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: 01-07 (100), 01-08 (100), 01-09 (100), 01-10 (100), 01-11 (100) — by astronomy; check the weather when the night is within four days.

2040-01-07astronomy score per night — click a bar for that night2040-02-05

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-01-07 Sat	100	—	unknown	18:50–02:10 (good, 7.33 h)	72.5° 21:00	11.38	45%	142.5°
2040-01-08 Sun	100	—	unknown	18:50–02:10 (good, 7.33 h)	72.5° 21:00	11.36	34%	155.9°
2040-01-09 Mon	100	—	unknown	18:50–02:05 (good, 7.25 h)	72.5° 20:55	11.35	24%	169.2°
2040-01-10 Tue	100	—	unknown	18:50–02:00 (good, 7.17 h)	72.5° 20:50	11.33	15%	172.7°
2040-01-11 Wed	100	—	unknown	18:50–01:55 (good, 7.08 h)	72.5° 20:45	11.31	7%	159.3°
2040-01-12 Thu	100	—	unknown	18:55–01:55 (good, 7.0 h)	72.5° 20:40	11.29	2%	144.5°
2040-01-13 Fri	100	—	unknown	18:55–01:50 (good, 6.92 h)	72.5° 20:40	11.27	0%	129.4°
2040-01-14 Sat	100	—	unknown	18:55–01:45 (good, 6.83 h)	72.5° 20:35	11.25	1%	114.4°
2040-01-15 Sun	100	—	unknown	18:55–01:40 (good, 6.75 h)	72.5° 20:30	11.23	5%	99.6°
2040-01-16 Mon	100	—	unknown	18:55–01:35 (good, 6.67 h)	72.5° 20:25	11.21	11%	85.1°
2040-01-17 Tue	100	—	unknown	19:00–01:35 (good, 6.58 h)	72.5° 20:25	11.19	19%	71.1°
2040-01-18 Wed	99	—	unknown	19:00–01:30 (good, 6.5 h)	72.5° 20:20	11.17	28%	57.6°
2040-01-19 Thu	90	—	unknown	19:00–01:25 (good, 6.42 h)	72.5° 20:15	11.14	38%	44.6°
2040-01-20 Fri	82	—	unknown	19:00–01:20 (good, 6.33 h)	72.5° 20:10	11.12	48%	32.0°
2040-01-21 Sat	62	—	unknown	21:15–00:00 (good, 2.75 h)	72.5° 20:05	11.09	58%	19.9°
2040-01-22 Sun	45	—	unknown	19:05–01:35 (marginal, 6.5 h)	72.5° 20:05	11.07	68%	8.8°
2040-01-23 Mon	31	—	unknown	19:05–01:20 (marginal, 6.25 h)	72.5° 20:00	11.04	76%	7.0°
2040-01-24 Tue	22	—	unknown	19:05–01:00 (marginal, 5.92 h)	72.5° 19:55	11.01	84%	17.4°
2040-01-25 Wed	18	—	unknown	19:05–21:15 (marginal, 2.17 h)	72.5° 19:50	10.98	90%	28.9°
2040-01-26 Thu	23	—	unknown	19:05–23:00 (marginal, 3.92 h)	72.5° 19:45	10.96	95%	40.6°
2040-01-27 Fri	32	—	unknown	19:10–00:30 (marginal, 5.33 h)	72.5° 19:45	10.93	98%	52.4°
2040-01-28 Sat	46	—	unknown	19:10–19:15 (good, 0.08 h)	72.5° 19:40	10.9	100%	64.3°
2040-01-29 Sun	63	—	unknown	19:10–21:45 (good, 2.58 h)	72.5° 19:35	10.87	100%	76.4°
2040-01-30 Mon	80	—	unknown	19:10–23:10 (good, 4.0 h)	72.5° 19:30	10.83	97%	88.7°
2040-01-31 Tue	100	—	unknown	19:15–00:15 (good, 5.0 h)	72.5° 19:30	10.8	93%	101.1°
2040-02-01 Wed	100	—	unknown	19:15–00:20 (good, 5.08 h)	72.5° 19:25	10.77	88%	113.6°
2040-02-02 Thu	100	—	unknown	19:15–00:20 (good, 5.08 h)	72.5° 19:20	10.74	80%	126.4°
2040-02-03 Fri	100	—	unknown	19:15–00:20 (good, 5.08 h)	72.5° 19:15	10.7	71%	139.3°
2040-02-04 Sat	100	—	unknown	19:15–00:20 (good, 5.08 h)	72.5° 19:10	10.67	61%	152.5°
2040-02-05 Sun	100	—	unknown	19:20–00:20 (good, 5.0 h)	72.5° 19:10	10.64	50%	165.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-01-07&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.