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: 09-15 (100), 09-16 (100), 09-17 (100), 09-18 (100), 09-19 (100) — by astronomy; check the weather when the night is within four days.

2028-09-05astronomy score per night — click a bar for that night2028-10-04

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-09-05 Tue	27	—	unknown	01:05–05:20 (marginal, 4.25 h)	72.5° 06:05	7.86	96%	54.6°
2028-09-06 Wed	20	—	unknown	01:10–05:20 (marginal, 4.17 h)	72.5° 06:00	7.92	92%	42.8°
2028-09-07 Thu	16	—	unknown	01:10–05:20 (marginal, 4.17 h)	72.5° 06:00	7.97	86%	30.8°
2028-09-08 Fri	20	—	unknown	00:50–05:20 (marginal, 4.5 h)	72.5° 05:55	8.03	79%	18.8°
2028-09-09 Sat	28	—	unknown	00:30–05:25 (marginal, 4.92 h)	72.5° 05:50	8.08	71%	6.5°
2028-09-10 Sun	40	—	unknown	00:20–05:25 (marginal, 5.08 h)	72.5° 05:45	8.13	61%	5.9°
2028-09-11 Mon	55	—	unknown	01:20–05:25 (good, 4.08 h)	72.5° 05:45	8.19	51%	18.7°
2028-09-12 Tue	74	—	unknown	00:50–05:25 (good, 4.58 h)	72.5° 05:40	8.24	41%	31.9°
2028-09-13 Wed	86	—	unknown	00:30–05:30 (good, 5.0 h)	72.5° 05:35	8.29	30%	45.4°
2028-09-14 Thu	94	—	unknown	00:25–05:30 (good, 5.08 h)	72.5° 05:30	8.35	20%	59.5°
2028-09-15 Fri	100	—	unknown	00:20–05:30 (good, 5.17 h)	72.5° 05:25	8.4	12%	74.0°
2028-09-16 Sat	100	—	unknown	00:15–05:30 (good, 5.25 h)	72.5° 05:25	8.45	5%	88.8°
2028-09-17 Sun	100	—	unknown	00:15–05:35 (good, 5.33 h)	72.5° 05:20	8.5	1%	104.0°
2028-09-18 Mon	100	—	unknown	00:10–05:35 (good, 5.42 h)	72.5° 05:15	8.56	0%	119.2°
2028-09-19 Tue	100	—	unknown	00:05–05:35 (good, 5.5 h)	72.5° 05:10	8.61	2%	134.4°
2028-09-20 Wed	100	—	unknown	00:00–05:35 (good, 5.58 h)	72.5° 05:05	8.66	7%	149.4°
2028-09-21 Thu	100	—	unknown	00:00–05:40 (good, 5.67 h)	72.5° 05:05	8.71	14%	164.1°
2028-09-22 Fri	100	—	unknown	23:55–05:40 (good, 5.75 h)	72.5° 05:00	8.76	23%	178.3°
2028-09-23 Sat	100	—	unknown	23:50–05:40 (good, 5.83 h)	72.5° 04:55	8.81	33%	168.0°
2028-09-24 Sun	100	—	unknown	23:45–05:40 (good, 5.92 h)	72.5° 04:50	8.86	44%	154.7°
2028-09-25 Mon	100	—	unknown	23:45–05:45 (good, 6.0 h)	72.5° 04:50	8.91	54%	141.9°
2028-09-26 Tue	100	—	unknown	23:45–05:45 (good, 6.0 h)	72.5° 04:45	8.96	64%	129.4°
2028-09-27 Wed	100	—	unknown	23:40–05:45 (good, 6.08 h)	72.5° 04:40	9.01	73%	117.2°
2028-09-28 Thu	100	—	unknown	23:45–05:45 (good, 6.0 h)	72.5° 04:35	9.06	81%	105.1°
2028-09-29 Fri	100	—	unknown	23:50–05:45 (good, 5.92 h)	72.5° 04:30	9.11	88%	93.2°
2028-09-30 Sat	100	—	unknown	01:00–05:50 (good, 4.83 h)	72.5° 04:30	9.16	93%	81.3°
2028-10-01 Sun	74	—	unknown	02:30–05:50 (good, 3.33 h)	72.5° 04:25	9.2	97%	69.5°
2028-10-02 Mon	56	—	unknown	05:10–05:50 (good, 0.67 h)	72.5° 04:20	9.25	99%	57.7°
2028-10-03 Tue	37	—	unknown	23:35–05:50 (marginal, 6.25 h)	72.5° 04:15	9.3	100%	45.8°
2028-10-04 Wed	23	—	unknown	03:25–05:55 (marginal, 2.5 h)	72.5° 04:10	9.35	98%	33.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-09-05&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.