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: 05-23 (68), 05-24 (68), 05-25 (67), 05-26 (66), 05-22 (65) — by astronomy; check the weather when the night is within four days.

2046-05-21astronomy score per night — click a bar for that night2046-06-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2046-05-21 Mon	60	—	unknown	22:40–00:50 (good, 2.17 h)	50.1° 21:55	5.26	96%	78.6°
2046-05-22 Tue	65	—	unknown	22:45–01:20 (good, 2.58 h)	50.1° 21:50	5.21	91%	91.8°
2046-05-23 Wed	68	—	unknown	22:45–01:25 (good, 2.67 h)	50.1° 21:45	5.17	84%	104.6°
2046-05-24 Thu	68	—	unknown	22:45–01:25 (good, 2.67 h)	50.1° 21:40	5.12	76%	117.0°
2046-05-25 Fri	67	—	unknown	22:50–01:25 (good, 2.58 h)	50.1° 21:40	5.07	67%	129.1°
2046-05-26 Sat	66	—	unknown	22:50–01:25 (good, 2.58 h)	50.1° 21:35	5.03	57%	140.9°
2046-05-27 Sun	63	—	unknown	22:50–01:20 (good, 2.5 h)	50.1° 21:30	4.99	48%	152.3°
2046-05-28 Mon	62	—	unknown	22:50–01:20 (good, 2.5 h)	50.1° 21:25	4.94	39%	162.9°
2046-05-29 Tue	59	—	unknown	22:55–01:15 (good, 2.33 h)	50.1° 21:25	4.9	30%	170.5°
2046-05-30 Wed	58	—	unknown	22:55–01:10 (good, 2.25 h)	50.1° 21:20	4.86	21%	166.9°
2046-05-31 Thu	56	—	unknown	22:55–01:05 (good, 2.17 h)	50.1° 21:15	4.83	14%	156.8°
2046-06-01 Fri	53	—	unknown	23:00–01:05 (good, 2.08 h)	50.1° 21:10	4.79	8%	145.2°
2046-06-02 Sat	51	—	unknown	23:00–01:00 (good, 2.0 h)	50.1° 21:05	4.75	3%	133.0°
2046-06-03 Sun	50	—	unknown	23:00–00:55 (good, 1.92 h)	50.1° 21:05	4.72	1%	120.4°
2046-06-04 Mon	48	—	unknown	23:00–00:50 (good, 1.83 h)	50.1° 21:00	4.69	0%	107.4°
2046-06-05 Tue	47	—	unknown	23:00–00:45 (good, 1.75 h)	50.1° 20:55	4.66	2%	94.2°
2046-06-06 Wed	44	—	unknown	23:05–00:45 (good, 1.67 h)	50.1° 20:50	4.63	6%	80.8°
2046-06-07 Thu	40	—	unknown	23:05–00:40 (good, 1.58 h)	50.1° 20:45	4.6	12%	67.1°
2046-06-08 Fri	36	—	unknown	23:05–00:35 (good, 1.5 h)	50.1° 20:45	4.58	21%	53.4°
2046-06-09 Sat	30	—	unknown	23:05–00:20 (good, 1.25 h)	50.1° 20:40	4.55	31%	39.7°
2046-06-10 Sun	23	—	unknown	23:05–00:05 (good, 1.0 h)	50.1° 20:35	4.53	42%	26.2°
2046-06-11 Mon	18	—	unknown	23:10–00:50 (marginal, 1.67 h)	50.1° 20:30	4.51	53%	13.9°
2046-06-12 Tue	14	—	unknown	23:10–00:40 (marginal, 1.5 h)	50.1° 20:30	4.49	65%	10.0°
2046-06-13 Wed	11	—	unknown	23:10–00:30 (marginal, 1.33 h)	50.1° 20:25	4.48	75%	20.1°
2046-06-14 Thu	9	—	unknown	23:10–00:20 (marginal, 1.17 h)	50.1° 20:20	4.46	84%	33.2°
2046-06-15 Fri	9	—	unknown	23:10–00:20 (marginal, 1.17 h)	50.1° 20:15	4.45	92%	46.7°
2046-06-16 Sat	10	—	unknown	23:10–00:20 (marginal, 1.17 h)	50.1° 20:10	4.44	97%	60.3°
2046-06-17 Sun	13	—	unknown	23:10–00:20 (marginal, 1.17 h)	50.1° 20:10	4.43	99%	73.7°
2046-06-18 Mon	15	—	unknown	23:10–23:25 (good, 0.25 h)	50.1° 20:05	4.43	100%	87.0°
2046-06-19 Tue	17	—	unknown	23:10–23:35 (good, 0.42 h)	50.1° 20:00	4.42	98%	99.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2046-05-21&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.