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: 12-21 (100), 12-22 (100), 12-23 (100), 12-24 (100), 12-25 (100) — by astronomy; check the weather when the night is within four days.

2040-12-16astronomy score per night — click a bar for that night2041-01-14

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-12-16 Sun	28	—	unknown	18:35–22:25 (marginal, 3.83 h)	79.2° 20:15	11.5	98%	38.3°
2040-12-17 Mon	39	—	unknown	18:35–00:35 (marginal, 6.0 h)	79.2° 20:10	11.5	100%	48.8°
2040-12-18 Tue	55	—	unknown	18:35–19:00 (good, 0.42 h)	79.2° 20:05	11.51	100%	59.8°
2040-12-19 Wed	71	—	unknown	18:35–21:20 (good, 2.75 h)	79.2° 20:00	11.51	98%	70.9°
2040-12-20 Thu	79	—	unknown	18:35–23:15 (good, 4.67 h)	79.2° 19:55	11.51	94%	82.1°
2040-12-21 Fri	100	—	unknown	18:35–00:30 (good, 5.92 h)	79.2° 19:55	11.51	89%	93.1°
2040-12-22 Sat	100	—	unknown	18:35–01:00 (good, 6.42 h)	79.2° 19:50	11.51	83%	104.1°
2040-12-23 Sun	100	—	unknown	18:40–01:05 (good, 6.42 h)	79.2° 19:45	11.5	75%	115.1°
2040-12-24 Mon	100	—	unknown	18:40–01:05 (good, 6.42 h)	79.2° 19:40	11.5	67%	125.8°
2040-12-25 Tue	100	—	unknown	18:40–01:05 (good, 6.42 h)	79.2° 19:40	11.5	58%	136.4°
2040-12-26 Wed	100	—	unknown	18:40–01:05 (good, 6.42 h)	79.2° 19:35	11.49	48%	146.3°
2040-12-27 Thu	100	—	unknown	18:40–01:00 (good, 6.33 h)	79.2° 19:30	11.49	38%	154.7°
2040-12-28 Fri	100	—	unknown	18:40–01:00 (good, 6.33 h)	79.2° 19:25	11.48	28%	158.8°
2040-12-29 Sat	100	—	unknown	18:40–00:55 (good, 6.25 h)	79.2° 19:20	11.47	19%	155.9°
2040-12-30 Sun	100	—	unknown	18:40–00:50 (good, 6.17 h)	79.2° 19:20	11.47	11%	147.1°
2040-12-31 Mon	100	—	unknown	18:45–00:45 (good, 6.0 h)	79.2° 19:15	11.46	5%	135.5°
2041-01-01 Tue	100	—	unknown	18:45–00:45 (good, 6.0 h)	79.2° 19:10	11.45	1%	122.4°
2041-01-02 Wed	100	—	unknown	18:45–00:40 (good, 5.92 h)	79.2° 19:05	11.44	0%	108.7°
2041-01-03 Thu	100	—	unknown	18:45–00:35 (good, 5.83 h)	79.2° 19:00	11.42	2%	94.6°
2041-01-04 Fri	100	—	unknown	18:45–00:30 (good, 5.75 h)	79.2° 19:00	11.41	7%	80.5°
2041-01-05 Sat	100	—	unknown	18:45–00:25 (good, 5.67 h)	79.2° 18:55	11.4	14%	66.7°
2041-01-06 Sun	97	—	unknown	18:50–00:25 (good, 5.58 h)	79.2° 18:50	11.38	24%	53.4°
2041-01-07 Mon	87	—	unknown	18:50–00:20 (good, 5.5 h)	79.2° 18:45	11.37	34%	41.0°
2041-01-08 Tue	73	—	unknown	18:50–23:55 (good, 5.08 h)	79.2° 18:45	11.35	45%	30.2°
2041-01-09 Wed	56	—	unknown	19:20–22:25 (good, 3.08 h)	79.2° 18:40	11.34	56%	22.7°
2041-01-10 Thu	39	—	unknown	18:50–00:25 (marginal, 5.58 h)	79.2° 18:35	11.32	66%	21.5°
2041-01-11 Fri	26	—	unknown	18:55–00:10 (marginal, 5.25 h)	79.2° 18:30	11.3	75%	26.9°
2041-01-12 Sat	23	—	unknown	18:55–23:50 (marginal, 4.92 h)	79.2° 18:25	11.28	83%	35.8°
2041-01-13 Sun	25	—	unknown	18:55–23:40 (marginal, 4.75 h)	79.2° 18:25	11.26	90%	46.2°
2041-01-14 Mon	30	—	unknown	18:55–23:40 (marginal, 4.75 h)	79.2° 18:20	11.24	95%	57.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-12-16&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.