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: 04-18 (93), 04-19 (93), 04-20 (93), 04-21 (93), 04-22 (93) — by astronomy; check the weather when the night is within four days.

2047-04-18astronomy score per night — click a bar for that night2047-05-17

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2047-04-18 Thu	93	—	unknown	21:50–03:55 (good, 6.08 h)	50.1° 00:05	7.12	32%	133.3°
2047-04-19 Fri	93	—	unknown	21:50–03:55 (good, 6.08 h)	50.1° 00:00	7.07	23%	145.2°
2047-04-20 Sat	93	—	unknown	21:50–03:50 (good, 6.0 h)	50.1° 23:55	7.01	16%	156.5°
2047-04-21 Sun	93	—	unknown	21:55–03:45 (good, 5.83 h)	50.1° 23:55	6.95	10%	166.5°
2047-04-22 Mon	93	—	unknown	21:55–03:40 (good, 5.75 h)	50.1° 23:50	6.89	5%	170.1°
2047-04-23 Tue	93	—	unknown	21:55–03:35 (good, 5.67 h)	50.1° 23:45	6.83	2%	162.9°
2047-04-24 Wed	93	—	unknown	22:00–03:35 (good, 5.58 h)	50.1° 23:40	6.78	0%	152.4°
2047-04-25 Thu	93	—	unknown	22:00–03:30 (good, 5.5 h)	50.1° 23:35	6.72	1%	141.1°
2047-04-26 Fri	93	—	unknown	22:00–03:25 (good, 5.42 h)	50.1° 23:35	6.66	3%	129.6°
2047-04-27 Sat	93	—	unknown	22:05–03:20 (good, 5.25 h)	50.1° 23:30	6.6	7%	117.9°
2047-04-28 Sun	93	—	unknown	22:05–03:15 (good, 5.17 h)	50.1° 23:25	6.54	12%	106.0°
2047-04-29 Mon	91	—	unknown	22:05–03:15 (good, 5.17 h)	50.1° 23:20	6.48	19%	94.0°
2047-04-30 Tue	88	—	unknown	22:10–03:10 (good, 5.0 h)	50.1° 23:20	6.43	28%	81.7°
2047-05-01 Wed	85	—	unknown	22:10–03:05 (good, 4.92 h)	50.1° 23:15	6.37	37%	69.2°
2047-05-02 Thu	81	—	unknown	22:10–03:00 (good, 4.83 h)	50.1° 23:10	6.31	48%	56.4°
2047-05-03 Fri	55	—	unknown	22:35–02:35 (good, 4.0 h)	50.1° 23:05	6.25	58%	43.3°
2047-05-04 Sat	37	—	unknown	22:15–03:20 (marginal, 5.08 h)	50.1° 23:00	6.19	69%	30.1°
2047-05-05 Sun	29	—	unknown	22:15–03:10 (marginal, 4.92 h)	50.1° 23:00	6.14	79%	17.3°
2047-05-06 Mon	22	—	unknown	22:20–02:55 (marginal, 4.58 h)	50.1° 22:55	6.08	88%	9.7°
2047-05-07 Tue	18	—	unknown	22:20–02:40 (marginal, 4.33 h)	50.1° 22:50	6.02	95%	18.1°
2047-05-08 Wed	20	—	unknown	22:20–02:30 (marginal, 4.17 h)	50.1° 22:45	5.97	99%	31.9°
2047-05-09 Thu	31	—	unknown	22:25–02:40 (marginal, 4.25 h)	50.1° 22:40	5.91	100%	46.5°
2047-05-10 Fri	46	—	unknown	22:25–23:40 (good, 1.25 h)	50.1° 22:40	5.85	98%	61.2°
2047-05-11 Sat	78	—	unknown	22:25–01:25 (good, 3.0 h)	50.1° 22:35	5.8	93%	75.8°
2047-05-12 Sun	85	—	unknown	22:25–02:00 (good, 3.58 h)	50.1° 22:30	5.74	86%	90.0°
2047-05-13 Mon	88	—	unknown	22:30–02:05 (good, 3.58 h)	50.1° 22:25	5.69	78%	103.7°
2047-05-14 Tue	90	—	unknown	22:30–02:10 (good, 3.67 h)	50.1° 22:25	5.64	68%	116.9°
2047-05-15 Wed	88	—	unknown	22:30–02:05 (good, 3.58 h)	50.1° 22:20	5.58	58%	129.7°
2047-05-16 Thu	86	—	unknown	22:35–02:05 (good, 3.5 h)	50.1° 22:15	5.53	48%	141.9°
2047-05-17 Fri	84	—	unknown	22:35–02:05 (good, 3.5 h)	50.1° 22:10	5.48	38%	153.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2047-04-18&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.