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 Triangulum Pinwheel: 09-18 (100), 09-19 (100), 09-20 (100), 09-21 (100), 09-22 (100) — by astronomy; check the weather when the night is within four days.

2041-09-13astronomy score per night — click a bar for that night2041-10-12

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-09-13 Fri	43	—	unknown	21:35–05:30 (marginal, 7.92 h)	79.2° 03:25	8.29	83%	20.4°
2041-09-14 Sat	60	—	unknown	21:50–21:55 (good, 0.08 h)	79.2° 03:20	8.34	74%	27.3°
2041-09-15 Sun	81	—	unknown	21:50–02:45 (good, 4.92 h)	79.2° 03:15	8.39	63%	37.7°
2041-09-16 Mon	87	—	unknown	21:45–05:30 (good, 7.75 h)	79.2° 03:10	8.44	53%	49.0°
2041-09-17 Tue	94	—	unknown	21:40–05:35 (good, 7.92 h)	79.2° 03:10	8.5	43%	60.5°
2041-09-18 Wed	100	—	unknown	21:35–05:35 (good, 8.0 h)	79.2° 03:05	8.55	33%	72.0°
2041-09-19 Thu	100	—	unknown	21:35–05:35 (good, 8.0 h)	79.2° 03:00	8.6	25%	83.4°
2041-09-20 Fri	100	—	unknown	21:30–05:35 (good, 8.08 h)	79.2° 02:55	8.65	17%	94.6°
2041-09-21 Sat	100	—	unknown	21:25–05:40 (good, 8.25 h)	79.2° 02:50	8.7	10%	105.8°
2041-09-22 Sun	100	—	unknown	21:20–05:40 (good, 8.33 h)	79.2° 02:50	8.75	5%	116.8°
2041-09-23 Mon	100	—	unknown	21:15–05:40 (good, 8.42 h)	79.2° 02:45	8.8	2%	127.6°
2041-09-24 Tue	100	—	unknown	21:15–05:40 (good, 8.42 h)	79.2° 02:40	8.85	0%	138.2°
2041-09-25 Wed	100	—	unknown	21:10–05:40 (good, 8.5 h)	79.2° 02:35	8.9	0%	148.0°
2041-09-26 Thu	100	—	unknown	21:05–05:45 (good, 8.67 h)	79.2° 02:35	8.95	2%	156.2°
2041-09-27 Fri	100	—	unknown	21:00–05:45 (good, 8.75 h)	79.2° 02:30	9.0	6%	160.4°
2041-09-28 Sat	100	—	unknown	20:55–05:45 (good, 8.83 h)	79.2° 02:25	9.05	12%	157.8°
2041-09-29 Sun	100	—	unknown	20:55–05:45 (good, 8.83 h)	79.2° 02:20	9.1	19%	150.0°
2041-09-30 Mon	100	—	unknown	20:50–05:50 (good, 9.0 h)	79.2° 02:15	9.15	27%	139.7°
2041-10-01 Tue	100	—	unknown	20:50–05:50 (good, 9.0 h)	79.2° 02:15	9.2	37%	128.2°
2041-10-02 Wed	100	—	unknown	20:45–05:50 (good, 9.08 h)	79.2° 02:10	9.24	48%	116.0°
2041-10-03 Thu	100	—	unknown	20:50–05:50 (good, 9.0 h)	79.2° 02:05	9.29	59%	103.2°
2041-10-04 Fri	100	—	unknown	20:50–05:50 (good, 9.0 h)	79.2° 02:00	9.34	70%	90.0°
2041-10-05 Sat	100	—	unknown	21:15–05:55 (good, 8.67 h)	79.2° 01:55	9.39	80%	76.4°
2041-10-06 Sun	100	—	unknown	23:15–05:55 (good, 6.67 h)	79.2° 01:55	9.43	88%	62.7°
2041-10-07 Mon	91	—	unknown	03:50–05:55 (good, 2.08 h)	79.2° 01:50	9.48	95%	49.0°
2041-10-08 Tue	50	—	unknown	20:25–05:55 (marginal, 9.5 h)	79.2° 01:45	9.53	99%	36.0°
2041-10-09 Wed	32	—	unknown	20:25–23:55 (marginal, 3.5 h)	79.2° 01:40	9.57	100%	25.0°
2041-10-10 Thu	34	—	unknown	20:20–00:20 (marginal, 4.0 h)	79.2° 01:40	9.62	98%	19.6°
2041-10-11 Fri	41	—	unknown	20:20–01:45 (marginal, 5.42 h)	79.2° 01:35	9.66	94%	23.6°
2041-10-12 Sat	74	—	unknown	20:20–20:25 (good, 0.08 h)	79.2° 01:30	9.71	87%	33.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-09-13&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.