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: 05-16 (86), 05-17 (84), 05-18 (81), 05-19 (75), 05-20 (68) — by astronomy; check the weather when the night is within four days.

2045-05-16astronomy score per night — click a bar for that night2045-06-14

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-05-16 Tue	86	—	unknown	22:35–02:05 (good, 3.5 h)	50.1° 22:15	5.5	0%	126.5°
2045-05-17 Wed	84	—	unknown	22:35–02:00 (good, 3.42 h)	50.1° 22:10	5.45	2%	112.6°
2045-05-18 Thu	81	—	unknown	22:40–01:55 (good, 3.25 h)	50.1° 22:05	5.4	6%	98.4°
2045-05-19 Fri	75	—	unknown	22:40–01:55 (good, 3.25 h)	50.1° 22:00	5.35	13%	84.2°
2045-05-20 Sat	68	—	unknown	22:40–01:50 (good, 3.17 h)	50.1° 21:55	5.3	22%	69.9°
2045-05-21 Sun	57	—	unknown	22:45–01:45 (good, 3.0 h)	50.1° 21:55	5.25	32%	55.7°
2045-05-22 Mon	45	—	unknown	22:45–01:25 (good, 2.67 h)	50.1° 21:50	5.2	43%	41.7°
2045-05-23 Tue	32	—	unknown	22:45–02:05 (marginal, 3.33 h)	50.1° 21:45	5.16	55%	28.0°
2045-05-24 Wed	25	—	unknown	22:45–01:55 (marginal, 3.17 h)	50.1° 21:40	5.11	66%	15.2°
2045-05-25 Thu	19	—	unknown	22:50–01:45 (marginal, 2.92 h)	50.1° 21:35	5.06	76%	8.0°
2045-05-26 Fri	15	—	unknown	22:50–01:35 (marginal, 2.75 h)	50.1° 21:35	5.02	84%	16.3°
2045-05-27 Sat	13	—	unknown	22:50–01:20 (marginal, 2.5 h)	50.1° 21:30	4.98	91%	28.7°
2045-05-28 Sun	15	—	unknown	22:55–01:20 (marginal, 2.42 h)	50.1° 21:25	4.93	96%	41.5°
2045-05-29 Mon	20	—	unknown	22:55–01:25 (marginal, 2.5 h)	50.1° 21:20	4.89	99%	54.2°
2045-05-30 Tue	25	—	unknown	22:55–23:00 (good, 0.08 h)	50.1° 21:20	4.86	100%	66.8°
2045-05-31 Wed	32	—	unknown	22:55–00:10 (good, 1.25 h)	50.1° 21:15	4.82	98%	79.2°
2045-06-01 Thu	37	—	unknown	23:00–00:40 (good, 1.67 h)	50.1° 21:10	4.78	95%	91.4°
2045-06-02 Fri	47	—	unknown	23:00–00:45 (good, 1.75 h)	50.1° 21:05	4.75	90%	103.4°
2045-06-03 Sat	48	—	unknown	23:00–00:45 (good, 1.75 h)	50.1° 21:00	4.71	84%	115.2°
2045-06-04 Sun	48	—	unknown	23:00–00:45 (good, 1.75 h)	50.1° 21:00	4.68	76%	127.0°
2045-06-05 Mon	45	—	unknown	23:05–00:45 (good, 1.67 h)	50.1° 20:55	4.65	68%	138.6°
2045-06-06 Tue	44	—	unknown	23:05–00:40 (good, 1.58 h)	50.1° 20:50	4.62	59%	150.1°
2045-06-07 Wed	42	—	unknown	23:05–00:40 (good, 1.58 h)	50.1° 20:45	4.6	49%	161.3°
2045-06-08 Thu	40	—	unknown	23:05–00:35 (good, 1.5 h)	50.1° 20:40	4.57	40%	170.7°
2045-06-09 Fri	39	—	unknown	23:05–00:30 (good, 1.42 h)	50.1° 20:40	4.55	30%	168.8°
2045-06-10 Sat	38	—	unknown	23:05–00:25 (good, 1.33 h)	50.1° 20:35	4.53	21%	157.9°
2045-06-11 Sun	35	—	unknown	23:10–00:20 (good, 1.17 h)	50.1° 20:30	4.51	13%	145.3°
2045-06-12 Mon	33	—	unknown	23:10–00:20 (good, 1.17 h)	50.1° 20:25	4.49	7%	132.0°
2045-06-13 Tue	33	—	unknown	23:10–00:15 (good, 1.08 h)	50.1° 20:25	4.47	2%	118.1°
2045-06-14 Wed	30	—	unknown	23:10–00:10 (good, 1.0 h)	50.1° 20:20	4.46	0%	103.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-05-16&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.