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: 09-12 (100), 09-13 (100), 09-14 (100), 09-15 (100), 09-16 (100) — by astronomy; check the weather when the night is within four days.

2031-08-18astronomy score per night — click a bar for that night2031-09-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-08-18 Mon	68	—	unknown	02:15–04:50 (good, 2.58 h)	72.5° 07:20	6.8	1%	94.7°
2031-08-19 Tue	71	—	unknown	02:10–04:55 (good, 2.75 h)	72.5° 07:15	6.86	3%	107.0°
2031-08-20 Wed	74	—	unknown	02:05–04:55 (good, 2.83 h)	72.5° 07:10	6.92	7%	119.4°
2031-08-21 Thu	76	—	unknown	02:00–04:55 (good, 2.92 h)	72.5° 07:10	6.98	14%	132.0°
2031-08-22 Fri	80	—	unknown	02:00–05:00 (good, 3.0 h)	72.5° 07:05	7.03	21%	144.7°
2031-08-23 Sat	82	—	unknown	01:55–05:00 (good, 3.08 h)	72.5° 07:00	7.09	30%	157.7°
2031-08-24 Sun	84	—	unknown	01:50–05:00 (good, 3.17 h)	72.5° 06:55	7.15	41%	170.3°
2031-08-25 Mon	87	—	unknown	01:45–05:00 (good, 3.25 h)	72.5° 06:50	7.2	52%	173.0°
2031-08-26 Tue	89	—	unknown	01:45–05:05 (good, 3.33 h)	72.5° 06:50	7.26	63%	160.2°
2031-08-27 Wed	91	—	unknown	01:45–05:05 (good, 3.33 h)	72.5° 06:45	7.32	74%	146.2°
2031-08-28 Thu	91	—	unknown	01:40–05:05 (good, 3.42 h)	72.5° 06:40	7.37	83%	131.7°
2031-08-29 Fri	90	—	unknown	01:40–05:10 (good, 3.5 h)	72.5° 06:35	7.43	91%	117.0°
2031-08-30 Sat	69	—	unknown	01:50–05:10 (good, 3.33 h)	72.5° 06:35	7.49	97%	102.2°
2031-08-31 Sun	53	—	unknown	02:45–05:10 (good, 2.42 h)	72.5° 06:30	7.54	100%	87.4°
2031-09-01 Mon	39	—	unknown	04:15–05:10 (good, 0.92 h)	72.5° 06:25	7.6	99%	72.8°
2031-09-02 Tue	28	—	unknown	01:15–05:15 (marginal, 4.0 h)	72.5° 06:20	7.66	97%	58.5°
2031-09-03 Wed	20	—	unknown	01:20–05:15 (marginal, 3.92 h)	72.5° 06:15	7.71	92%	44.6°
2031-09-04 Thu	16	—	unknown	01:20–05:15 (marginal, 3.92 h)	72.5° 06:15	7.77	84%	31.1°
2031-09-05 Fri	21	—	unknown	01:00–05:15 (marginal, 4.25 h)	72.5° 06:10	7.82	76%	18.3°
2031-09-06 Sat	31	—	unknown	00:40–05:20 (marginal, 4.67 h)	72.5° 06:05	7.88	67%	6.9°
2031-09-07 Sun	43	—	unknown	00:30–05:20 (marginal, 4.83 h)	72.5° 06:00	7.93	57%	8.9°
2031-09-08 Mon	57	—	unknown	01:15–05:20 (good, 4.08 h)	72.5° 05:55	7.99	48%	20.1°
2031-09-09 Tue	73	—	unknown	00:50–05:20 (good, 4.5 h)	72.5° 05:55	8.04	38%	31.9°
2031-09-10 Wed	86	—	unknown	00:45–05:25 (good, 4.67 h)	72.5° 05:50	8.09	29%	43.6°
2031-09-11 Thu	93	—	unknown	00:40–05:25 (good, 4.75 h)	72.5° 05:45	8.15	21%	55.3°
2031-09-12 Fri	100	—	unknown	00:35–05:25 (good, 4.83 h)	72.5° 05:40	8.2	14%	67.2°
2031-09-13 Sat	100	—	unknown	00:30–05:25 (good, 4.92 h)	72.5° 05:40	8.26	8%	79.1°
2031-09-14 Sun	100	—	unknown	00:30–05:30 (good, 5.0 h)	72.5° 05:35	8.31	4%	91.2°
2031-09-15 Mon	100	—	unknown	00:25–05:30 (good, 5.08 h)	72.5° 05:30	8.36	1%	103.5°
2031-09-16 Tue	100	—	unknown	00:20–05:30 (good, 5.17 h)	72.5° 05:25	8.41	0%	116.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-08-18&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.