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: 04-30 (93), 05-01 (93), 05-02 (93), 05-03 (93), 05-04 (93) — by astronomy; check the weather when the night is within four days.

2030-04-30astronomy score per night — click a bar for that night2030-05-29

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2030-05-18 Sat	45	—	unknown	22:35–00:20 (good, 1.75 h)	50.2° 22:05	5.42	97%	72.9°
2030-05-19 Sun	67	—	unknown	22:40–01:25 (good, 2.75 h)	50.2° 22:00	5.37	91%	87.6°
2030-05-20 Mon	73	—	unknown	22:40–01:35 (good, 2.92 h)	50.2° 22:00	5.32	83%	102.0°
2030-05-21 Tue	75	—	unknown	22:40–01:40 (good, 3.0 h)	50.2° 21:55	5.27	74%	116.0°
2030-05-22 Wed	73	—	unknown	22:45–01:35 (good, 2.83 h)	50.2° 21:50	5.22	64%	129.4°
2030-05-23 Thu	71	—	unknown	22:45–01:40 (good, 2.92 h)	50.2° 21:45	5.17	53%	142.3°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-04-30&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.