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: 04-25 (93), 04-26 (93), 04-27 (93), 04-28 (93), 04-29 (93) — by astronomy; check the weather when the night is within four days.

2035-04-22astronomy score per night — click a bar for that night2035-05-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2035-04-22 Sun	25	—	unknown	21:55–03:15 (marginal, 5.33 h)	50.2° 23:50	6.9	100%	30.9°
2035-04-23 Mon	39	—	unknown	21:55–03:30 (marginal, 5.58 h)	50.2° 23:45	6.84	98%	43.1°
2035-04-24 Tue	79	—	unknown	22:00–23:25 (good, 1.42 h)	50.2° 23:40	6.78	94%	55.1°
2035-04-25 Wed	93	—	unknown	22:00–01:30 (good, 3.5 h)	50.2° 23:35	6.72	90%	67.0°
2035-04-26 Thu	93	—	unknown	22:00–02:45 (good, 4.75 h)	50.2° 23:35	6.67	83%	78.8°
2035-04-27 Fri	93	—	unknown	22:05–03:00 (good, 4.92 h)	50.2° 23:30	6.61	75%	90.6°
2035-04-28 Sat	93	—	unknown	22:05–03:05 (good, 5.0 h)	50.2° 23:25	6.55	67%	102.5°
2035-04-29 Sun	93	—	unknown	22:05–03:05 (good, 5.0 h)	50.2° 23:20	6.49	57%	114.5°
2035-04-30 Mon	93	—	unknown	22:10–03:05 (good, 4.92 h)	50.2° 23:20	6.43	48%	126.6°
2035-05-01 Tue	93	—	unknown	22:10–03:05 (good, 4.92 h)	50.2° 23:15	6.37	38%	139.0°
2035-05-02 Wed	93	—	unknown	22:10–03:00 (good, 4.83 h)	50.2° 23:10	6.32	28%	151.8°
2035-05-03 Thu	93	—	unknown	22:10–03:00 (good, 4.83 h)	50.2° 23:05	6.26	19%	164.9°
2035-05-04 Fri	93	—	unknown	22:15–02:55 (good, 4.67 h)	50.2° 23:00	6.2	11%	177.0°
2035-05-05 Sat	93	—	unknown	22:15–02:50 (good, 4.58 h)	50.2° 23:00	6.14	5%	166.7°
2035-05-06 Sun	93	—	unknown	22:15–02:45 (good, 4.5 h)	50.2° 22:55	6.09	1%	152.3°
2035-05-07 Mon	93	—	unknown	22:20–02:40 (good, 4.33 h)	50.2° 22:50	6.03	0%	137.5°
2035-05-08 Tue	93	—	unknown	22:20–02:40 (good, 4.33 h)	50.2° 22:45	5.97	2%	122.6°
2035-05-09 Wed	93	—	unknown	22:20–02:35 (good, 4.25 h)	50.2° 22:40	5.92	7%	107.5°
2035-05-10 Thu	93	—	unknown	22:25–02:30 (good, 4.08 h)	50.2° 22:40	5.86	14%	92.7°
2035-05-11 Fri	89	—	unknown	22:25–02:25 (good, 4.0 h)	50.2° 22:35	5.81	23%	78.0°
2035-05-12 Sat	77	—	unknown	22:25–02:20 (good, 3.92 h)	50.2° 22:30	5.75	33%	63.7°
2035-05-13 Sun	60	—	unknown	22:30–02:20 (good, 3.83 h)	50.2° 22:25	5.7	44%	49.8°
2035-05-14 Mon	43	—	unknown	22:30–01:45 (good, 3.25 h)	50.2° 22:20	5.64	55%	36.2°
2035-05-15 Tue	31	—	unknown	22:30–02:35 (marginal, 4.08 h)	50.2° 22:20	5.59	66%	23.0°
2035-05-16 Wed	23	—	unknown	22:35–02:25 (marginal, 3.83 h)	50.2° 22:15	5.53	75%	10.3°
2035-05-17 Thu	17	—	unknown	22:35–02:10 (marginal, 3.58 h)	50.2° 22:10	5.48	83%	3.9°
2035-05-18 Fri	14	—	unknown	22:35–01:55 (marginal, 3.33 h)	50.2° 22:05	5.43	90%	15.5°
2035-05-19 Sat	12	—	unknown	22:40–01:35 (marginal, 2.92 h)	50.2° 22:05	5.38	95%	27.7°
2035-05-20 Sun	16	—	unknown	22:40–01:40 (marginal, 3.0 h)	50.2° 22:00	5.33	98%	39.8°
2035-05-21 Mon	22	—	unknown	22:40–01:50 (marginal, 3.17 h)	50.2° 21:55	5.28	100%	51.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-04-22&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.