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: 04-11 (93), 04-12 (93), 04-13 (93), 04-14 (93), 04-15 (93) — by astronomy; check the weather when the night is within four days.

2031-04-01astronomy score per night — click a bar for that night2031-04-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-04-01 Tue	84	—	unknown	23:30–05:05 (good, 5.58 h)	50.2° 01:10	8.09	68%	63.6°
2031-04-02 Wed	80	—	unknown	02:15–05:00 (good, 2.75 h)	50.2° 01:10	8.04	76%	51.6°
2031-04-03 Thu	54	—	unknown	21:30–05:25 (marginal, 7.92 h)	50.2° 01:05	7.98	84%	39.5°
2031-04-04 Fri	33	—	unknown	22:20–05:10 (marginal, 6.83 h)	50.2° 01:00	7.93	91%	27.3°
2031-04-05 Sat	27	—	unknown	21:35–04:55 (marginal, 7.33 h)	50.2° 00:55	7.87	96%	15.6°
2031-04-06 Sun	24	—	unknown	21:30–04:40 (marginal, 7.17 h)	50.2° 00:50	7.82	99%	8.9°
2031-04-07 Mon	27	—	unknown	21:35–04:30 (marginal, 6.92 h)	50.2° 00:50	7.76	100%	16.7°
2031-04-08 Tue	36	—	unknown	21:35–04:25 (marginal, 6.83 h)	50.2° 00:45	7.7	98%	29.5°
2031-04-09 Wed	86	—	unknown	21:35–22:20 (good, 0.75 h)	50.2° 00:40	7.65	94%	43.2°
2031-04-10 Thu	91	—	unknown	21:35–01:45 (good, 4.17 h)	50.2° 00:35	7.59	87%	57.2°
2031-04-11 Fri	93	—	unknown	21:40–03:30 (good, 5.83 h)	50.2° 00:30	7.53	78%	71.3°
2031-04-12 Sat	93	—	unknown	21:40–04:00 (good, 6.33 h)	50.2° 00:30	7.48	68%	85.4°
2031-04-13 Sun	93	—	unknown	21:40–04:05 (good, 6.42 h)	50.2° 00:25	7.42	57%	99.5°
2031-04-14 Mon	93	—	unknown	21:45–04:05 (good, 6.33 h)	50.2° 00:20	7.36	46%	113.4°
2031-04-15 Tue	93	—	unknown	21:45–04:05 (good, 6.33 h)	50.2° 00:15	7.31	34%	127.2°
2031-04-16 Wed	93	—	unknown	21:45–04:05 (good, 6.33 h)	50.2° 00:10	7.25	24%	140.7°
2031-04-17 Thu	93	—	unknown	21:45–04:00 (good, 6.25 h)	50.2° 00:10	7.19	16%	153.7°
2031-04-18 Fri	93	—	unknown	21:50–03:55 (good, 6.08 h)	50.2° 00:05	7.13	8%	165.6°
2031-04-19 Sat	93	—	unknown	21:50–03:55 (good, 6.08 h)	50.2° 00:00	7.07	4%	170.9°
2031-04-20 Sun	93	—	unknown	21:50–03:50 (good, 6.0 h)	50.2° 23:55	7.02	1%	162.6°
2031-04-21 Mon	93	—	unknown	21:55–03:45 (good, 5.83 h)	50.2° 23:55	6.96	0%	150.8°
2031-04-22 Tue	93	—	unknown	21:55–03:40 (good, 5.75 h)	50.2° 23:50	6.9	2%	138.7°
2031-04-23 Wed	93	—	unknown	21:55–03:35 (good, 5.67 h)	50.2° 23:45	6.84	5%	126.6°
2031-04-24 Thu	93	—	unknown	22:00–03:35 (good, 5.58 h)	50.2° 23:40	6.78	10%	114.6°
2031-04-25 Fri	93	—	unknown	22:00–03:30 (good, 5.5 h)	50.2° 23:35	6.72	16%	102.8°
2031-04-26 Sat	92	—	unknown	22:00–03:25 (good, 5.42 h)	50.2° 23:35	6.67	24%	91.0°
2031-04-27 Sun	89	—	unknown	22:05–03:20 (good, 5.25 h)	50.2° 23:30	6.61	32%	79.3°
2031-04-28 Mon	86	—	unknown	22:05–03:15 (good, 5.17 h)	50.2° 23:25	6.55	42%	67.6°
2031-04-29 Tue	82	—	unknown	22:05–03:15 (good, 5.17 h)	50.2° 23:20	6.49	51%	55.9°
2031-04-30 Wed	65	—	unknown	22:55–02:45 (good, 3.83 h)	50.2° 23:15	6.43	61%	44.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-04-01&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.