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: 05-28 (62), 05-27 (61), 05-29 (60), 05-30 (58), 05-31 (56) — by astronomy; check the weather when the night is within four days.

2043-05-27astronomy score per night — click a bar for that night2043-06-25

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-05-27 Wed	61	—	unknown	22:50–01:10 (good, 2.33 h)	50.1° 21:30	5.0	86%	104.9°
2043-05-28 Thu	62	—	unknown	22:50–01:15 (good, 2.42 h)	50.1° 21:30	4.96	78%	117.3°
2043-05-29 Fri	60	—	unknown	22:55–01:15 (good, 2.33 h)	50.1° 21:25	4.92	69%	129.9°
2043-05-30 Sat	58	—	unknown	22:55–01:10 (good, 2.25 h)	50.1° 21:20	4.88	59%	142.8°
2043-05-31 Sun	56	—	unknown	22:55–01:05 (good, 2.17 h)	50.1° 21:15	4.84	49%	155.9°
2043-06-01 Mon	55	—	unknown	22:55–01:05 (good, 2.17 h)	50.1° 21:10	4.8	38%	168.9°
2043-06-02 Tue	52	—	unknown	23:00–01:00 (good, 2.0 h)	50.1° 21:10	4.76	27%	173.8°
2043-06-03 Wed	50	—	unknown	23:00–00:55 (good, 1.92 h)	50.1° 21:05	4.73	17%	160.9°
2043-06-04 Thu	49	—	unknown	23:00–00:50 (good, 1.83 h)	50.1° 21:00	4.7	9%	146.4°
2043-06-05 Fri	47	—	unknown	23:00–00:50 (good, 1.83 h)	50.1° 20:55	4.67	4%	131.5°
2043-06-06 Sat	44	—	unknown	23:05–00:45 (good, 1.67 h)	50.1° 20:50	4.64	1%	116.4°
2043-06-07 Sun	43	—	unknown	23:05–00:40 (good, 1.58 h)	50.1° 20:50	4.61	0%	101.4°
2043-06-08 Mon	41	—	unknown	23:05–00:35 (good, 1.5 h)	50.1° 20:45	4.58	4%	86.6°
2043-06-09 Tue	38	—	unknown	23:05–00:30 (good, 1.42 h)	50.1° 20:40	4.56	9%	72.1°
2043-06-10 Wed	34	—	unknown	23:05–00:30 (good, 1.42 h)	50.1° 20:35	4.54	16%	58.1°
2043-06-11 Thu	28	—	unknown	23:10–00:15 (good, 1.08 h)	50.1° 20:35	4.52	25%	44.6°
2043-06-12 Fri	23	—	unknown	23:10–00:05 (good, 0.92 h)	50.1° 20:30	4.5	35%	31.5°
2043-06-13 Sat	18	—	unknown	23:10–23:50 (good, 0.67 h)	50.1° 20:25	4.48	45%	19.0°
2043-06-14 Sun	15	—	unknown	23:10–00:40 (marginal, 1.5 h)	50.1° 20:20	4.47	55%	7.7°
2043-06-15 Mon	11	—	unknown	23:10–00:30 (marginal, 1.33 h)	50.1° 20:15	4.45	64%	7.8°
2043-06-16 Tue	9	—	unknown	23:10–00:20 (marginal, 1.17 h)	50.1° 20:15	4.44	73%	18.7°
2043-06-17 Wed	7	—	unknown	23:10–00:10 (marginal, 1.0 h)	50.1° 20:10	4.43	81%	30.3°
2043-06-18 Thu	8	—	unknown	23:10–00:05 (marginal, 0.92 h)	50.1° 20:05	4.43	88%	42.0°
2043-06-19 Fri	8	—	unknown	23:10–00:05 (marginal, 0.92 h)	50.1° 20:00	4.42	93%	53.8°
2043-06-20 Sat	9	—	unknown	23:15–00:05 (marginal, 0.83 h)	50.1° 19:55	4.42	97%	65.6°
2043-06-21 Sun	11	—	unknown	23:15–00:10 (marginal, 0.92 h)	50.1° 19:55	4.42	99%	77.6°
2043-06-22 Mon	12	—	unknown	22:20–00:10 (marginal, 1.83 h)	50.1° 19:50	4.42	100%	89.7°
2043-06-23 Tue	13	—	unknown	23:15–23:20 (good, 0.08 h)	50.1° 19:45	4.43	98%	102.0°
2043-06-24 Wed	13	—	unknown	23:15–23:25 (good, 0.17 h)	50.1° 19:40	4.43	94%	114.4°
2043-06-25 Thu	14	—	unknown	23:15–23:30 (good, 0.25 h)	50.1° 19:40	4.44	89%	127.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-05-27&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.