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: 12-31 (90), 12-30 (89), 01-01 (89), 12-29 (88), 01-02 (88) — by astronomy; check the weather when the night is within four days.

2041-12-15astronomy score per night — click a bar for that night2042-01-13

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-12-15 Sun	30	—	unknown	05:15–06:05 (good, 0.83 h)	50.1° 07:10	11.49	47%	7.8°
2041-12-16 Mon	38	—	unknown	03:45–06:05 (good, 2.33 h)	50.1° 07:05	11.5	37%	5.0°
2041-12-17 Tue	47	—	unknown	03:30–06:05 (good, 2.58 h)	50.1° 07:05	11.5	28%	16.6°
2041-12-18 Wed	56	—	unknown	03:15–06:05 (good, 2.83 h)	50.1° 07:00	11.5	20%	28.8°
2041-12-19 Thu	65	—	unknown	03:10–06:05 (good, 2.92 h)	50.1° 06:55	11.51	13%	41.3°
2041-12-20 Fri	72	—	unknown	03:05–06:05 (good, 3.0 h)	50.1° 06:50	11.51	7%	54.1°
2041-12-21 Sat	73	—	unknown	03:00–06:05 (good, 3.08 h)	50.1° 06:50	11.51	2%	67.3°
2041-12-22 Sun	76	—	unknown	02:55–06:10 (good, 3.25 h)	50.1° 06:45	11.51	0%	80.8°
2041-12-23 Mon	78	—	unknown	02:55–06:10 (good, 3.25 h)	50.1° 06:40	11.51	1%	94.6°
2041-12-24 Tue	79	—	unknown	02:50–06:10 (good, 3.33 h)	50.1° 06:35	11.5	3%	108.7°
2041-12-25 Wed	82	—	unknown	02:45–06:10 (good, 3.42 h)	50.1° 06:30	11.5	9%	122.9°
2041-12-26 Thu	83	—	unknown	02:40–06:10 (good, 3.5 h)	50.1° 06:30	11.49	16%	137.2°
2041-12-27 Fri	84	—	unknown	02:40–06:10 (good, 3.5 h)	50.1° 06:25	11.49	26%	151.4°
2041-12-28 Sat	86	—	unknown	02:35–06:10 (good, 3.58 h)	50.1° 06:20	11.48	36%	165.6°
2041-12-29 Sun	88	—	unknown	02:30–06:10 (good, 3.67 h)	50.1° 06:15	11.48	48%	177.6°
2041-12-30 Mon	89	—	unknown	02:25–06:10 (good, 3.75 h)	50.1° 06:10	11.47	59%	165.8°
2041-12-31 Tue	90	—	unknown	02:25–06:10 (good, 3.75 h)	50.1° 06:10	11.46	70%	152.0°
2042-01-01 Wed	89	—	unknown	02:25–06:10 (good, 3.75 h)	50.1° 06:05	11.45	79%	138.3°
2042-01-02 Thu	88	—	unknown	02:25–06:10 (good, 3.75 h)	50.1° 06:00	11.44	87%	124.7°
2042-01-03 Fri	74	—	unknown	02:30–06:10 (good, 3.67 h)	50.1° 05:55	11.43	94%	111.2°
2042-01-04 Sat	61	—	unknown	02:50–06:10 (good, 3.33 h)	50.1° 05:55	11.41	98%	98.0°
2042-01-05 Sun	48	—	unknown	04:15–06:10 (good, 1.92 h)	50.1° 05:50	11.4	100%	85.0°
2042-01-06 Mon	36	—	unknown	01:55–06:10 (marginal, 4.25 h)	50.1° 05:45	11.39	100%	72.2°
2042-01-07 Tue	27	—	unknown	02:05–06:10 (marginal, 4.08 h)	50.1° 05:40	11.37	97%	59.7°
2042-01-08 Wed	20	—	unknown	02:15–06:10 (marginal, 3.92 h)	50.1° 05:35	11.36	93%	47.3°
2042-01-09 Thu	17	—	unknown	02:15–06:10 (marginal, 3.92 h)	50.1° 05:35	11.34	88%	35.2°
2042-01-10 Fri	19	—	unknown	01:55–06:10 (marginal, 4.25 h)	50.1° 05:30	11.32	81%	23.3°
2042-01-11 Sat	26	—	unknown	01:30–06:10 (marginal, 4.67 h)	50.1° 05:25	11.3	73%	11.6°
2042-01-12 Sun	35	—	unknown	01:15–06:10 (marginal, 4.92 h)	50.1° 05:20	11.28	64%	2.6°
2042-01-13 Mon	47	—	unknown	04:30–04:40 (good, 0.17 h)	50.1° 05:15	11.26	55%	12.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-12-15&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.