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), 09-03 (100), 09-04 (100) — by astronomy; check the weather when the night is within four days.

2027-08-27astronomy score per night — click a bar for that night2027-09-25

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2027-09-03 Fri	100	—	unknown	01:10–05:15 (good, 4.08 h)	72.5° 06:15	7.71	14%	144.9°
2027-09-04 Sat	100	—	unknown	01:05–05:15 (good, 4.17 h)	72.5° 06:15	7.76	22%	158.6°
2027-09-05 Sun	100	—	unknown	01:05–05:15 (good, 4.17 h)	72.5° 06:10	7.82	32%	171.8°
2027-09-06 Mon	100	—	unknown	01:00–05:20 (good, 4.33 h)	72.5° 06:05	7.87	42%	175.3°
2027-09-07 Tue	100	—	unknown	00:55–05:20 (good, 4.42 h)	72.5° 06:00	7.93	52%	162.9°
2027-09-08 Wed	100	—	unknown	00:50–05:20 (good, 4.5 h)	72.5° 05:55	7.98	61%	150.8°
2027-09-09 Thu	100	—	unknown	00:55–05:20 (good, 4.42 h)	72.5° 05:55	8.04	70%	138.8°
2027-09-10 Fri	100	—	unknown	00:50–05:25 (good, 4.58 h)	72.5° 05:50	8.09	79%	126.9°
2027-09-11 Sat	100	—	unknown	00:50–05:25 (good, 4.58 h)	72.5° 05:45	8.15	86%	115.1°
2027-09-12 Sun	100	—	unknown	00:55–05:25 (good, 4.5 h)	72.5° 05:40	8.2	92%	103.3°
2027-09-13 Mon	100	—	unknown	01:20–05:25 (good, 4.08 h)	72.5° 05:40	8.25	96%	91.3°
2027-09-14 Tue	65	—	unknown	02:35–05:30 (good, 2.92 h)	72.5° 05:35	8.31	99%	79.3°
2027-09-15 Wed	49	—	unknown	04:30–05:30 (good, 1.0 h)	72.5° 05:30	8.36	100%	67.1°
2027-09-16 Thu	34	—	unknown	00:25–05:30 (marginal, 5.08 h)	72.5° 05:25	8.41	99%	54.8°
2027-09-17 Fri	23	—	unknown	00:35–05:30 (marginal, 4.92 h)	72.5° 05:20	8.46	96%	42.3°
2027-09-18 Sat	16	—	unknown	03:00–05:35 (marginal, 2.58 h)	72.5° 05:20	8.52	91%	29.6°
2027-09-19 Sun	19	—	unknown	00:15–05:35 (marginal, 5.33 h)	72.5° 05:15	8.57	84%	16.7°
2027-09-20 Mon	28	—	unknown	23:55–05:35 (marginal, 5.67 h)	72.5° 05:10	8.62	76%	3.6°
2027-09-21 Tue	41	—	unknown	23:40–05:35 (marginal, 5.92 h)	72.5° 05:05	8.67	66%	9.8°
2027-09-22 Wed	59	—	unknown	01:10–04:10 (good, 3.0 h)	72.5° 05:00	8.72	56%	23.4°
2027-09-23 Thu	75	—	unknown	00:10–05:40 (good, 5.5 h)	72.5° 05:00	8.77	44%	37.3°
2027-09-24 Fri	87	—	unknown	23:50–05:40 (good, 5.83 h)	72.5° 04:55	8.82	33%	51.4°
2027-09-25 Sat	97	—	unknown	23:45–05:40 (good, 5.92 h)	72.5° 04:50	8.87	23%	65.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-08-27&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.