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: 08-31 (100), 09-01 (100), 09-02 (100), 08-30 (98), 08-29 (96) — by astronomy; check the weather when the night is within four days.

2027-08-04astronomy score per night — click a bar for that night2027-09-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-08-04 Wed	37	—	unknown	03:10–04:30 (good, 1.33 h)	72.5° 08:15	6.0	9%	108.0°
2027-08-05 Thu	38	—	unknown	03:05–04:30 (good, 1.42 h)	72.5° 08:10	6.06	17%	122.5°
2027-08-06 Fri	41	—	unknown	03:00–04:35 (good, 1.58 h)	72.5° 08:05	6.11	26%	136.5°
2027-08-07 Sat	43	—	unknown	02:55–04:35 (good, 1.67 h)	72.5° 08:05	6.17	37%	150.1°
2027-08-08 Sun	45	—	unknown	02:55–04:35 (good, 1.67 h)	72.5° 08:00	6.23	47%	163.2°
2027-08-09 Mon	48	—	unknown	02:50–04:40 (good, 1.83 h)	72.5° 07:55	6.28	57%	175.8°
2027-08-10 Tue	49	—	unknown	02:45–04:40 (good, 1.92 h)	72.5° 07:50	6.34	67%	171.6°
2027-08-11 Wed	51	—	unknown	02:40–04:40 (good, 2.0 h)	72.5° 07:45	6.4	76%	159.4°
2027-08-12 Thu	53	—	unknown	02:40–04:40 (good, 2.0 h)	72.5° 07:45	6.46	84%	147.4°
2027-08-13 Fri	55	—	unknown	02:40–04:45 (good, 2.08 h)	72.5° 07:40	6.51	90%	135.5°
2027-08-14 Sat	55	—	unknown	02:40–04:45 (good, 2.08 h)	72.5° 07:35	6.57	95%	123.7°
2027-08-15 Sun	46	—	unknown	02:40–04:45 (good, 2.08 h)	72.5° 07:30	6.63	98%	111.8°
2027-08-16 Mon	41	—	unknown	02:45–04:50 (good, 2.08 h)	72.5° 07:30	6.69	100%	100.0°
2027-08-17 Tue	34	—	unknown	03:30–04:50 (good, 1.33 h)	72.5° 07:25	6.74	100%	88.1°
2027-08-18 Wed	27	—	unknown	04:40–04:50 (good, 0.17 h)	72.5° 07:20	6.8	98%	76.1°
2027-08-19 Thu	22	—	unknown	02:05–04:55 (marginal, 2.83 h)	72.5° 07:15	6.86	94%	63.9°
2027-08-20 Fri	18	—	unknown	02:05–04:55 (marginal, 2.83 h)	72.5° 07:10	6.92	88%	51.7°
2027-08-21 Sat	16	—	unknown	02:05–04:55 (marginal, 2.83 h)	72.5° 07:10	6.97	81%	39.2°
2027-08-22 Sun	17	—	unknown	01:55–05:00 (marginal, 3.08 h)	72.5° 07:05	7.03	72%	26.6°
2027-08-23 Mon	24	—	unknown	01:40–05:00 (marginal, 3.33 h)	72.5° 07:00	7.09	62%	13.6°
2027-08-24 Tue	34	—	unknown	04:25–05:00 (good, 0.58 h)	72.5° 06:55	7.15	52%	1.0°
2027-08-25 Wed	46	—	unknown	02:10–05:00 (good, 2.83 h)	72.5° 06:50	7.2	41%	13.3°
2027-08-26 Thu	60	—	unknown	01:55–05:05 (good, 3.17 h)	72.5° 06:50	7.26	30%	27.2°
2027-08-27 Fri	76	—	unknown	01:40–05:05 (good, 3.42 h)	72.5° 06:45	7.32	20%	41.6°
2027-08-28 Sat	88	—	unknown	01:35–05:05 (good, 3.5 h)	72.5° 06:40	7.37	11%	56.3°
2027-08-29 Sun	96	—	unknown	01:30–05:10 (good, 3.67 h)	72.5° 06:35	7.43	5%	71.3°
2027-08-30 Mon	98	—	unknown	01:25–05:10 (good, 3.75 h)	72.5° 06:35	7.49	1%	86.3°
2027-08-31 Tue	100	—	unknown	01:25–05:10 (good, 3.75 h)	72.5° 06:30	7.54	0%	101.4°
2027-09-01 Wed	100	—	unknown	01:20–05:10 (good, 3.83 h)	72.5° 06:25	7.6	2%	116.3°
2027-09-02 Thu	100	—	unknown	01:15–05:15 (good, 4.0 h)	72.5° 06:20	7.65	7%	130.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-08-04&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.