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: 11-14 (11), 11-13 (8), 11-12 (6), 11-11 (4), 11-10 (3) — by astronomy; check the weather when the night is within four days.

2028-10-16astronomy score per night — click a bar for that night2028-11-14

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-10-16 Mon	0	—	unknown	—	50.2° 12:10	9.89	2%	9.8°
2028-10-17 Tue	0	—	unknown	—	50.2° 12:05	9.93	0%	19.0°
2028-10-18 Wed	0	—	unknown	—	50.2° 12:00	9.97	1%	32.7°
2028-10-19 Thu	0	—	unknown	—	50.2° 11:55	10.01	5%	46.9°
2028-10-20 Fri	0	—	unknown	—	50.2° 11:50	10.06	11%	60.9°
2028-10-21 Sat	0	—	unknown	—	50.2° 11:45	10.1	19%	74.5°
2028-10-22 Sun	0	—	unknown	—	50.2° 11:40	10.14	28%	87.7°
2028-10-23 Mon	0	—	unknown	—	50.2° 11:40	10.18	37%	100.4°
2028-10-24 Tue	0	—	unknown	—	50.2° 11:35	10.22	47%	112.8°
2028-10-25 Wed	0	—	unknown	—	50.2° 11:30	10.26	57%	124.8°
2028-10-26 Thu	0	—	unknown	—	50.2° 11:25	10.3	66%	136.5°
2028-10-27 Fri	0	—	unknown	—	50.2° 11:25	10.33	75%	147.9°
2028-10-28 Sat	0	—	unknown	—	50.2° 10:20	10.37	82%	158.8°
2028-10-29 Sun	0	—	unknown	—	50.2° 10:15	10.41	89%	168.0°
2028-10-30 Mon	0	—	unknown	—	50.2° 10:10	10.45	94%	169.2°
2028-10-31 Tue	0	—	unknown	—	50.2° 10:05	10.48	98%	160.7°
2028-11-01 Wed	0	—	unknown	—	50.2° 10:05	10.52	100%	149.6°
2028-11-02 Thu	0	—	unknown	—	50.2° 10:00	10.56	100%	137.9°
2028-11-03 Fri	1	—	unknown	—	50.2° 09:55	10.59	98%	125.7°
2028-11-04 Sat	1	—	unknown	—	50.2° 09:50	10.63	94%	113.3°
2028-11-05 Sun	1	—	unknown	—	50.2° 09:45	10.66	88%	100.7°
2028-11-06 Mon	1	—	unknown	—	50.2° 09:45	10.69	80%	87.8°
2028-11-07 Tue	1	—	unknown	—	50.2° 09:40	10.73	71%	74.8°
2028-11-08 Wed	2	—	unknown	05:25–05:30 (marginal, 0.08 h)	50.2° 09:35	10.76	61%	61.5°
2028-11-09 Thu	2	—	unknown	05:20–05:30 (marginal, 0.17 h)	50.2° 09:30	10.79	50%	48.0°
2028-11-10 Fri	3	—	unknown	05:15–05:35 (marginal, 0.33 h)	50.2° 09:30	10.82	38%	34.5°
2028-11-11 Sat	4	—	unknown	05:10–05:35 (marginal, 0.42 h)	50.2° 09:25	10.86	28%	21.3°
2028-11-12 Sun	6	—	unknown	05:05–05:35 (marginal, 0.5 h)	50.2° 09:20	10.89	18%	10.7°
2028-11-13 Mon	8	—	unknown	05:00–06:10 (marginal, 1.17 h)	50.2° 09:15	10.92	10%	14.1°
2028-11-14 Tue	11	—	unknown	05:25–05:35 (good, 0.17 h)	50.2° 09:10	10.95	4%	26.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-10-16&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.