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: 08-09 (47), 08-08 (46), 08-07 (43), 08-06 (42), 08-10 (42) — by astronomy; check the weather when the night is within four days.

2041-07-20astronomy score per night — click a bar for that night2041-08-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-07-20 Sat	4	—	unknown	03:40–04:05 (marginal, 0.42 h)	72.5° 09:10	5.24	44%	24.7°
2041-07-21 Sun	7	—	unknown	03:35–04:10 (marginal, 0.58 h)	72.5° 09:10	5.29	34%	11.5°
2041-07-22 Mon	9	—	unknown	03:30–04:55 (marginal, 1.42 h)	72.5° 09:05	5.34	24%	3.2°
2041-07-23 Tue	12	—	unknown	04:00–04:10 (good, 0.17 h)	72.5° 09:00	5.39	16%	15.0°
2041-07-24 Wed	16	—	unknown	03:55–04:15 (good, 0.33 h)	72.5° 08:55	5.44	9%	27.4°
2041-07-25 Thu	19	—	unknown	03:45–04:15 (good, 0.5 h)	72.5° 08:55	5.49	4%	39.8°
2041-07-26 Fri	20	—	unknown	03:45–04:15 (good, 0.5 h)	72.5° 08:50	5.54	1%	52.0°
2041-07-27 Sat	23	—	unknown	03:40–04:20 (good, 0.67 h)	72.5° 08:45	5.6	0%	64.1°
2041-07-28 Sun	24	—	unknown	03:35–04:20 (good, 0.75 h)	72.5° 08:40	5.65	1%	76.1°
2041-07-29 Mon	26	—	unknown	03:30–04:20 (good, 0.83 h)	72.5° 08:35	5.7	3%	87.9°
2041-07-30 Tue	28	—	unknown	03:25–04:25 (good, 1.0 h)	72.5° 08:35	5.76	8%	99.7°
2041-07-31 Wed	30	—	unknown	03:25–04:25 (good, 1.0 h)	72.5° 08:30	5.81	13%	111.5°
2041-08-01 Thu	32	—	unknown	03:20–04:25 (good, 1.08 h)	72.5° 08:25	5.87	20%	123.4°
2041-08-02 Fri	34	—	unknown	03:15–04:30 (good, 1.25 h)	72.5° 08:20	5.92	28%	135.3°
2041-08-03 Sat	35	—	unknown	03:10–04:30 (good, 1.33 h)	72.5° 08:15	5.98	38%	147.4°
2041-08-04 Sun	38	—	unknown	03:05–04:30 (good, 1.42 h)	72.5° 08:15	6.03	47%	159.7°
2041-08-05 Mon	39	—	unknown	03:05–04:30 (good, 1.42 h)	72.5° 08:10	6.09	57%	172.1°
2041-08-06 Tue	42	—	unknown	03:00–04:35 (good, 1.58 h)	72.5° 08:05	6.15	68%	174.0°
2041-08-07 Wed	43	—	unknown	02:55–04:35 (good, 1.67 h)	72.5° 08:00	6.2	77%	160.8°
2041-08-08 Thu	46	—	unknown	02:50–04:35 (good, 1.75 h)	72.5° 08:00	6.26	86%	146.9°
2041-08-09 Fri	47	—	unknown	02:55–04:40 (good, 1.75 h)	72.5° 07:55	6.32	93%	132.5°
2041-08-10 Sat	42	—	unknown	02:55–04:40 (good, 1.75 h)	72.5° 07:50	6.38	98%	117.7°
2041-08-11 Sun	35	—	unknown	03:00–04:40 (good, 1.67 h)	72.5° 07:45	6.43	100%	102.6°
2041-08-12 Mon	29	—	unknown	03:40–04:45 (good, 1.08 h)	72.5° 07:40	6.49	99%	87.4°
2041-08-13 Tue	22	—	unknown	02:15–04:45 (marginal, 2.5 h)	72.5° 07:40	6.55	95%	72.3°
2041-08-14 Wed	18	—	unknown	02:20–04:45 (marginal, 2.42 h)	72.5° 07:35	6.61	88%	57.3°
2041-08-15 Thu	16	—	unknown	02:20–04:50 (marginal, 2.5 h)	72.5° 07:30	6.66	79%	42.7°
2041-08-16 Fri	16	—	unknown	02:10–04:50 (marginal, 2.67 h)	72.5° 07:25	6.72	69%	28.5°
2041-08-17 Sat	23	—	unknown	01:55–04:50 (marginal, 2.92 h)	72.5° 07:20	6.78	59%	14.8°
2041-08-18 Sun	32	—	unknown	03:35–04:55 (good, 1.33 h)	72.5° 07:20	6.84	48%	2.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-07-20&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.