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: 01-02 (93), 01-03 (93), 01-04 (93), 01-05 (93), 01-06 (93) — by astronomy; check the weather when the night is within four days.

2038-12-20astronomy score per night — click a bar for that night2039-01-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-12-20 Mon	46	—	unknown	03:25–06:05 (good, 2.67 h)	50.1° 06:55	11.51	33%	13.2°
2038-12-21 Tue	57	—	unknown	03:00–06:05 (good, 3.08 h)	50.1° 06:50	11.51	23%	27.5°
2038-12-22 Wed	69	—	unknown	03:00–06:10 (good, 3.17 h)	50.1° 06:45	11.51	14%	42.2°
2038-12-23 Thu	76	—	unknown	02:55–06:10 (good, 3.25 h)	50.1° 06:40	11.51	6%	57.0°
2038-12-24 Fri	79	—	unknown	02:50–06:10 (good, 3.33 h)	50.1° 06:35	11.5	2%	72.0°
2038-12-25 Sat	81	—	unknown	02:45–06:10 (good, 3.42 h)	50.1° 06:35	11.5	0%	86.8°
2038-12-26 Sun	82	—	unknown	02:40–06:10 (good, 3.5 h)	50.1° 06:30	11.5	1%	101.5°
2038-12-27 Mon	84	—	unknown	02:40–06:10 (good, 3.5 h)	50.1° 06:25	11.49	5%	115.8°
2038-12-28 Tue	86	—	unknown	02:35–06:10 (good, 3.58 h)	50.1° 06:20	11.48	11%	129.7°
2038-12-29 Wed	87	—	unknown	02:30–06:10 (good, 3.67 h)	50.1° 06:15	11.48	18%	143.2°
2038-12-30 Thu	88	—	unknown	02:25–06:10 (good, 3.75 h)	50.1° 06:15	11.47	27%	156.2°
2038-12-31 Fri	90	—	unknown	02:25–06:10 (good, 3.75 h)	50.1° 06:10	11.46	37%	168.9°
2039-01-01 Sat	91	—	unknown	02:20–06:10 (good, 3.83 h)	50.1° 06:05	11.45	46%	178.7°
2039-01-02 Sun	93	—	unknown	02:15–06:10 (good, 3.92 h)	50.1° 06:00	11.44	56%	166.7°
2039-01-03 Mon	93	—	unknown	02:10–06:10 (good, 4.0 h)	50.1° 06:00	11.43	65%	154.8°
2039-01-04 Tue	93	—	unknown	02:15–06:10 (good, 3.92 h)	50.1° 05:55	11.42	74%	143.0°
2039-01-05 Wed	93	—	unknown	02:10–06:10 (good, 4.0 h)	50.1° 05:50	11.4	82%	131.2°
2039-01-06 Thu	93	—	unknown	02:10–06:10 (good, 4.0 h)	50.1° 05:45	11.39	88%	119.3°
2039-01-07 Fri	86	—	unknown	02:15–06:10 (good, 3.92 h)	50.1° 05:40	11.38	94%	107.3°
2039-01-08 Sat	63	—	unknown	02:45–06:10 (good, 3.42 h)	50.1° 05:40	11.36	98%	95.1°
2039-01-09 Sun	49	—	unknown	04:15–06:10 (good, 1.92 h)	50.1° 05:35	11.34	100%	82.7°
2039-01-10 Mon	37	—	unknown	01:45–06:10 (marginal, 4.42 h)	50.1° 05:30	11.33	100%	70.1°
2039-01-11 Tue	27	—	unknown	01:55–06:10 (marginal, 4.25 h)	50.1° 05:25	11.31	98%	57.2°
2039-01-12 Wed	20	—	unknown	02:05–06:10 (marginal, 4.08 h)	50.1° 05:20	11.29	94%	44.2°
2039-01-13 Thu	16	—	unknown	02:55–06:10 (marginal, 3.25 h)	50.1° 05:20	11.27	88%	31.0°
2039-01-14 Fri	21	—	unknown	01:35–06:10 (marginal, 4.58 h)	50.1° 05:15	11.25	80%	17.6°
2039-01-15 Sat	29	—	unknown	01:10–06:10 (marginal, 5.0 h)	50.1° 05:10	11.23	70%	4.0°
2039-01-16 Sun	43	—	unknown	00:55–06:10 (marginal, 5.25 h)	50.1° 05:05	11.21	59%	9.8°
2039-01-17 Mon	58	—	unknown	01:40–06:10 (good, 4.5 h)	50.1° 05:05	11.18	48%	23.8°
2039-01-18 Tue	83	—	unknown	01:10–06:10 (good, 5.0 h)	50.1° 05:00	11.16	37%	37.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-12-20&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.