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.

2040-12-23astronomy score per night — click a bar for that night2041-01-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2040-12-31 Mon	90	—	unknown	02:20–06:10 (good, 3.83 h)	50.1° 06:05	11.46	5%	69.5°
2041-01-01 Tue	92	—	unknown	02:15–06:10 (good, 3.92 h)	50.1° 06:05	11.45	1%	84.2°
2041-01-02 Wed	93	—	unknown	02:15–06:10 (good, 3.92 h)	50.1° 06:00	11.44	0%	99.2°
2041-01-03 Thu	93	—	unknown	02:10–06:10 (good, 4.0 h)	50.1° 05:55	11.42	2%	114.4°
2041-01-04 Fri	93	—	unknown	02:05–06:10 (good, 4.08 h)	50.1° 05:50	11.41	7%	129.5°
2041-01-05 Sat	93	—	unknown	02:00–06:10 (good, 4.17 h)	50.1° 05:50	11.4	14%	144.4°
2041-01-06 Sun	93	—	unknown	01:55–06:10 (good, 4.25 h)	50.1° 05:45	11.38	24%	159.0°
2041-01-07 Mon	93	—	unknown	01:55–06:10 (good, 4.25 h)	50.1° 05:40	11.37	34%	173.2°
2041-01-08 Tue	93	—	unknown	01:50–06:10 (good, 4.33 h)	50.1° 05:35	11.35	45%	172.8°
2041-01-09 Wed	93	—	unknown	01:45–06:10 (good, 4.42 h)	50.1° 05:30	11.34	56%	159.4°
2041-01-10 Thu	93	—	unknown	01:45–06:10 (good, 4.42 h)	50.1° 05:30	11.32	66%	146.3°
2041-01-11 Fri	93	—	unknown	01:45–06:10 (good, 4.42 h)	50.1° 05:25	11.3	75%	133.5°
2041-01-12 Sat	93	—	unknown	01:45–06:10 (good, 4.42 h)	50.1° 05:20	11.28	83%	120.9°
2041-01-13 Sun	93	—	unknown	01:50–06:10 (good, 4.33 h)	50.1° 05:15	11.26	90%	108.6°
2041-01-14 Mon	71	—	unknown	02:10–06:10 (good, 4.0 h)	50.1° 05:10	11.24	95%	96.4°
2041-01-15 Tue	57	—	unknown	03:35–06:10 (good, 2.58 h)	50.1° 05:10	11.22	98%	84.3°
2041-01-16 Wed	43	—	unknown	05:35–06:10 (good, 0.58 h)	50.1° 05:05	11.2	100%	72.4°
2041-01-17 Thu	32	—	unknown	01:25–06:10 (marginal, 4.75 h)	50.1° 05:00	11.17	100%	60.5°
2041-01-18 Fri	23	—	unknown	01:40–06:10 (marginal, 4.5 h)	50.1° 04:55	11.15	97%	48.7°
2041-01-19 Sat	18	—	unknown	03:15–06:10 (marginal, 2.92 h)	50.1° 04:55	11.12	94%	36.8°
2041-01-20 Sun	17	—	unknown	02:30–06:10 (marginal, 3.67 h)	50.1° 04:50	11.1	88%	25.0°
2041-01-21 Mon	22	—	unknown	01:05–06:05 (marginal, 5.0 h)	50.1° 04:45	11.07	82%	13.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-12-23&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.