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 Great Orion Nebula: 02-21 (80), 02-22 (78), 02-23 (76), 02-24 (74), 02-25 (72) — by astronomy; check the weather when the night is within four days.

2028-02-21astronomy score per night — click a bar for that night2028-03-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-02-21 Mon	80	—	unknown	19:35–23:10 (good, 3.58 h)	42.9° 19:55	10.02	10%	137.6°
2028-02-22 Tue	78	—	unknown	19:35–23:10 (good, 3.58 h)	42.9° 19:50	9.98	6%	129.5°
2028-02-23 Wed	76	—	unknown	19:40–23:05 (good, 3.42 h)	42.9° 19:45	9.93	2%	120.5°
2028-02-24 Thu	74	—	unknown	19:40–23:00 (good, 3.33 h)	42.9° 19:40	9.89	0%	110.9°
2028-02-25 Fri	72	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:35	9.85	0%	101.1°
2028-02-26 Sat	71	—	unknown	19:40–22:50 (good, 3.17 h)	42.9° 19:35	9.8	2%	91.0°
2028-02-27 Sun	68	—	unknown	19:45–22:50 (good, 3.08 h)	42.9° 19:30	9.76	6%	80.9°
2028-02-28 Mon	64	—	unknown	19:45–22:45 (good, 3.0 h)	42.9° 19:25	9.71	11%	70.7°
2028-02-29 Tue	57	—	unknown	19:45–22:40 (good, 2.92 h)	42.9° 19:20	9.67	18%	60.8°
2028-03-01 Wed	49	—	unknown	19:45–22:25 (good, 2.67 h)	42.9° 19:20	9.62	26%	51.3°
2028-03-02 Thu	39	—	unknown	19:50–22:10 (good, 2.33 h)	42.9° 19:15	9.58	35%	42.6°
2028-03-03 Fri	29	—	unknown	19:50–23:00 (marginal, 3.17 h)	42.9° 19:10	9.53	45%	35.7°
2028-03-04 Sat	20	—	unknown	19:50–22:45 (marginal, 2.92 h)	42.9° 19:05	9.48	56%	32.0°
2028-03-05 Sun	14	—	unknown	19:50–22:25 (marginal, 2.58 h)	42.9° 19:00	9.44	67%	33.2°
2028-03-06 Mon	11	—	unknown	19:55–22:10 (marginal, 2.25 h)	42.9° 19:00	9.39	77%	39.2°
2028-03-07 Tue	11	—	unknown	19:55–22:00 (marginal, 2.08 h)	42.9° 18:55	9.34	86%	48.5°
2028-03-08 Wed	14	—	unknown	19:55–22:05 (marginal, 2.17 h)	42.9° 18:50	9.29	93%	59.8°
2028-03-09 Thu	18	—	unknown	19:55–22:15 (marginal, 2.33 h)	42.9° 18:45	9.25	98%	72.2°
2028-03-10 Fri	24	—	unknown	19:55–20:30 (good, 0.58 h)	42.9° 18:40	9.2	100%	85.0°
2028-03-11 Sat	31	—	unknown	20:00–21:30 (good, 1.5 h)	42.9° 18:40	9.15	99%	97.8°
2028-03-12 Sun	42	—	unknown	20:00–21:40 (good, 1.67 h)	42.9° 18:35	9.1	95%	110.3°
2028-03-13 Mon	43	—	unknown	20:00–21:50 (good, 1.83 h)	42.9° 18:30	9.05	88%	122.0°
2028-03-14 Tue	41	—	unknown	20:00–21:45 (good, 1.75 h)	42.9° 18:25	9.0	80%	132.5°
2028-03-15 Wed	39	—	unknown	20:05–21:40 (good, 1.58 h)	42.9° 18:25	8.95	70%	141.1°
2028-03-16 Thu	38	—	unknown	20:05–21:40 (good, 1.58 h)	42.9° 18:20	8.9	60%	146.7°
2028-03-17 Fri	36	—	unknown	20:05–21:35 (good, 1.5 h)	42.9° 18:15	8.85	50%	148.2°
2028-03-18 Sat	34	—	unknown	20:05–21:30 (good, 1.42 h)	42.9° 18:10	8.8	41%	145.5°
2028-03-19 Sun	32	—	unknown	20:10–21:25 (good, 1.25 h)	42.9° 18:05	8.75	31%	139.6°
2028-03-20 Mon	31	—	unknown	20:10–21:20 (good, 1.17 h)	42.9° 18:05	8.7	23%	131.9°
2028-03-21 Tue	29	—	unknown	20:10–21:20 (good, 1.17 h)	42.9° 18:00	8.64	16%	123.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-02-21&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.