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: 05-24 (69), 05-25 (67), 05-26 (66), 05-27 (64), 05-28 (62) — by astronomy; check the weather when the night is within four days.

2030-05-24astronomy score per night — click a bar for that night2030-06-22

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-05-24 Fri	69	—	unknown	22:45–01:35 (good, 2.83 h)	50.2° 21:40	5.13	43%	154.5°
2030-05-25 Sat	67	—	unknown	22:50–01:30 (good, 2.67 h)	50.2° 21:40	5.08	33%	165.2°
2030-05-26 Sun	66	—	unknown	22:50–01:25 (good, 2.58 h)	50.2° 21:35	5.04	24%	170.2°
2030-05-27 Mon	64	—	unknown	22:50–01:20 (good, 2.5 h)	50.2° 21:30	4.99	16%	163.6°
2030-05-28 Tue	62	—	unknown	22:50–01:20 (good, 2.5 h)	50.2° 21:25	4.95	10%	153.1°
2030-05-29 Wed	60	—	unknown	22:55–01:15 (good, 2.33 h)	50.2° 21:20	4.91	5%	141.8°
2030-05-30 Thu	58	—	unknown	22:55–01:10 (good, 2.25 h)	50.2° 21:20	4.87	2%	130.4°
2030-05-31 Fri	56	—	unknown	22:55–01:05 (good, 2.17 h)	50.2° 21:15	4.83	0%	118.8°
2030-06-01 Sat	53	—	unknown	23:00–01:05 (good, 2.08 h)	50.2° 21:10	4.79	0%	107.2°
2030-06-02 Sun	51	—	unknown	23:00–01:00 (good, 2.0 h)	50.2° 21:05	4.76	2%	95.4°
2030-06-03 Mon	50	—	unknown	23:00–00:55 (good, 1.92 h)	50.2° 21:05	4.73	6%	83.6°
2030-06-04 Tue	48	—	unknown	23:00–00:50 (good, 1.83 h)	50.2° 21:00	4.69	12%	71.6°
2030-06-05 Wed	43	—	unknown	23:00–00:45 (good, 1.75 h)	50.2° 20:55	4.66	19%	59.5°
2030-06-06 Thu	36	—	unknown	23:05–00:45 (good, 1.67 h)	50.2° 20:50	4.63	28%	47.3°
2030-06-07 Fri	29	—	unknown	23:05–00:25 (good, 1.33 h)	50.2° 20:45	4.61	37%	35.0°
2030-06-08 Sat	23	—	unknown	23:05–00:10 (good, 1.08 h)	50.2° 20:45	4.58	48%	22.8°
2030-06-09 Sun	18	—	unknown	23:05–01:00 (marginal, 1.92 h)	50.2° 20:40	4.56	58%	12.1°
2030-06-10 Mon	14	—	unknown	23:05–00:50 (marginal, 1.75 h)	50.2° 20:35	4.53	69%	11.8°
2030-06-11 Tue	10	—	unknown	23:10–00:35 (marginal, 1.42 h)	50.2° 20:30	4.51	79%	23.1°
2030-06-12 Wed	9	—	unknown	23:10–00:25 (marginal, 1.25 h)	50.2° 20:25	4.5	88%	36.8°
2030-06-13 Thu	10	—	unknown	23:10–00:25 (marginal, 1.25 h)	50.2° 20:25	4.48	95%	51.3°
2030-06-14 Fri	12	—	unknown	23:10–00:30 (marginal, 1.33 h)	50.2° 20:20	4.46	99%	66.2°
2030-06-15 Sat	15	—	unknown	23:10–00:30 (marginal, 1.33 h)	50.2° 20:15	4.45	100%	81.1°
2030-06-16 Sun	18	—	unknown	23:10–23:40 (good, 0.5 h)	50.2° 20:10	4.44	98%	95.9°
2030-06-17 Mon	21	—	unknown	23:10–23:45 (good, 0.58 h)	50.2° 20:10	4.43	93%	110.4°
2030-06-18 Tue	24	—	unknown	23:10–23:50 (good, 0.67 h)	50.2° 20:05	4.43	86%	124.4°
2030-06-19 Wed	24	—	unknown	23:10–23:45 (good, 0.58 h)	50.2° 20:00	4.42	78%	137.9°
2030-06-20 Thu	22	—	unknown	23:15–23:50 (good, 0.58 h)	50.2° 19:55	4.42	68%	150.7°
2030-06-21 Fri	20	—	unknown	23:15–23:45 (good, 0.5 h)	50.2° 19:50	4.42	58%	162.3°
2030-06-22 Sat	19	—	unknown	23:15–23:40 (good, 0.42 h)	50.2° 19:50	4.42	48%	170.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-05-24&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.