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 3C 273: 12-30 (87), 12-29 (77), 12-28 (63), 12-15 (61), 12-13 (60) — by astronomy; check the weather when the night is within four days.

2040-12-01astronomy score per night — click a bar for that night2040-12-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-12-01 Sat	37	—	unknown	04:20–05:55 (good, 1.58 h)	50.1° 08:05	11.34	7%	33.4°
2040-12-02 Sun	41	—	unknown	04:15–05:55 (good, 1.67 h)	50.1° 08:00	11.36	2%	47.3°
2040-12-03 Mon	42	—	unknown	04:10–05:55 (good, 1.75 h)	50.1° 08:00	11.37	0%	61.5°
2040-12-04 Tue	44	—	unknown	04:05–05:55 (good, 1.83 h)	50.1° 07:55	11.39	1%	76.0°
2040-12-05 Wed	46	—	unknown	04:05–05:55 (good, 1.83 h)	50.1° 07:50	11.4	4%	90.7°
2040-12-06 Thu	48	—	unknown	04:00–06:00 (good, 2.0 h)	50.1° 07:45	11.42	10%	105.4°
2040-12-07 Fri	50	—	unknown	03:55–06:00 (good, 2.08 h)	50.1° 07:40	11.43	18%	120.1°
2040-12-08 Sat	52	—	unknown	03:50–06:00 (good, 2.17 h)	50.1° 07:40	11.44	27%	134.7°
2040-12-09 Sun	53	—	unknown	03:45–06:00 (good, 2.25 h)	50.1° 07:35	11.45	38%	149.0°
2040-12-10 Mon	55	—	unknown	03:45–06:00 (good, 2.25 h)	50.1° 07:30	11.46	49%	163.0°
2040-12-11 Tue	57	—	unknown	03:40–06:00 (good, 2.33 h)	50.1° 07:25	11.47	60%	176.7°
2040-12-12 Wed	58	—	unknown	03:35–06:00 (good, 2.42 h)	50.1° 07:20	11.48	71%	169.7°
2040-12-13 Thu	60	—	unknown	03:30–06:05 (good, 2.58 h)	50.1° 07:20	11.48	80%	156.5°
2040-12-14 Fri	60	—	unknown	03:35–06:05 (good, 2.5 h)	50.1° 07:15	11.49	88%	143.5°
2040-12-15 Sat	61	—	unknown	03:35–06:05 (good, 2.5 h)	50.1° 07:10	11.49	94%	130.7°
2040-12-16 Sun	54	—	unknown	03:35–06:05 (good, 2.5 h)	50.1° 07:05	11.5	98%	118.0°
2040-12-17 Mon	45	—	unknown	03:40–06:05 (good, 2.42 h)	50.1° 07:05	11.5	100%	105.6°
2040-12-18 Tue	37	—	unknown	04:30–06:05 (good, 1.58 h)	50.1° 07:00	11.51	100%	93.3°
2040-12-19 Wed	30	—	unknown	05:45–06:05 (good, 0.33 h)	50.1° 06:55	11.51	98%	81.2°
2040-12-20 Thu	23	—	unknown	03:00–06:05 (marginal, 3.08 h)	50.1° 06:50	11.51	94%	69.2°
2040-12-21 Fri	19	—	unknown	03:05–06:05 (marginal, 3.0 h)	50.1° 06:45	11.51	89%	57.3°
2040-12-22 Sat	17	—	unknown	03:05–06:10 (marginal, 3.08 h)	50.1° 06:45	11.51	83%	45.5°
2040-12-23 Sun	17	—	unknown	03:00–06:10 (marginal, 3.17 h)	50.1° 06:40	11.5	75%	33.7°
2040-12-24 Mon	21	—	unknown	02:40–06:10 (marginal, 3.5 h)	50.1° 06:35	11.5	67%	21.8°
2040-12-25 Tue	29	—	unknown	02:25–06:10 (marginal, 3.75 h)	50.1° 06:30	11.5	58%	9.8°
2040-12-26 Wed	39	—	unknown	04:00–06:10 (good, 2.17 h)	50.1° 06:25	11.49	48%	2.6°
2040-12-27 Thu	50	—	unknown	02:55–06:10 (good, 3.25 h)	50.1° 06:25	11.49	38%	15.0°
2040-12-28 Fri	63	—	unknown	02:35–06:10 (good, 3.58 h)	50.1° 06:20	11.48	28%	27.9°
2040-12-29 Sat	77	—	unknown	02:30–06:10 (good, 3.67 h)	50.1° 06:15	11.47	19%	41.3°
2040-12-30 Sun	87	—	unknown	02:25–06:10 (good, 3.75 h)	50.1° 06:10	11.47	11%	55.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-12-01&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.