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.

2027-12-17astronomy score per night — click a bar for that night2028-01-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2028-01-04 Tue	93	—	unknown	02:05–06:10 (good, 4.08 h)	50.2° 05:55	11.42	49%	168.2°
2028-01-05 Wed	93	—	unknown	02:05–06:10 (good, 4.08 h)	50.2° 05:50	11.41	58%	158.5°
2028-01-06 Thu	93	—	unknown	02:05–06:10 (good, 4.08 h)	50.2° 05:45	11.4	68%	146.6°
2028-01-07 Fri	93	—	unknown	02:05–06:10 (good, 4.08 h)	50.2° 05:45	11.38	78%	133.9°
2028-01-08 Sat	93	—	unknown	02:00–06:10 (good, 4.17 h)	50.2° 05:40	11.37	86%	120.6°
2028-01-09 Sun	77	—	unknown	02:10–06:10 (good, 4.0 h)	50.2° 05:35	11.35	93%	106.8°
2028-01-10 Mon	61	—	unknown	03:00–06:10 (good, 3.17 h)	50.2° 05:30	11.33	98%	92.5°
2028-01-11 Tue	46	—	unknown	04:50–06:10 (good, 1.33 h)	50.2° 05:25	11.31	100%	77.8°
2028-01-12 Wed	33	—	unknown	01:45–06:10 (marginal, 4.42 h)	50.2° 05:25	11.3	99%	63.0°
2028-01-13 Thu	24	—	unknown	01:55–06:10 (marginal, 4.25 h)	50.2° 05:20	11.28	95%	48.2°
2028-01-14 Fri	19	—	unknown	01:55–06:10 (marginal, 4.25 h)	50.2° 05:15	11.26	89%	33.7°
2028-01-15 Sat	24	—	unknown	01:25–06:10 (marginal, 4.75 h)	50.2° 05:10	11.24	80%	20.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-12-17&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.