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: 02-24 (73), 02-25 (72), 02-23 (71), 02-26 (70), 02-27 (69) — by astronomy; check the weather when the night is within four days.

2027-02-15astronomy score per night — click a bar for that night2027-03-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-02-15 Mon	22	—	unknown	19:30–23:45 (marginal, 4.25 h)	42.9° 20:15	10.26	68%	33.7°
2027-02-16 Tue	15	—	unknown	19:30–23:20 (marginal, 3.83 h)	42.9° 20:10	10.22	78%	33.8°
2027-02-17 Wed	13	—	unknown	19:30–22:55 (marginal, 3.42 h)	42.9° 20:10	10.18	87%	39.1°
2027-02-18 Thu	15	—	unknown	19:35–22:55 (marginal, 3.33 h)	42.9° 20:05	10.13	94%	48.1°
2027-02-19 Fri	22	—	unknown	19:35–23:05 (marginal, 3.5 h)	42.9° 20:00	10.09	98%	59.0°
2027-02-20 Sat	31	—	unknown	19:35–23:20 (marginal, 3.75 h)	42.9° 19:55	10.05	100%	70.8°
2027-02-21 Sun	43	—	unknown	19:35–21:25 (good, 1.83 h)	42.9° 19:50	10.01	99%	82.9°
2027-02-22 Mon	65	—	unknown	19:40–22:40 (good, 3.0 h)	42.9° 19:50	9.97	95%	94.9°
2027-02-23 Tue	71	—	unknown	19:40–22:45 (good, 3.08 h)	42.9° 19:45	9.92	89%	106.5°
2027-02-24 Wed	73	—	unknown	19:40–22:50 (good, 3.17 h)	42.9° 19:40	9.88	81%	117.4°
2027-02-25 Thu	72	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:35	9.84	72%	127.3°
2027-02-26 Fri	70	—	unknown	19:40–22:50 (good, 3.17 h)	42.9° 19:30	9.79	62%	135.8°
2027-02-27 Sat	69	—	unknown	19:45–22:45 (good, 3.0 h)	42.9° 19:30	9.75	53%	142.5°
2027-02-28 Sun	67	—	unknown	19:45–22:45 (good, 3.0 h)	42.9° 19:25	9.7	43%	146.3°
2027-03-01 Mon	65	—	unknown	19:45–22:40 (good, 2.92 h)	42.9° 19:20	9.66	34%	146.6°
2027-03-02 Tue	63	—	unknown	19:45–22:35 (good, 2.83 h)	42.9° 19:15	9.61	25%	143.3°
2027-03-03 Wed	62	—	unknown	19:50–22:30 (good, 2.67 h)	42.9° 19:15	9.57	18%	137.3°
2027-03-04 Thu	60	—	unknown	19:50–22:30 (good, 2.67 h)	42.9° 19:10	9.52	11%	129.5°
2027-03-05 Fri	58	—	unknown	19:50–22:25 (good, 2.58 h)	42.9° 19:05	9.47	6%	120.5°
2027-03-06 Sat	57	—	unknown	19:50–22:20 (good, 2.5 h)	42.9° 19:00	9.43	2%	110.9°
2027-03-07 Sun	54	—	unknown	19:55–22:15 (good, 2.33 h)	42.9° 18:55	9.38	0%	100.7°
2027-03-08 Mon	53	—	unknown	19:55–22:10 (good, 2.25 h)	42.9° 18:55	9.33	0%	90.2°
2027-03-09 Tue	51	—	unknown	19:55–22:10 (good, 2.25 h)	42.9° 18:50	9.28	3%	79.5°
2027-03-10 Wed	48	—	unknown	19:55–22:05 (good, 2.17 h)	42.9° 18:45	9.23	7%	68.8°
2027-03-11 Thu	43	—	unknown	20:00–22:00 (good, 2.0 h)	42.9° 18:40	9.19	13%	58.3°
2027-03-12 Fri	36	—	unknown	20:00–21:45 (good, 1.75 h)	42.9° 18:35	9.14	21%	48.5°
2027-03-13 Sat	30	—	unknown	20:00–21:35 (good, 1.58 h)	42.9° 18:35	9.09	31%	40.1°
2027-03-14 Sun	22	—	unknown	20:00–20:30 (good, 0.5 h)	42.9° 18:30	9.04	42%	34.4°
2027-03-15 Mon	15	—	unknown	20:00–22:05 (marginal, 2.08 h)	42.9° 18:25	8.99	53%	33.2°
2027-03-16 Tue	11	—	unknown	20:05–21:50 (marginal, 1.75 h)	42.9° 18:20	8.94	64%	37.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-02-15&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.