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: 04-20 (93), 04-21 (93), 04-22 (93), 04-23 (93), 04-24 (93) — by astronomy; check the weather when the night is within four days.

2030-04-18astronomy score per night — click a bar for that night2030-05-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-04-18 Thu	35	—	unknown	21:50–03:50 (marginal, 6.0 h)	50.2° 00:05	7.12	99%	35.1°
2030-04-19 Fri	83	—	unknown	21:50–22:55 (good, 1.08 h)	50.2° 00:00	7.06	95%	49.7°
2030-04-20 Sat	93	—	unknown	21:50–01:50 (good, 4.0 h)	50.2° 23:55	7.0	89%	64.4°
2030-04-21 Sun	93	—	unknown	21:55–03:15 (good, 5.33 h)	50.2° 23:50	6.94	80%	78.9°
2030-04-22 Mon	93	—	unknown	21:55–03:25 (good, 5.5 h)	50.2° 23:50	6.89	70%	93.1°
2030-04-23 Tue	93	—	unknown	21:55–03:25 (good, 5.5 h)	50.2° 23:45	6.83	59%	106.9°
2030-04-24 Wed	93	—	unknown	22:00–03:30 (good, 5.5 h)	50.2° 23:40	6.77	48%	120.2°
2030-04-25 Thu	93	—	unknown	22:00–03:25 (good, 5.42 h)	50.2° 23:35	6.71	38%	133.1°
2030-04-26 Fri	93	—	unknown	22:00–03:25 (good, 5.42 h)	50.2° 23:30	6.65	28%	145.6°
2030-04-27 Sat	93	—	unknown	22:05–03:20 (good, 5.25 h)	50.2° 23:30	6.59	20%	157.4°
2030-04-28 Sun	93	—	unknown	22:05–03:15 (good, 5.17 h)	50.2° 23:25	6.54	12%	167.4°
2030-04-29 Mon	93	—	unknown	22:05–03:10 (good, 5.08 h)	50.2° 23:20	6.48	7%	169.5°
2030-04-30 Tue	93	—	unknown	22:10–03:10 (good, 5.0 h)	50.2° 23:15	6.42	3%	161.2°
2030-05-01 Wed	93	—	unknown	22:10–03:05 (good, 4.92 h)	50.2° 23:15	6.36	0%	150.4°
2030-05-02 Thu	93	—	unknown	22:10–03:00 (good, 4.83 h)	50.2° 23:10	6.3	0%	139.0°
2030-05-03 Fri	93	—	unknown	22:15–02:55 (good, 4.67 h)	50.2° 23:05	6.25	2%	127.5°
2030-05-04 Sat	93	—	unknown	22:15–02:55 (good, 4.67 h)	50.2° 23:00	6.19	5%	115.9°
2030-05-05 Sun	93	—	unknown	22:15–02:50 (good, 4.58 h)	50.2° 22:55	6.13	10%	104.3°
2030-05-06 Mon	92	—	unknown	22:20–02:45 (good, 4.42 h)	50.2° 22:55	6.07	16%	92.5°
2030-05-07 Tue	89	—	unknown	22:20–02:40 (good, 4.33 h)	50.2° 22:50	6.02	24%	80.7°
2030-05-08 Wed	86	—	unknown	22:20–02:35 (good, 4.25 h)	50.2° 22:45	5.96	32%	68.7°
2030-05-09 Thu	75	—	unknown	22:25–02:35 (good, 4.17 h)	50.2° 22:40	5.9	42%	56.5°
2030-05-10 Fri	58	—	unknown	22:25–02:30 (good, 4.08 h)	50.2° 22:35	5.85	52%	44.0°
2030-05-11 Sat	39	—	unknown	22:25–02:55 (marginal, 4.5 h)	50.2° 22:35	5.79	63%	31.4°
2030-05-12 Sun	29	—	unknown	22:30–02:45 (marginal, 4.25 h)	50.2° 22:30	5.74	73%	19.0°
2030-05-13 Mon	22	—	unknown	22:30–02:30 (marginal, 4.0 h)	50.2° 22:25	5.68	82%	10.0°
2030-05-14 Tue	17	—	unknown	22:30–02:15 (marginal, 3.75 h)	50.2° 22:20	5.63	90%	15.5°
2030-05-15 Wed	16	—	unknown	22:30–02:00 (marginal, 3.5 h)	50.2° 22:15	5.58	96%	28.6°
2030-05-16 Thu	22	—	unknown	22:35–02:05 (marginal, 3.5 h)	50.2° 22:15	5.52	100%	43.1°
2030-05-17 Fri	32	—	unknown	22:35–02:10 (marginal, 3.58 h)	50.2° 22:10	5.47	100%	57.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-04-18&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.