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 North America Nebula: 08-25 (100), 08-26 (100), 08-27 (100), 08-28 (100), 08-29 (100) — by astronomy; check the weather when the night is within four days.

2027-08-25astronomy score per night — click a bar for that night2027-09-23

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-08-25 Wed	100	—	unknown	21:50–05:00 (good, 7.17 h)	87.3° 00:05	7.2	41%	88.1°
2027-08-26 Thu	100	—	unknown	21:50–05:05 (good, 7.25 h)	87.2° 00:00	7.26	30%	96.2°
2027-08-27 Fri	100	—	unknown	21:45–05:05 (good, 7.33 h)	87.2° 23:55	7.32	20%	104.2°
2027-08-28 Sat	100	—	unknown	21:45–05:05 (good, 7.33 h)	87.2° 23:55	7.37	11%	111.7°
2027-08-29 Sun	100	—	unknown	21:40–05:10 (good, 7.5 h)	87.3° 23:50	7.43	5%	118.1°
2027-08-30 Mon	100	—	unknown	21:40–05:10 (good, 7.5 h)	87.3° 23:45	7.49	1%	122.8°
2027-08-31 Tue	100	—	unknown	21:40–05:10 (good, 7.5 h)	87.2° 23:40	7.54	0%	125.1°
2027-09-01 Wed	100	—	unknown	21:35–05:10 (good, 7.58 h)	87.2° 23:40	7.6	2%	124.6°
2027-09-02 Thu	100	—	unknown	21:35–05:15 (good, 7.67 h)	87.2° 23:35	7.65	7%	121.7°
2027-09-03 Fri	100	—	unknown	21:30–05:15 (good, 7.75 h)	87.3° 23:30	7.71	14%	116.8°
2027-09-04 Sat	100	—	unknown	21:30–05:15 (good, 7.75 h)	87.2° 23:25	7.76	22%	110.7°
2027-09-05 Sun	100	—	unknown	21:30–05:15 (good, 7.75 h)	87.2° 23:20	7.82	32%	103.9°
2027-09-06 Mon	100	—	unknown	21:25–05:20 (good, 7.92 h)	87.2° 23:20	7.87	42%	96.8°
2027-09-07 Tue	100	—	unknown	21:25–05:20 (good, 7.92 h)	87.2° 23:15	7.93	52%	89.6°
2027-09-08 Wed	100	—	unknown	21:20–05:20 (good, 8.0 h)	87.3° 23:10	7.98	61%	82.6°
2027-09-09 Thu	100	—	unknown	21:20–05:20 (good, 8.0 h)	87.2° 23:05	8.04	70%	76.0°
2027-09-10 Fri	97	—	unknown	21:20–05:20 (good, 8.0 h)	87.2° 23:00	8.09	79%	69.8°
2027-09-11 Sat	89	—	unknown	21:15–05:20 (good, 8.08 h)	87.2° 23:00	8.15	86%	64.4°
2027-09-12 Sun	82	—	unknown	00:30–05:15 (good, 4.75 h)	87.3° 22:55	8.2	92%	59.9°
2027-09-13 Mon	58	—	unknown	21:10–05:25 (marginal, 8.25 h)	87.3° 22:50	8.25	96%	56.7°
2027-09-14 Tue	57	—	unknown	21:10–05:30 (marginal, 8.33 h)	87.2° 22:45	8.31	99%	55.0°
2027-09-15 Wed	57	—	unknown	21:10–05:15 (marginal, 8.08 h)	87.2° 22:45	8.36	100%	55.0°
2027-09-16 Thu	61	—	unknown	21:05–21:15 (good, 0.17 h)	87.2° 22:40	8.41	99%	56.9°
2027-09-17 Fri	65	—	unknown	21:05–22:10 (good, 1.08 h)	87.3° 22:35	8.46	96%	60.5°
2027-09-18 Sat	72	—	unknown	21:00–23:45 (good, 2.75 h)	87.2° 22:30	8.52	91%	65.6°
2027-09-19 Sun	78	—	unknown	21:00–01:40 (good, 4.67 h)	87.2° 22:25	8.57	84%	71.7°
2027-09-20 Mon	100	—	unknown	21:00–02:55 (good, 5.92 h)	87.2° 22:25	8.62	76%	78.7°
2027-09-21 Tue	100	—	unknown	20:55–04:05 (good, 7.17 h)	87.2° 22:20	8.67	66%	86.3°
2027-09-22 Wed	100	—	unknown	20:55–04:15 (good, 7.33 h)	87.3° 22:15	8.72	56%	94.1°
2027-09-23 Thu	100	—	unknown	20:55–04:20 (good, 7.42 h)	87.2° 22:10	8.77	44%	102.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-08-25&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.