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: 07-13 (2), 07-14 (2), 07-15 (1), 07-16 (1), 07-17 (1) — by astronomy; check the weather when the night is within four days.

2031-07-13astronomy score per night — click a bar for that night2031-08-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-07-13 Sun	2	—	unknown	22:15–22:20 (marginal, 0.08 h)	50.2° 18:25	4.91	26%	136.0°
2031-07-14 Mon	2	—	unknown	22:10–22:15 (marginal, 0.08 h)	50.2° 18:25	4.95	18%	124.0°
2031-07-15 Tue	1	—	unknown	—	50.2° 18:20	4.99	12%	112.2°
2031-07-16 Wed	1	—	unknown	—	50.2° 18:15	5.03	6%	100.5°
2031-07-17 Thu	1	—	unknown	—	50.2° 18:10	5.08	2%	88.8°
2031-07-18 Fri	1	—	unknown	—	50.2° 18:05	5.12	0%	77.1°
2031-07-19 Sat	1	—	unknown	—	50.2° 18:05	5.17	0%	65.4°
2031-07-20 Sun	1	—	unknown	—	50.2° 18:00	5.21	2%	53.7°
2031-07-21 Mon	1	—	unknown	—	50.2° 17:55	5.26	5%	42.0°
2031-07-22 Tue	0	—	unknown	—	50.2° 17:50	5.31	10%	30.3°
2031-07-23 Wed	0	—	unknown	—	50.2° 17:45	5.36	17%	18.9°
2031-07-24 Thu	0	—	unknown	—	50.2° 17:45	5.41	25%	9.7°
2031-07-25 Fri	0	—	unknown	—	50.2° 17:40	5.46	34%	11.9°
2031-07-26 Sat	0	—	unknown	—	50.2° 17:35	5.51	45%	22.8°
2031-07-27 Sun	0	—	unknown	—	50.2° 17:30	5.57	55%	35.5°
2031-07-28 Mon	0	—	unknown	—	50.2° 17:30	5.62	66%	48.9°
2031-07-29 Tue	0	—	unknown	—	50.2° 17:25	5.67	77%	62.8°
2031-07-30 Wed	0	—	unknown	—	50.2° 17:20	5.73	86%	77.2°
2031-07-31 Thu	0	—	unknown	—	50.2° 17:15	5.78	93%	92.0°
2031-08-01 Fri	0	—	unknown	—	50.2° 17:10	5.84	98%	106.9°
2031-08-02 Sat	0	—	unknown	—	50.2° 17:10	5.89	100%	121.9°
2031-08-03 Sun	0	—	unknown	—	50.2° 17:05	5.95	99%	136.7°
2031-08-04 Mon	0	—	unknown	—	50.2° 17:00	6.0	95%	151.0°
2031-08-05 Tue	0	—	unknown	—	50.2° 16:55	6.06	88%	164.2°
2031-08-06 Wed	0	—	unknown	—	50.2° 16:50	6.12	80%	171.4°
2031-08-07 Thu	0	—	unknown	—	50.2° 16:50	6.17	71%	163.5°
2031-08-08 Fri	0	—	unknown	—	50.2° 16:45	6.23	61%	151.6°
2031-08-09 Sat	0	—	unknown	—	50.2° 16:40	6.29	51%	139.4°
2031-08-10 Sun	0	—	unknown	—	50.2° 16:35	6.34	41%	127.3°
2031-08-11 Mon	0	—	unknown	—	50.2° 16:30	6.4	32%	115.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-07-13&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.