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: 05-04 (89), 05-05 (84), 05-20 (77), 05-19 (76), 05-21 (76) — by astronomy; check the weather when the night is within four days.

2041-05-04astronomy score per night — click a bar for that night2041-06-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-05-04 Sat	89	—	unknown	22:15–02:50 (good, 4.58 h)	50.1° 23:00	6.17	21%	86.7°
2041-05-05 Sun	84	—	unknown	22:15–02:50 (good, 4.58 h)	50.1° 22:55	6.11	29%	74.5°
2041-05-06 Mon	75	—	unknown	22:20–02:45 (good, 4.42 h)	50.1° 22:50	6.05	38%	62.4°
2041-05-07 Tue	60	—	unknown	22:20–02:20 (good, 4.0 h)	50.1° 22:50	6.0	48%	50.5°
2041-05-08 Wed	45	—	unknown	23:25–01:40 (good, 2.25 h)	50.1° 22:45	5.94	57%	38.7°
2041-05-09 Thu	32	—	unknown	22:25–02:55 (marginal, 4.5 h)	50.1° 22:40	5.89	66%	26.8°
2041-05-10 Fri	25	—	unknown	22:25–02:45 (marginal, 4.33 h)	50.1° 22:35	5.83	75%	14.9°
2041-05-11 Sat	19	—	unknown	22:25–02:30 (marginal, 4.08 h)	50.1° 22:30	5.77	83%	3.1°
2041-05-12 Sun	16	—	unknown	22:30–02:20 (marginal, 3.83 h)	50.1° 22:30	5.72	90%	9.8°
2041-05-13 Mon	14	—	unknown	22:30–02:05 (marginal, 3.58 h)	50.1° 22:25	5.67	95%	22.3°
2041-05-14 Tue	18	—	unknown	22:30–02:00 (marginal, 3.5 h)	50.1° 22:20	5.61	99%	35.3°
2041-05-15 Wed	26	—	unknown	22:35–02:10 (marginal, 3.58 h)	50.1° 22:15	5.56	100%	48.5°
2041-05-16 Thu	37	—	unknown	22:35–23:10 (good, 0.58 h)	50.1° 22:15	5.51	99%	62.0°
2041-05-17 Fri	65	—	unknown	22:35–00:55 (good, 2.33 h)	50.1° 22:10	5.45	96%	75.8°
2041-05-18 Sat	73	—	unknown	22:40–01:35 (good, 2.92 h)	50.1° 22:05	5.4	90%	89.7°
2041-05-19 Sun	76	—	unknown	22:40–01:40 (good, 3.0 h)	50.1° 22:00	5.35	82%	103.8°
2041-05-20 Mon	77	—	unknown	22:40–01:45 (good, 3.08 h)	50.1° 21:55	5.3	72%	118.0°
2041-05-21 Tue	76	—	unknown	22:40–01:45 (good, 3.08 h)	50.1° 21:55	5.25	62%	132.2°
2041-05-22 Wed	73	—	unknown	22:45–01:40 (good, 2.92 h)	50.1° 21:50	5.2	50%	146.3°
2041-05-23 Thu	71	—	unknown	22:45–01:35 (good, 2.83 h)	50.1° 21:45	5.16	39%	160.5°
2041-05-24 Fri	69	—	unknown	22:45–01:35 (good, 2.83 h)	50.1° 21:40	5.11	28%	174.4°
2041-05-25 Sat	66	—	unknown	22:50–01:30 (good, 2.67 h)	50.1° 21:35	5.07	18%	171.3°
2041-05-26 Sun	65	—	unknown	22:50–01:25 (good, 2.58 h)	50.1° 21:35	5.02	10%	157.5°
2041-05-27 Mon	63	—	unknown	22:50–01:20 (good, 2.5 h)	50.1° 21:30	4.98	5%	143.8°
2041-05-28 Tue	60	—	unknown	22:55–01:15 (good, 2.33 h)	50.1° 21:25	4.94	1%	130.2°
2041-05-29 Wed	58	—	unknown	22:55–01:15 (good, 2.33 h)	50.1° 21:20	4.9	0%	117.0°
2041-05-30 Thu	57	—	unknown	22:55–01:10 (good, 2.25 h)	50.1° 21:20	4.86	1%	104.0°
2041-05-31 Fri	56	—	unknown	22:55–01:05 (good, 2.17 h)	50.1° 21:15	4.82	4%	91.2°
2041-06-01 Sat	51	—	unknown	23:00–01:00 (good, 2.0 h)	50.1° 21:10	4.78	9%	78.8°
2041-06-02 Sun	47	—	unknown	23:00–01:00 (good, 2.0 h)	50.1° 21:05	4.75	16%	66.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-05-04&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.