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 Seven Sisters: 01-10 (100), 01-11 (100), 01-12 (100), 01-13 (100), 01-14 (100) — by astronomy; check the weather when the night is within four days.

2031-01-07astronomy score per night — click a bar for that night2031-02-05

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-01-07 Tue	31	—	unknown	18:50–23:05 (marginal, 4.25 h)	72.5° 21:00	11.38	99%	39.2°
2031-01-08 Wed	48	—	unknown	18:50–01:45 (marginal, 6.92 h)	72.5° 20:55	11.36	100%	51.1°
2031-01-09 Thu	69	—	unknown	18:50–20:40 (good, 1.83 h)	72.5° 20:55	11.34	99%	63.1°
2031-01-10 Fri	100	—	unknown	18:50–23:15 (good, 4.42 h)	72.5° 20:50	11.33	96%	75.2°
2031-01-11 Sat	100	—	unknown	18:50–00:40 (good, 5.83 h)	72.5° 20:45	11.31	91%	87.4°
2031-01-12 Sun	100	—	unknown	18:55–01:30 (good, 6.58 h)	72.5° 20:40	11.29	84%	99.9°
2031-01-13 Mon	100	—	unknown	18:55–01:35 (good, 6.67 h)	72.5° 20:35	11.27	76%	112.5°
2031-01-14 Tue	100	—	unknown	18:55–01:35 (good, 6.67 h)	72.5° 20:35	11.25	67%	125.4°
2031-01-15 Wed	100	—	unknown	18:55–01:35 (good, 6.67 h)	72.5° 20:30	11.23	56%	138.5°
2031-01-16 Thu	100	—	unknown	18:55–01:35 (good, 6.67 h)	72.5° 20:25	11.21	46%	151.9°
2031-01-17 Fri	100	—	unknown	19:00–01:30 (good, 6.5 h)	72.5° 20:20	11.19	35%	165.6°
2031-01-18 Sat	100	—	unknown	19:00–01:30 (good, 6.5 h)	72.5° 20:15	11.16	24%	176.4°
2031-01-19 Sun	100	—	unknown	19:00–01:25 (good, 6.42 h)	72.5° 20:15	11.14	15%	164.7°
2031-01-20 Mon	100	—	unknown	19:00–01:20 (good, 6.33 h)	72.5° 20:10	11.11	7%	150.0°
2031-01-21 Tue	100	—	unknown	19:00–01:15 (good, 6.25 h)	72.5° 20:05	11.09	2%	135.0°
2031-01-22 Wed	100	—	unknown	19:05–01:15 (good, 6.17 h)	72.5° 20:00	11.06	0%	120.0°
2031-01-23 Thu	100	—	unknown	19:05–01:10 (good, 6.08 h)	72.5° 20:00	11.03	1%	105.2°
2031-01-24 Fri	100	—	unknown	19:05–01:05 (good, 6.0 h)	72.5° 19:55	11.01	4%	90.6°
2031-01-25 Sat	100	—	unknown	19:05–01:00 (good, 5.92 h)	72.5° 19:50	10.98	10%	76.4°
2031-01-26 Sun	100	—	unknown	19:05–00:55 (good, 5.83 h)	72.5° 19:45	10.95	18%	62.7°
2031-01-27 Mon	92	—	unknown	19:10–00:55 (good, 5.75 h)	72.5° 19:40	10.92	27%	49.4°
2031-01-28 Tue	84	—	unknown	19:10–00:50 (good, 5.67 h)	72.5° 19:40	10.89	36%	36.6°
2031-01-29 Wed	71	—	unknown	19:10–00:25 (good, 5.25 h)	72.5° 19:35	10.86	46%	24.2°
2031-01-30 Thu	55	—	unknown	20:55–22:35 (good, 1.67 h)	72.5° 19:30	10.83	56%	12.3°
2031-01-31 Fri	40	—	unknown	19:15–00:55 (marginal, 5.67 h)	72.5° 19:25	10.8	65%	3.6°
2031-02-01 Sat	28	—	unknown	19:15–00:40 (marginal, 5.42 h)	72.5° 19:20	10.76	74%	12.6°
2031-02-02 Sun	20	—	unknown	19:15–00:20 (marginal, 5.08 h)	72.5° 19:20	10.73	82%	24.1°
2031-02-03 Mon	20	—	unknown	19:15–00:05 (marginal, 4.83 h)	72.5° 19:15	10.7	88%	35.9°
2031-02-04 Tue	26	—	unknown	19:15–00:05 (marginal, 4.83 h)	72.5° 19:10	10.66	94%	47.8°
2031-02-05 Wed	35	—	unknown	19:20–00:10 (marginal, 4.83 h)	72.5° 19:05	10.63	97%	59.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-01-07&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.