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: 01-20 (93), 01-21 (93), 01-22 (93), 01-23 (93), 01-24 (93) — by astronomy; check the weather when the night is within four days.

2031-01-20astronomy score per night — click a bar for that night2031-02-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2031-02-03 Mon	91	—	unknown	01:00–06:00 (good, 5.0 h)	50.2° 03:55	10.7	88%	91.0°
2031-02-04 Tue	88	—	unknown	02:25–05:55 (good, 3.5 h)	50.2° 03:50	10.66	94%	79.3°
2031-02-05 Wed	54	—	unknown	04:25–05:55 (good, 1.5 h)	50.2° 03:50	10.63	97%	67.4°
2031-02-06 Thu	40	—	unknown	00:15–05:55 (marginal, 5.67 h)	50.2° 03:45	10.59	100%	55.4°
2031-02-07 Fri	29	—	unknown	01:05–05:55 (marginal, 4.83 h)	50.2° 03:40	10.56	100%	43.3°
2031-02-08 Sat	22	—	unknown	02:50–05:55 (marginal, 3.08 h)	50.2° 03:35	10.52	98%	31.2°
2031-02-09 Sun	22	—	unknown	00:10–05:50 (marginal, 5.67 h)	50.2° 03:30	10.48	94%	19.4°
2031-02-10 Mon	27	—	unknown	23:40–05:50 (marginal, 6.17 h)	50.2° 03:30	10.45	88%	10.0°
2031-02-11 Tue	36	—	unknown	23:20–05:50 (marginal, 6.5 h)	50.2° 03:25	10.41	81%	12.6°
2031-02-12 Wed	51	—	unknown	23:05–05:50 (marginal, 6.75 h)	50.2° 03:20	10.37	72%	23.9°
2031-02-13 Thu	84	—	unknown	23:30–04:40 (good, 5.17 h)	50.2° 03:15	10.33	61%	36.8°
2031-02-14 Fri	90	—	unknown	23:25–05:45 (good, 6.33 h)	50.2° 03:10	10.29	50%	50.2°
2031-02-15 Sat	93	—	unknown	23:20–05:45 (good, 6.42 h)	50.2° 03:10	10.25	39%	64.0°
2031-02-16 Sun	93	—	unknown	23:20–05:45 (good, 6.42 h)	50.2° 03:05	10.21	28%	78.1°
2031-02-17 Mon	93	—	unknown	23:15–05:40 (good, 6.42 h)	50.2° 03:00	10.17	18%	92.4°
2031-02-18 Tue	93	—	unknown	23:10–05:40 (good, 6.5 h)	50.2° 02:55	10.13	10%	106.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-01-20&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.