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: 08-27 (100), 08-28 (100), 08-29 (100), 08-30 (100), 08-31 (100) — by astronomy; check the weather when the night is within four days.

2027-08-18astronomy score per night — click a bar for that night2027-09-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-08-18 Wed	33	—	unknown	23:35–04:50 (marginal, 5.25 h)	79.1° 05:10	6.8	98%	51.3°
2027-08-19 Thu	25	—	unknown	23:35–04:55 (marginal, 5.33 h)	79.1° 05:05	6.86	94%	39.9°
2027-08-20 Fri	22	—	unknown	23:30–04:55 (marginal, 5.42 h)	79.1° 05:00	6.92	88%	28.9°
2027-08-21 Sat	28	—	unknown	23:15–04:55 (marginal, 5.67 h)	79.1° 04:55	6.97	81%	19.1°
2027-08-22 Sun	38	—	unknown	23:05–05:00 (marginal, 5.92 h)	79.1° 04:50	7.03	72%	14.2°
2027-08-23 Mon	52	—	unknown	22:50–05:00 (marginal, 6.17 h)	79.1° 04:50	7.09	62%	18.9°
2027-08-24 Tue	68	—	unknown	23:40–05:00 (good, 5.33 h)	79.1° 04:45	7.15	52%	29.3°
2027-08-25 Wed	83	—	unknown	23:15–05:00 (good, 5.75 h)	79.1° 04:40	7.2	41%	41.5°
2027-08-26 Thu	91	—	unknown	23:10–05:05 (good, 5.92 h)	79.1° 04:35	7.26	30%	54.7°
2027-08-27 Fri	100	—	unknown	23:05–05:05 (good, 6.0 h)	79.1° 04:30	7.32	20%	68.5°
2027-08-28 Sat	100	—	unknown	23:00–05:05 (good, 6.08 h)	79.1° 04:30	7.37	11%	82.8°
2027-08-29 Sun	100	—	unknown	22:55–05:10 (good, 6.25 h)	79.1° 04:25	7.43	5%	97.3°
2027-08-30 Mon	100	—	unknown	22:55–05:10 (good, 6.25 h)	79.1° 04:20	7.49	1%	111.9°
2027-08-31 Tue	100	—	unknown	22:50–05:10 (good, 6.33 h)	79.1° 04:15	7.54	0%	126.3°
2027-09-01 Wed	100	—	unknown	22:45–05:10 (good, 6.42 h)	79.1° 04:15	7.6	2%	140.3°
2027-09-02 Thu	100	—	unknown	22:40–05:15 (good, 6.58 h)	79.1° 04:10	7.65	7%	153.2°
2027-09-03 Fri	100	—	unknown	22:40–05:15 (good, 6.58 h)	79.1° 04:05	7.71	14%	163.3°
2027-09-04 Sat	100	—	unknown	22:35–05:15 (good, 6.67 h)	79.1° 04:00	7.76	22%	165.0°
2027-09-05 Sun	100	—	unknown	22:30–05:15 (good, 6.75 h)	79.1° 03:55	7.82	32%	157.2°
2027-09-06 Mon	100	—	unknown	22:30–05:20 (good, 6.83 h)	79.1° 03:55	7.87	42%	146.3°
2027-09-07 Tue	100	—	unknown	22:25–05:20 (good, 6.92 h)	79.1° 03:50	7.93	52%	134.9°
2027-09-08 Wed	100	—	unknown	22:25–05:20 (good, 6.92 h)	79.1° 03:45	7.98	61%	123.3°
2027-09-09 Thu	100	—	unknown	22:25–05:20 (good, 6.92 h)	79.1° 03:40	8.04	70%	111.8°
2027-09-10 Fri	100	—	unknown	22:25–05:25 (good, 7.0 h)	79.1° 03:35	8.09	79%	100.3°
2027-09-11 Sat	100	—	unknown	22:30–05:25 (good, 6.92 h)	79.1° 03:35	8.15	86%	88.9°
2027-09-12 Sun	100	—	unknown	23:40–05:25 (good, 5.75 h)	79.1° 03:30	8.2	92%	77.4°
2027-09-13 Mon	100	—	unknown	01:35–05:25 (good, 3.83 h)	79.1° 03:25	8.25	96%	65.9°
2027-09-14 Tue	64	—	unknown	04:40–05:30 (good, 0.83 h)	79.1° 03:20	8.31	99%	54.4°
2027-09-15 Wed	45	—	unknown	21:55–05:30 (marginal, 7.58 h)	79.1° 03:20	8.36	100%	42.9°
2027-09-16 Thu	28	—	unknown	22:00–01:15 (marginal, 3.25 h)	79.1° 03:15	8.41	99%	31.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-08-18&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.