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), 01-01 (91), 12-31 (90), 12-30 (88) — by astronomy; check the weather when the night is within four days.

2027-12-05astronomy score per night — click a bar for that night2028-01-03

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-12-05 Sun	45	—	unknown	04:05–05:55 (good, 1.83 h)	50.2° 07:50	11.39	47%	153.2°
2027-12-06 Mon	46	—	unknown	04:00–05:55 (good, 1.92 h)	50.2° 07:50	11.4	57%	163.9°
2027-12-07 Tue	49	—	unknown	04:00–06:00 (good, 2.0 h)	50.2° 07:45	11.42	66%	170.6°
2027-12-08 Wed	50	—	unknown	03:55–06:00 (good, 2.08 h)	50.2° 07:40	11.43	75%	165.3°
2027-12-09 Thu	52	—	unknown	03:55–06:00 (good, 2.08 h)	50.2° 07:35	11.44	83%	154.2°
2027-12-10 Fri	52	—	unknown	03:55–06:00 (good, 2.08 h)	50.2° 07:35	11.45	90%	141.6°
2027-12-11 Sat	46	—	unknown	03:50–06:00 (good, 2.17 h)	50.2° 07:30	11.46	96%	128.4°
2027-12-12 Sun	43	—	unknown	03:55–06:00 (good, 2.08 h)	50.2° 07:25	11.47	99%	114.6°
2027-12-13 Mon	35	—	unknown	04:05–06:00 (good, 1.92 h)	50.2° 07:20	11.48	100%	100.5°
2027-12-14 Tue	28	—	unknown	05:30–06:05 (good, 0.58 h)	50.2° 07:15	11.48	98%	86.1°
2027-12-15 Wed	22	—	unknown	03:20–06:05 (marginal, 2.75 h)	50.2° 07:15	11.49	93%	71.6°
2027-12-16 Thu	18	—	unknown	03:20–06:05 (marginal, 2.75 h)	50.2° 07:10	11.5	86%	57.2°
2027-12-17 Fri	17	—	unknown	03:15–06:05 (marginal, 2.83 h)	50.2° 07:05	11.5	77%	42.9°
2027-12-18 Sat	19	—	unknown	03:05–06:05 (marginal, 3.0 h)	50.2° 07:00	11.5	66%	29.1°
2027-12-19 Sun	28	—	unknown	02:50–06:05 (marginal, 3.25 h)	50.2° 06:55	11.51	55%	16.5°
2027-12-20 Mon	37	—	unknown	03:35–06:05 (good, 2.5 h)	50.2° 06:55	11.51	44%	9.4°
2027-12-21 Tue	48	—	unknown	03:20–06:05 (good, 2.75 h)	50.2° 06:50	11.51	33%	16.8°
2027-12-22 Wed	59	—	unknown	03:00–06:05 (good, 3.08 h)	50.2° 06:45	11.51	24%	28.8°
2027-12-23 Thu	71	—	unknown	02:55–06:10 (good, 3.25 h)	50.2° 06:40	11.51	15%	41.4°
2027-12-24 Fri	78	—	unknown	02:50–06:10 (good, 3.33 h)	50.2° 06:40	11.5	8%	54.1°
2027-12-25 Sat	81	—	unknown	02:45–06:10 (good, 3.42 h)	50.2° 06:35	11.5	4%	66.6°
2027-12-26 Sun	82	—	unknown	02:45–06:10 (good, 3.42 h)	50.2° 06:30	11.5	1%	79.0°
2027-12-27 Mon	84	—	unknown	02:40–06:10 (good, 3.5 h)	50.2° 06:25	11.49	0%	91.2°
2027-12-28 Tue	86	—	unknown	02:35–06:10 (good, 3.58 h)	50.2° 06:20	11.49	1%	103.3°
2027-12-29 Wed	87	—	unknown	02:30–06:10 (good, 3.67 h)	50.2° 06:20	11.48	4%	115.2°
2027-12-30 Thu	88	—	unknown	02:25–06:10 (good, 3.75 h)	50.2° 06:15	11.47	9%	126.9°
2027-12-31 Fri	90	—	unknown	02:25–06:10 (good, 3.75 h)	50.2° 06:10	11.46	15%	138.4°
2028-01-01 Sat	91	—	unknown	02:20–06:10 (good, 3.83 h)	50.2° 06:05	11.45	22%	149.8°
2028-01-02 Sun	93	—	unknown	02:15–06:10 (good, 3.92 h)	50.2° 06:00	11.44	30%	160.6°
2028-01-03 Mon	93	—	unknown	02:10–06:10 (good, 4.0 h)	50.2° 06:00	11.43	39%	169.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-12-05&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.