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: 01-21 (93), 01-22 (93), 01-23 (93), 01-24 (93), 01-25 (93) — by astronomy; check the weather when the night is within four days.

2028-01-13astronomy score per night — click a bar for that night2028-02-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2028-01-16 Sun	33	—	unknown	01:05–06:10 (marginal, 5.08 h)	50.2° 05:05	11.21	70%	10.1°
2028-01-17 Mon	46	—	unknown	00:50–06:10 (marginal, 5.33 h)	50.2° 05:05	11.19	60%	14.3°
2028-01-18 Tue	63	—	unknown	01:35–06:10 (good, 4.58 h)	50.2° 05:00	11.17	49%	26.1°
2028-01-19 Wed	86	—	unknown	01:10–06:10 (good, 5.0 h)	50.2° 04:55	11.14	38%	38.7°
2028-01-20 Thu	91	—	unknown	01:05–06:10 (good, 5.08 h)	50.2° 04:50	11.12	28%	51.3°
2028-01-21 Fri	93	—	unknown	01:00–06:10 (good, 5.17 h)	50.2° 04:50	11.09	20%	63.8°
2028-01-22 Sat	93	—	unknown	00:55–06:05 (good, 5.17 h)	50.2° 04:45	11.07	12%	76.0°
2028-01-23 Sun	93	—	unknown	00:55–06:05 (good, 5.17 h)	50.2° 04:40	11.04	7%	88.2°
2028-01-24 Mon	93	—	unknown	00:50–06:05 (good, 5.25 h)	50.2° 04:35	11.01	3%	100.1°
2028-01-25 Tue	93	—	unknown	00:45–06:05 (good, 5.33 h)	50.2° 04:30	10.99	0%	112.0°
2028-01-26 Wed	93	—	unknown	00:40–06:05 (good, 5.42 h)	50.2° 04:30	10.96	0%	123.7°
2028-01-27 Thu	93	—	unknown	00:35–06:05 (good, 5.5 h)	50.2° 04:25	10.93	2%	135.3°
2028-01-28 Fri	93	—	unknown	00:35–06:05 (good, 5.5 h)	50.2° 04:20	10.9	5%	146.7°
2028-01-29 Sat	93	—	unknown	00:30–06:00 (good, 5.5 h)	50.2° 04:15	10.87	10%	157.7°
2028-01-30 Sun	93	—	unknown	00:25–06:00 (good, 5.58 h)	50.2° 04:10	10.84	16%	167.4°
2028-01-31 Mon	93	—	unknown	00:20–06:00 (good, 5.67 h)	50.2° 04:10	10.81	23%	169.8°
2028-02-01 Tue	93	—	unknown	00:15–06:00 (good, 5.75 h)	50.2° 04:05	10.77	32%	161.7°
2028-02-02 Wed	93	—	unknown	00:15–06:00 (good, 5.75 h)	50.2° 04:00	10.74	41%	150.6°
2028-02-03 Thu	93	—	unknown	00:15–06:00 (good, 5.75 h)	50.2° 03:55	10.71	51%	138.5°
2028-02-04 Fri	93	—	unknown	00:10–05:55 (good, 5.75 h)	50.2° 03:55	10.67	62%	125.8°
2028-02-05 Sat	93	—	unknown	00:15–05:55 (good, 5.67 h)	50.2° 03:50	10.64	72%	112.6°
2028-02-06 Sun	92	—	unknown	00:20–05:55 (good, 5.58 h)	50.2° 03:45	10.6	81%	98.9°
2028-02-07 Mon	88	—	unknown	01:35–05:55 (good, 4.33 h)	50.2° 03:40	10.57	90%	84.6°
2028-02-08 Tue	58	—	unknown	03:55–05:55 (good, 2.0 h)	50.2° 03:35	10.53	96%	70.0°
2028-02-09 Wed	39	—	unknown	00:05–05:50 (marginal, 5.75 h)	50.2° 03:35	10.49	99%	55.1°
2028-02-10 Thu	26	—	unknown	01:50–05:50 (marginal, 4.0 h)	50.2° 03:30	10.46	100%	40.2°
2028-02-11 Fri	20	—	unknown	03:00–05:50 (marginal, 2.83 h)	50.2° 03:25	10.42	97%	25.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-01-13&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.