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: 02-15 (93), 02-16 (93), 02-17 (93), 02-18 (93), 02-19 (93) — by astronomy; check the weather when the night is within four days.

2031-02-06astronomy score per night — click a bar for that night2031-03-07

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2031-02-19 Wed	93	—	unknown	23:05–05:40 (good, 6.58 h)	50.2° 02:55	10.09	4%	121.3°
2031-02-20 Thu	93	—	unknown	23:00–05:40 (good, 6.67 h)	50.2° 02:50	10.05	1%	135.5°
2031-02-21 Fri	93	—	unknown	23:00–05:35 (good, 6.58 h)	50.2° 02:45	10.01	0%	149.4°
2031-02-22 Sat	93	—	unknown	22:55–05:35 (good, 6.67 h)	50.2° 02:40	9.96	2%	162.3°
2031-02-23 Sun	93	—	unknown	22:50–05:35 (good, 6.75 h)	50.2° 02:35	9.92	7%	170.9°
2031-02-24 Mon	93	—	unknown	22:45–05:35 (good, 6.83 h)	50.2° 02:35	9.88	13%	165.3°
2031-02-25 Tue	93	—	unknown	22:40–05:30 (good, 6.83 h)	50.2° 02:30	9.83	20%	153.9°
2031-02-26 Wed	93	—	unknown	22:40–05:30 (good, 6.83 h)	50.2° 02:25	9.79	29%	141.9°
2031-02-27 Thu	93	—	unknown	22:40–05:30 (good, 6.83 h)	50.2° 02:20	9.75	38%	130.0°
2031-02-28 Fri	93	—	unknown	22:35–05:25 (good, 6.83 h)	50.2° 02:15	9.7	48%	118.2°
2031-03-01 Sat	93	—	unknown	22:40–05:25 (good, 6.75 h)	50.2° 02:15	9.66	57%	106.5°
2031-03-02 Sun	92	—	unknown	22:45–05:25 (good, 6.67 h)	50.2° 02:10	9.61	66%	94.8°
2031-03-03 Mon	90	—	unknown	23:15–05:20 (good, 6.08 h)	50.2° 02:05	9.56	75%	83.1°
2031-03-04 Tue	86	—	unknown	00:45–05:20 (good, 4.58 h)	50.2° 02:00	9.52	83%	71.3°
2031-03-05 Wed	82	—	unknown	03:25–05:20 (good, 1.92 h)	50.2° 02:00	9.47	89%	59.3°
2031-03-06 Thu	45	—	unknown	22:25–05:15 (marginal, 6.83 h)	50.2° 01:55	9.42	95%	47.2°
2031-03-07 Fri	31	—	unknown	00:30–05:15 (marginal, 4.75 h)	50.2° 01:50	9.38	98%	35.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-02-06&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.