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: 05-20 (57), 06-01 (50), 06-02 (50), 05-31 (49), 06-03 (49) — by astronomy; check the weather when the night is within four days.

2037-05-20astronomy score per night — click a bar for that night2037-06-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-05-20 Wed	57	—	unknown	22:40–01:50 (good, 3.17 h)	50.2° 21:55	5.3	34%	54.7°
2037-05-21 Thu	44	—	unknown	22:40–01:25 (good, 2.75 h)	50.2° 21:55	5.25	45%	40.6°
2037-05-22 Fri	31	—	unknown	22:45–02:10 (marginal, 3.42 h)	50.2° 21:50	5.21	56%	26.5°
2037-05-23 Sat	22	—	unknown	22:45–02:00 (marginal, 3.25 h)	50.2° 21:45	5.16	68%	12.2°
2037-05-24 Sun	16	—	unknown	22:45–01:45 (marginal, 3.0 h)	50.2° 21:40	5.11	78%	2.1°
2037-05-25 Mon	12	—	unknown	22:50–01:25 (marginal, 2.58 h)	50.1° 21:35	5.07	87%	16.4°
2037-05-26 Tue	11	—	unknown	22:50–01:10 (marginal, 2.33 h)	50.2° 21:35	5.02	93%	30.6°
2037-05-27 Wed	15	—	unknown	22:50–01:15 (marginal, 2.42 h)	50.2° 21:30	4.98	98%	44.7°
2037-05-28 Thu	20	—	unknown	22:55–01:25 (marginal, 2.5 h)	50.2° 21:25	4.94	100%	58.6°
2037-05-29 Fri	27	—	unknown	22:55–23:15 (good, 0.33 h)	50.2° 21:20	4.9	99%	72.2°
2037-05-30 Sat	35	—	unknown	22:55–00:35 (good, 1.67 h)	50.1° 21:20	4.86	96%	85.5°
2037-05-31 Sun	49	—	unknown	22:55–00:45 (good, 1.83 h)	50.2° 21:15	4.82	92%	98.5°
2037-06-01 Mon	50	—	unknown	23:00–00:50 (good, 1.83 h)	50.2° 21:10	4.78	85%	111.2°
2037-06-02 Tue	50	—	unknown	23:00–00:50 (good, 1.83 h)	50.2° 21:05	4.75	77%	123.5°
2037-06-03 Wed	49	—	unknown	23:00–00:55 (good, 1.92 h)	50.2° 21:00	4.72	69%	135.7°
2037-06-04 Thu	48	—	unknown	23:00–00:50 (good, 1.83 h)	50.2° 21:00	4.68	60%	147.6°
2037-06-05 Fri	45	—	unknown	23:05–00:45 (good, 1.67 h)	50.2° 20:55	4.65	50%	159.5°
2037-06-06 Sat	44	—	unknown	23:05–00:40 (good, 1.58 h)	50.2° 20:50	4.62	41%	171.4°
2037-06-07 Sun	42	—	unknown	23:05–00:40 (good, 1.58 h)	50.2° 20:45	4.6	32%	176.7°
2037-06-08 Mon	40	—	unknown	23:05–00:35 (good, 1.5 h)	50.1° 20:40	4.57	23%	164.6°
2037-06-09 Tue	39	—	unknown	23:05–00:30 (good, 1.42 h)	50.2° 20:40	4.55	15%	152.3°
2037-06-10 Wed	38	—	unknown	23:05–00:25 (good, 1.33 h)	50.2° 20:35	4.53	9%	139.7°
2037-06-11 Thu	35	—	unknown	23:10–00:20 (good, 1.17 h)	50.2° 20:30	4.51	4%	126.9°
2037-06-12 Fri	33	—	unknown	23:10–00:20 (good, 1.17 h)	50.2° 20:25	4.49	1%	113.6°
2037-06-13 Sat	33	—	unknown	23:10–00:15 (good, 1.08 h)	50.1° 20:25	4.47	0%	100.1°
2037-06-14 Sun	30	—	unknown	23:10–00:10 (good, 1.0 h)	50.2° 20:20	4.46	2%	86.3°
2037-06-15 Mon	29	—	unknown	23:10–00:05 (good, 0.92 h)	50.2° 20:15	4.45	6%	72.3°
2037-06-16 Tue	26	—	unknown	23:10–00:05 (good, 0.92 h)	50.2° 20:10	4.44	13%	58.1°
2037-06-17 Wed	22	—	unknown	23:10–23:50 (good, 0.67 h)	50.2° 20:05	4.43	21%	43.9°
2037-06-18 Thu	18	—	unknown	23:10–23:40 (good, 0.5 h)	50.1° 20:05	4.43	32%	29.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-05-20&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.