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.

2042-08-21astronomy score per night — click a bar for that night2042-09-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-08-21 Thu	76	—	unknown	02:00–04:55 (good, 2.92 h)	72.5° 07:10	6.99	32%	157.4°
2042-08-22 Fri	80	—	unknown	02:00–05:00 (good, 3.0 h)	72.5° 07:05	7.05	41%	169.3°
2042-08-23 Sat	82	—	unknown	01:55–05:00 (good, 3.08 h)	72.6° 07:00	7.11	50%	178.5°
2042-08-24 Sun	85	—	unknown	01:50–05:00 (good, 3.17 h)	72.5° 06:55	7.17	60%	166.3°
2042-08-25 Mon	87	—	unknown	01:45–05:00 (good, 3.25 h)	72.5° 06:50	7.22	70%	153.7°
2042-08-26 Tue	89	—	unknown	01:45–05:05 (good, 3.33 h)	72.5° 06:50	7.28	79%	140.7°
2042-08-27 Wed	89	—	unknown	01:45–05:05 (good, 3.33 h)	72.5° 06:45	7.34	87%	127.3°
2042-08-28 Thu	87	—	unknown	01:45–05:05 (good, 3.33 h)	72.6° 06:40	7.39	94%	113.4°
2042-08-29 Fri	66	—	unknown	01:55–05:10 (good, 3.25 h)	72.5° 06:35	7.45	98%	99.1°
2042-08-30 Sat	51	—	unknown	02:55–05:10 (good, 2.25 h)	72.5° 06:30	7.51	100%	84.5°
2042-08-31 Sun	37	—	unknown	04:30–05:10 (good, 0.67 h)	72.5° 06:30	7.56	99%	69.6°
2042-09-01 Mon	26	—	unknown	01:20–05:10 (marginal, 3.83 h)	72.5° 06:25	7.62	95%	54.7°
2042-09-02 Tue	19	—	unknown	01:20–05:15 (marginal, 3.92 h)	72.6° 06:20	7.67	88%	39.8°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-08-21&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.