-07 Thu	93	—	unknown	22:20–02:40 (good, 4.33 h)	50.1° 22:50	6.03	2%	155.0°
2043-05-08 Fri	93	—	unknown	22:20–02:40 (good, 4.33 h)	50.1° 22:45	5.97	0%	139.9°
2043-05-09 Sat	93	—	unknown	22:20–02:35 (good, 4.25 h)	50.1° 22:40	5.91	1%	124.7°
2043-05-10 Sun	93	—	unknown	22:25–02:30 (good, 4.08 h)	50.1° 22:40	5.86	5%	109.7°
2043-05-11 Mon	91	—	unknown	22:25–02:25 (good, 4.0 h)	50.1° 22:35	5.8	12%	94.9°
2043-05-12 Tue	86	—	unknown	22:25–02:20 (good, 3.92 h)	50.1° 22:30	5.75	20%	80.6°
2043-05-13 Wed	74	—	unknown	22:30–02:20 (good, 3.83 h)	50.1° 22:25	5.69	30%	66.6°
2043-05-14 Thu	61	—	unknown	22:30–02:00 (good, 3.5 h)	50.1° 22:25	5.64	40%	53.2°
2043-05-15 Fri	45	—	unknown	22:30–01:45 (good, 3.25 h)	50.1° 22:20	5.58	50%	40.2°
2043-05-16 Sat	33	—	unknown	22:35–02:35 (marginal, 4.0 h)	50.1° 22:15	5.53	61%	27.6°
2043-05-17 Sun	25	—	unknown	22:35–02:25 (marginal, 3.83 h)	50.1° 22:10	5.48	70%	15.6°
2043-05-18 Mon	20	—	unknown	22:35–02:10 (marginal, 3.58 h)	50.1° 22:05	5.43	79%	5.3°
2043-05-19 Tue	16	—	unknown	22:40–02:00 (marginal, 3.33 h)	50.1° 22:05	5.38	86%	10.4°
2043-05-20 Wed	14	—	unknown	22:40–01:50 (marginal, 3.17 h)	50.1° 22:00	5.33	92%	21.7°
2043-05-21 Thu	15	—	unknown	22:40–01:40 (marginal, 3.0 h)	50.1° 21:55	5.28	96%	33.3°
2043-05-22 Fri	20	—	unknown	22:45–01:45 (marginal, 3.0 h)	50.1° 21:50	5.23	99%	45.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-04-23&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.