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: 09-11 (100), 09-12 (100), 09-13 (100), 09-14 (100), 09-15 (100) — by astronomy; check the weather when the night is within four days.

2042-09-03astronomy score per night — click a bar for that night2042-10-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-09-03 Wed	18	—	unknown	01:15–05:15 (marginal, 4.0 h)	72.5° 06:15	7.73	80%	25.0°
2042-09-04 Thu	26	—	unknown	00:55–05:15 (marginal, 4.33 h)	72.5° 06:15	7.78	70%	10.6°
2042-09-05 Fri	38	—	unknown	00:40–05:20 (marginal, 4.67 h)	72.5° 06:10	7.84	59%	3.7°
2042-09-06 Sat	53	—	unknown	01:25–05:20 (good, 3.92 h)	72.6° 06:05	7.89	48%	17.4°
2042-09-07 Sun	70	—	unknown	01:10–05:20 (good, 4.17 h)	72.5° 06:00	7.95	37%	30.8°
2042-09-08 Mon	87	—	unknown	00:50–05:20 (good, 4.5 h)	72.5° 05:55	8.0	27%	44.0°
2042-09-09 Tue	93	—	unknown	00:45–05:25 (good, 4.67 h)	72.5° 05:55	8.06	18%	56.9°
2042-09-10 Wed	98	—	unknown	00:45–05:25 (good, 4.67 h)	72.5° 05:50	8.11	11%	69.5°
2042-09-11 Thu	100	—	unknown	00:40–05:25 (good, 4.75 h)	72.6° 05:45	8.17	6%	82.0°
2042-09-12 Fri	100	—	unknown	00:35–05:25 (good, 4.83 h)	72.5° 05:40	8.22	2%	94.3°
2042-09-13 Sat	100	—	unknown	00:30–05:30 (good, 5.0 h)	72.5° 05:35	8.27	0%	106.4°
2042-09-14 Sun	100	—	unknown	00:25–05:30 (good, 5.08 h)	72.5° 05:35	8.33	0%	118.4°
2042-09-15 Mon	100	—	unknown	00:25–05:30 (good, 5.08 h)	72.5° 05:30	8.38	2%	130.3°
2042-09-16 Tue	100	—	unknown	00:20–05:30 (good, 5.17 h)	72.6° 05:25	8.43	6%	142.1°
2042-09-17 Wed	100	—	unknown	00:15–05:35 (good, 5.33 h)	72.5° 05:20	8.48	11%	153.9°
2042-09-18 Thu	100	—	unknown	00:10–05:35 (good, 5.42 h)	72.5° 05:15	8.54	18%	165.8°
2042-09-19 Fri	100	—	unknown	00:10–05:35 (good, 5.42 h)	72.5° 05:15	8.59	25%	177.6°
2042-09-20 Sat	100	—	unknown	00:05–05:35 (good, 5.5 h)	72.6° 05:10	8.64	34%	170.3°
2042-09-21 Sun	100	—	unknown	00:00–05:35 (good, 5.58 h)	72.6° 05:05	8.69	44%	158.0°
2042-09-22 Mon	100	—	unknown	23:55–05:40 (good, 5.75 h)	72.5° 05:00	8.74	54%	145.5°
2042-09-23 Tue	100	—	unknown	23:55–05:40 (good, 5.75 h)	72.5° 05:00	8.79	64%	132.6°
2042-09-24 Wed	100	—	unknown	23:55–05:40 (good, 5.75 h)	72.5° 04:55	8.84	74%	119.2°
2042-09-25 Thu	100	—	unknown	00:00–05:40 (good, 5.67 h)	72.6° 04:50	8.89	83%	105.4°
2042-09-26 Fri	100	—	unknown	00:05–05:45 (good, 5.67 h)	72.5° 04:45	8.94	91%	91.2°
2042-09-27 Sat	100	—	unknown	01:45–05:45 (good, 4.0 h)	72.5° 04:40	8.99	96%	76.5°
2042-09-28 Sun	58	—	unknown	04:40–05:45 (good, 1.08 h)	72.5° 04:40	9.04	100%	61.4°
2042-09-29 Mon	35	—	unknown	23:45–05:45 (marginal, 6.0 h)	72.6° 04:35	9.09	100%	46.2°
2042-09-30 Tue	20	—	unknown	03:55–05:50 (marginal, 1.92 h)	72.6° 04:30	9.14	97%	31.0°
2042-10-01 Wed	19	—	unknown	23:35–05:50 (marginal, 6.25 h)	72.5° 04:25	9.19	91%	15.9°
2042-10-02 Thu	27	—	unknown	23:10–05:50 (marginal, 6.67 h)	72.5° 04:20	9.23	83%	1.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-09-03&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.