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), 09-10 (98), 09-09 (93), 08-26 (89), 08-27 (89) — by astronomy; check the weather when the night is within four days.

2042-08-13astronomy score per night — click a bar for that night2042-09-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-08-13 Wed	57	—	unknown	02:35–04:45 (good, 2.17 h)	72.5° 07:40	6.53	4%	60.0°
2042-08-14 Thu	59	—	unknown	02:30–04:45 (good, 2.25 h)	72.6° 07:35	6.59	1%	72.8°
2042-08-15 Fri	62	—	unknown	02:25–04:50 (good, 2.42 h)	72.5° 07:30	6.65	0%	85.3°
2042-08-16 Sat	65	—	unknown	02:20–04:50 (good, 2.5 h)	72.5° 07:25	6.71	2%	97.7°
2042-08-17 Sun	67	—	unknown	02:15–04:50 (good, 2.58 h)	72.5° 07:25	6.76	5%	109.8°
2042-08-18 Mon	69	—	unknown	02:15–04:50 (good, 2.58 h)	72.5° 07:20	6.82	9%	121.8°
2042-08-19 Tue	72	—	unknown	02:10–04:55 (good, 2.75 h)	72.6° 07:15	6.88	16%	133.7°
2042-08-20 Wed	74	—	unknown	02:05–04:55 (good, 2.83 h)	72.5° 07:10	6.94	23%	145.5°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-08-13&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.