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: 01-28 (89), 01-29 (89), 01-30 (89), 01-31 (89), 02-01 (89) — by astronomy; check the weather when the night is within four days.

2027-01-28astronomy score per night — click a bar for that night2027-02-26

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-01-28 Thu	89	—	unknown	19:10–00:45 (good, 5.58 h)	42.9° 21:25	10.89	55%	121.2°
2027-01-29 Fri	89	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:20	10.86	45%	130.4°
2027-01-30 Sat	89	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:20	10.83	36%	138.2°
2027-01-31 Sun	89	—	unknown	19:15–00:35 (good, 5.33 h)	42.9° 21:15	10.8	27%	144.0°
2027-02-01 Mon	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:10	10.77	19%	146.8°
2027-02-02 Tue	89	—	unknown	19:15–00:25 (good, 5.17 h)	42.9° 21:05	10.73	12%	145.9°
2027-02-03 Wed	89	—	unknown	19:15–00:20 (good, 5.08 h)	42.9° 21:05	10.7	7%	141.7°
2027-02-04 Thu	89	—	unknown	19:15–00:20 (good, 5.08 h)	42.9° 21:00	10.66	3%	135.1°
2027-02-05 Fri	89	—	unknown	19:20–00:15 (good, 4.92 h)	42.9° 20:55	10.63	0%	126.9°
2027-02-06 Sat	89	—	unknown	19:20–00:10 (good, 4.83 h)	42.9° 20:50	10.59	0%	117.8°
2027-02-07 Sun	89	—	unknown	19:20–00:05 (good, 4.75 h)	42.9° 20:45	10.56	2%	108.0°
2027-02-08 Mon	89	—	unknown	19:20–00:00 (good, 4.67 h)	42.9° 20:45	10.52	5%	97.8°
2027-02-09 Tue	89	—	unknown	19:25–00:00 (good, 4.58 h)	42.9° 20:40	10.49	10%	87.4°
2027-02-10 Wed	87	—	unknown	19:25–23:55 (good, 4.5 h)	42.9° 20:35	10.45	17%	76.8°
2027-02-11 Thu	81	—	unknown	19:25–23:50 (good, 4.42 h)	42.9° 20:30	10.41	25%	66.3°
2027-02-12 Fri	66	—	unknown	19:25–23:35 (good, 4.17 h)	42.9° 20:25	10.37	35%	56.0°
2027-02-13 Sat	51	—	unknown	19:25–23:15 (good, 3.83 h)	42.9° 20:25	10.33	46%	46.5°
2027-02-14 Sun	35	—	unknown	19:30–00:05 (marginal, 4.58 h)	42.9° 20:20	10.3	57%	38.5°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-01-28&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.