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: 01-19 (93), 01-20 (93), 01-21 (93), 01-22 (93), 01-23 (93) — by astronomy; check the weather when the night is within four days.

2031-01-04astronomy score per night — click a bar for that night2031-02-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-01-04 Sat	90	—	unknown	02:15–06:10 (good, 3.92 h)	50.2° 05:55	11.42	88%	122.8°
2031-01-05 Sun	86	—	unknown	02:20–06:10 (good, 3.83 h)	50.2° 05:50	11.4	93%	111.1°
2031-01-06 Mon	66	—	unknown	02:30–06:10 (good, 3.67 h)	50.2° 05:45	11.39	97%	99.5°
2031-01-07 Tue	55	—	unknown	03:35–06:10 (good, 2.58 h)	50.2° 05:40	11.38	99%	87.8°
2031-01-08 Wed	43	—	unknown	05:00–06:10 (good, 1.17 h)	50.2° 05:40	11.36	100%	76.0°
2031-01-09 Thu	34	—	unknown	01:50–06:10 (marginal, 4.33 h)	50.2° 05:35	11.34	99%	64.1°
2031-01-10 Fri	26	—	unknown	01:55–06:10 (marginal, 4.25 h)	50.2° 05:30	11.33	96%	52.2°
2031-01-11 Sat	22	—	unknown	02:00–06:10 (marginal, 4.17 h)	50.2° 05:25	11.31	91%	40.2°
2031-01-12 Sun	21	—	unknown	01:50–06:10 (marginal, 4.33 h)	50.2° 05:20	11.29	84%	28.3°
2031-01-13 Mon	27	—	unknown	01:25–06:10 (marginal, 4.75 h)	50.2° 05:20	11.27	76%	16.9°
2031-01-14 Tue	36	—	unknown	01:10–06:10 (marginal, 5.0 h)	50.2° 05:15	11.25	67%	9.3°
2031-01-15 Wed	48	—	unknown	03:35–05:30 (good, 1.92 h)	50.2° 05:10	11.23	56%	15.0°
2031-01-16 Thu	65	—	unknown	01:40–06:10 (good, 4.5 h)	50.2° 05:05	11.21	46%	26.9°
2031-01-17 Fri	86	—	unknown	01:15–06:10 (good, 4.92 h)	50.2° 05:00	11.19	35%	40.2°
2031-01-18 Sat	92	—	unknown	01:10–06:10 (good, 5.0 h)	50.2° 05:00	11.16	24%	54.1°
2031-01-19 Sun	93	—	unknown	01:10–06:10 (good, 5.0 h)	50.2° 04:55	11.14	15%	68.5°
2031-01-20 Mon	93	—	unknown	01:05–06:10 (good, 5.08 h)	50.2° 04:50	11.11	7%	83.1°
2031-01-21 Tue	93	—	unknown	01:00–06:05 (good, 5.08 h)	50.2° 04:45	11.09	2%	98.0°
2031-01-22 Wed	93	—	unknown	00:55–06:05 (good, 5.17 h)	50.2° 04:45	11.06	0%	112.8°
2031-01-23 Thu	93	—	unknown	00:50–06:05 (good, 5.25 h)	50.2° 04:40	11.03	1%	127.5°
2031-01-24 Fri	93	—	unknown	00:50–06:05 (good, 5.25 h)	50.2° 04:35	11.01	4%	141.7°
2031-01-25 Sat	93	—	unknown	00:45–06:05 (good, 5.33 h)	50.2° 04:30	10.98	10%	155.2°
2031-01-26 Sun	93	—	unknown	00:40–06:05 (good, 5.42 h)	50.2° 04:25	10.95	18%	166.9°
2031-01-27 Mon	93	—	unknown	00:35–06:05 (good, 5.5 h)	50.2° 04:25	10.92	27%	170.1°
2031-01-28 Tue	93	—	unknown	00:30–06:05 (good, 5.58 h)	50.2° 04:20	10.89	36%	161.0°
2031-01-29 Wed	93	—	unknown	00:30–06:00 (good, 5.5 h)	50.2° 04:15	10.86	46%	149.5°
2031-01-30 Thu	93	—	unknown	00:30–06:00 (good, 5.5 h)	50.2° 04:10	10.83	56%	137.8°
2031-01-31 Fri	93	—	unknown	00:25–06:00 (good, 5.58 h)	50.2° 04:05	10.8	65%	126.0°
2031-02-01 Sat	93	—	unknown	00:30–06:00 (good, 5.5 h)	50.2° 04:05	10.76	74%	114.4°
2031-02-02 Sun	93	—	unknown	00:35–06:00 (good, 5.42 h)	50.2° 04:00	10.73	82%	102.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-01-04&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.