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: 05-11 (93), 05-12 (93), 05-13 (92), 05-14 (91), 05-15 (89) — by astronomy; check the weather when the night is within four days.

2031-05-11astronomy score per night — click a bar for that night2031-06-09

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-05-11 Sun	93	—	unknown	22:25–02:15 (good, 3.83 h)	50.2° 22:35	5.81	71%	109.9°
2031-05-12 Mon	93	—	unknown	22:25–02:15 (good, 3.83 h)	50.2° 22:30	5.75	60%	123.9°
2031-05-13 Tue	92	—	unknown	22:30–02:15 (good, 3.75 h)	50.2° 22:25	5.7	48%	137.6°
2031-05-14 Wed	91	—	unknown	22:30–02:15 (good, 3.75 h)	50.2° 22:20	5.64	38%	150.8°
2031-05-15 Thu	89	—	unknown	22:30–02:10 (good, 3.67 h)	50.2° 22:20	5.59	27%	163.0°
2031-05-16 Fri	86	—	unknown	22:35–02:05 (good, 3.5 h)	50.2° 22:15	5.54	18%	171.0°
2031-05-17 Sat	85	—	unknown	22:35–02:05 (good, 3.5 h)	50.2° 22:10	5.48	11%	165.4°
2031-05-18 Sun	83	—	unknown	22:35–02:00 (good, 3.42 h)	50.2° 22:05	5.43	6%	154.2°
2031-05-19 Mon	80	—	unknown	22:40–01:55 (good, 3.25 h)	50.2° 22:05	5.38	2%	142.2°
2031-05-20 Tue	78	—	unknown	22:40–01:50 (good, 3.17 h)	50.2° 22:00	5.33	0%	130.2°
2031-05-21 Wed	77	—	unknown	22:40–01:45 (good, 3.08 h)	50.2° 21:55	5.28	0%	118.2°
2031-05-22 Thu	74	—	unknown	22:45–01:45 (good, 3.0 h)	50.2° 21:50	5.23	2%	106.3°
2031-05-23 Fri	72	—	unknown	22:45–01:40 (good, 2.92 h)	50.2° 21:45	5.18	6%	94.6°
2031-05-24 Sat	69	—	unknown	22:45–01:35 (good, 2.83 h)	50.2° 21:45	5.14	12%	82.9°
2031-05-25 Sun	63	—	unknown	22:50–01:30 (good, 2.67 h)	50.2° 21:40	5.09	18%	71.2°
2031-05-26 Mon	57	—	unknown	22:50–01:25 (good, 2.58 h)	50.2° 21:35	5.05	26%	59.5°
2031-05-27 Tue	48	—	unknown	22:50–01:25 (good, 2.58 h)	50.2° 21:30	5.0	35%	47.8°
2031-05-28 Wed	38	—	unknown	22:50–01:00 (good, 2.17 h)	50.2° 21:25	4.96	45%	36.0°
2031-05-29 Thu	28	—	unknown	22:55–00:05 (good, 1.17 h)	50.2° 21:25	4.92	55%	24.3°
2031-05-30 Fri	22	—	unknown	22:55–01:35 (marginal, 2.67 h)	50.2° 21:20	4.88	65%	13.4°
2031-05-31 Sat	17	—	unknown	22:55–01:25 (marginal, 2.5 h)	50.2° 21:15	4.84	74%	9.5°
2031-06-01 Sun	13	—	unknown	22:55–01:10 (marginal, 2.25 h)	50.2° 21:10	4.8	83%	18.8°
2031-06-02 Mon	11	—	unknown	23:00–01:00 (marginal, 2.0 h)	50.2° 21:10	4.77	91%	31.8°
2031-06-03 Tue	13	—	unknown	23:00–01:00 (marginal, 2.0 h)	50.2° 21:05	4.73	96%	45.8°
2031-06-04 Wed	17	—	unknown	23:00–01:05 (marginal, 2.08 h)	50.2° 21:00	4.7	100%	60.3°
2031-06-05 Thu	22	—	unknown	23:00–23:10 (good, 0.17 h)	50.2° 20:55	4.67	100%	75.1°
2031-06-06 Fri	27	—	unknown	23:05–00:15 (good, 1.17 h)	50.2° 20:50	4.64	97%	90.1°
2031-06-07 Sat	33	—	unknown	23:05–00:25 (good, 1.33 h)	50.2° 20:50	4.61	91%	104.9°
2031-06-08 Sun	40	—	unknown	23:05–00:30 (good, 1.42 h)	50.2° 20:45	4.59	83%	119.6°
2031-06-09 Mon	39	—	unknown	23:05–00:25 (good, 1.33 h)	50.2° 20:40	4.56	74%	133.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-05-11&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.