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: 01-10 (93), 01-11 (93), 01-12 (93), 01-13 (93), 01-09 (87) — by astronomy; check the weather when the night is within four days.

2039-12-15astronomy score per night — click a bar for that night2040-01-13

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-12-15 Thu	62	—	unknown	03:25–06:05 (good, 2.67 h)	50.1° 07:15	11.49	0%	81.4°
2039-12-16 Fri	65	—	unknown	03:25–06:05 (good, 2.67 h)	50.1° 07:10	11.5	2%	96.7°
2039-12-17 Sat	67	—	unknown	03:20–06:05 (good, 2.75 h)	50.1° 07:05	11.5	8%	111.8°
2039-12-18 Sun	68	—	unknown	03:15–06:05 (good, 2.83 h)	50.1° 07:00	11.5	15%	126.6°
2039-12-19 Mon	69	—	unknown	03:10–06:05 (good, 2.92 h)	50.1° 07:00	11.51	24%	140.9°
2039-12-20 Tue	71	—	unknown	03:05–06:05 (good, 3.0 h)	50.1° 06:55	11.51	34%	154.8°
2039-12-21 Wed	73	—	unknown	03:05–06:05 (good, 3.0 h)	50.1° 06:50	11.51	45%	168.2°
2039-12-22 Thu	74	—	unknown	03:00–06:05 (good, 3.08 h)	50.1° 06:45	11.51	55%	178.8°
2039-12-23 Fri	77	—	unknown	02:55–06:10 (good, 3.25 h)	50.1° 06:40	11.51	65%	166.2°
2039-12-24 Sat	78	—	unknown	02:50–06:10 (good, 3.33 h)	50.1° 06:40	11.5	74%	153.9°
2039-12-25 Sun	79	—	unknown	02:55–06:10 (good, 3.25 h)	50.1° 06:35	11.5	82%	141.7°
2039-12-26 Mon	78	—	unknown	02:55–06:10 (good, 3.25 h)	50.1° 06:30	11.5	89%	129.7°
2039-12-27 Tue	77	—	unknown	02:50–06:10 (good, 3.33 h)	50.1° 06:25	11.49	94%	117.8°
2039-12-28 Wed	61	—	unknown	03:00–06:10 (good, 3.17 h)	50.1° 06:20	11.49	98%	105.9°
2039-12-29 Thu	50	—	unknown	03:40–06:10 (good, 2.5 h)	50.1° 06:20	11.48	100%	94.1°
2039-12-30 Fri	40	—	unknown	05:00–06:10 (good, 1.17 h)	50.1° 06:15	11.47	100%	82.2°
2039-12-31 Sat	31	—	unknown	02:20–06:10 (marginal, 3.83 h)	50.1° 06:10	11.46	98%	70.3°
2040-01-01 Sun	24	—	unknown	02:30–06:10 (marginal, 3.67 h)	50.1° 06:05	11.45	95%	58.3°
2040-01-02 Mon	19	—	unknown	02:35–06:10 (marginal, 3.58 h)	50.1° 06:05	11.44	90%	46.3°
2040-01-03 Tue	17	—	unknown	02:30–06:10 (marginal, 3.67 h)	50.1° 06:00	11.43	83%	34.1°
2040-01-04 Wed	20	—	unknown	02:10–06:10 (marginal, 4.0 h)	50.1° 05:55	11.42	75%	21.7°
2040-01-05 Thu	28	—	unknown	01:50–06:10 (marginal, 4.33 h)	50.1° 05:50	11.41	66%	9.0°
2040-01-06 Fri	39	—	unknown	01:35–06:10 (marginal, 4.58 h)	50.1° 05:45	11.39	56%	3.9°
2040-01-07 Sat	52	—	unknown	02:20–06:10 (good, 3.83 h)	50.1° 05:45	11.38	45%	17.2°
2040-01-08 Sun	73	—	unknown	01:50–06:10 (good, 4.33 h)	50.1° 05:40	11.36	34%	30.8°
2040-01-09 Mon	87	—	unknown	01:50–06:10 (good, 4.33 h)	50.1° 05:35	11.35	24%	45.0°
2040-01-10 Tue	93	—	unknown	01:45–06:10 (good, 4.42 h)	50.1° 05:30	11.33	15%	59.5°
2040-01-11 Wed	93	—	unknown	01:40–06:10 (good, 4.5 h)	50.1° 05:25	11.31	7%	74.4°
2040-01-12 Thu	93	—	unknown	01:35–06:10 (good, 4.58 h)	50.1° 05:25	11.29	2%	89.5°
2040-01-13 Fri	93	—	unknown	01:35–06:10 (good, 4.58 h)	50.1° 05:20	11.27	0%	104.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-12-15&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.