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: 09-21 (100), 09-22 (100), 09-23 (100), 09-24 (100), 09-25 (100) — by astronomy; check the weather when the night is within four days.

2041-09-21astronomy score per night — click a bar for that night2041-10-20

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2041-10-13 Sun	84	—	unknown	20:15–23:55 (good, 3.67 h)	79.2° 01:25	9.75	78%	44.8°
2041-10-14 Mon	91	—	unknown	20:15–03:50 (good, 7.58 h)	79.2° 01:20	9.79	69%	56.6°
2041-10-15 Tue	98	—	unknown	20:15–05:30 (good, 9.25 h)	79.2° 01:20	9.84	60%	68.4°
2041-10-16 Wed	100	—	unknown	20:15–06:05 (good, 9.83 h)	79.2° 01:15	9.88	50%	80.0°
2041-10-17 Thu	100	—	unknown	20:10–06:05 (good, 9.92 h)	79.2° 01:10	9.92	40%	91.4°
2041-10-18 Fri	100	—	unknown	20:10–06:10 (good, 10.0 h)	79.2° 01:05	9.97	31%	102.6°
2041-10-19 Sat	100	—	unknown	20:10–06:10 (good, 10.0 h)	79.2° 01:00	10.01	22%	113.7°
2041-10-20 Sun	100	—	unknown	20:05–06:10 (good, 10.08 h)	79.2° 01:00	10.05	15%	124.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-09-21&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.