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: 11-22 (89), 11-23 (89), 11-24 (89), 11-25 (89), 11-26 (89) — by astronomy; check the weather when the night is within four days.

2027-11-21astronomy score per night — click a bar for that night2027-12-20

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-11-21 Sun	87	—	unknown	22:40–04:55 (good, 6.25 h)	42.9° 01:55	11.11	40%	78.0°
2027-11-22 Mon	89	—	unknown	22:35–05:00 (good, 6.42 h)	42.9° 01:50	11.14	29%	89.8°
2027-11-23 Tue	89	—	unknown	22:35–05:00 (good, 6.42 h)	42.9° 01:45	11.16	20%	101.5°
2027-11-24 Wed	89	—	unknown	22:30–05:00 (good, 6.5 h)	42.9° 01:45	11.19	12%	113.0°
2027-11-25 Thu	89	—	unknown	22:25–05:00 (good, 6.58 h)	42.9° 01:40	11.21	6%	123.8°
2027-11-26 Fri	89	—	unknown	22:20–04:55 (good, 6.58 h)	42.9° 01:35	11.23	2%	133.6°
2027-11-27 Sat	89	—	unknown	22:15–04:50 (good, 6.58 h)	42.9° 01:30	11.25	0%	141.6°
2027-11-28 Sun	89	—	unknown	22:15–04:45 (good, 6.5 h)	42.9° 01:25	11.27	1%	146.8°
2027-11-29 Mon	89	—	unknown	22:10–04:40 (good, 6.5 h)	42.9° 01:25	11.29	3%	147.9°
2027-11-30 Tue	89	—	unknown	22:05–04:40 (good, 6.58 h)	42.9° 01:20	11.31	8%	144.9°
2027-12-01 Wed	89	—	unknown	22:00–04:35 (good, 6.58 h)	42.9° 01:15	11.33	14%	138.8°
2027-12-02 Thu	89	—	unknown	21:55–04:30 (good, 6.58 h)	42.9° 01:10	11.34	21%	130.9°
2027-12-03 Fri	89	—	unknown	21:55–04:25 (good, 6.5 h)	42.9° 01:05	11.36	29%	122.0°
2027-12-04 Sat	89	—	unknown	21:55–04:25 (good, 6.5 h)	42.9° 01:05	11.38	38%	112.5°
2027-12-05 Sun	89	—	unknown	21:55–04:20 (good, 6.42 h)	42.9° 01:00	11.39	47%	102.6°
2027-12-06 Mon	89	—	unknown	22:00–04:15 (good, 6.25 h)	42.9° 00:55	11.4	57%	92.5°
2027-12-07 Tue	88	—	unknown	22:05–04:10 (good, 6.08 h)	42.9° 00:50	11.42	66%	82.2°
2027-12-08 Wed	84	—	unknown	23:25–04:05 (good, 4.67 h)	42.9° 00:50	11.43	75%	71.7°
2027-12-09 Thu	58	—	unknown	04:00–04:05 (good, 0.08 h)	42.9° 00:45	11.44	83%	61.3°
2027-12-10 Fri	38	—	unknown	21:40–04:25 (marginal, 6.75 h)	42.9° 00:40	11.45	90%	51.1°
2027-12-11 Sat	23	—	unknown	23:45–04:00 (marginal, 4.25 h)	42.9° 00:35	11.46	96%	41.9°
2027-12-12 Sun	13	—	unknown	—	42.9° 00:30	11.47	99%	34.8°
2027-12-13 Mon	9	—	unknown	—	42.9° 00:30	11.48	100%	31.9°
2027-12-14 Tue	14	—	unknown	21:40–21:50 (marginal, 0.17 h)	42.9° 00:25	11.48	98%	34.6°
2027-12-15 Wed	25	—	unknown	20:55–02:15 (marginal, 5.33 h)	42.9° 00:20	11.49	93%	42.0°
2027-12-16 Thu	43	—	unknown	20:35–03:30 (marginal, 6.92 h)	42.9° 00:15	11.5	86%	52.0°
2027-12-17 Fri	77	—	unknown	21:00–00:20 (good, 3.33 h)	42.9° 00:10	11.5	77%	63.4°
2027-12-18 Sat	86	—	unknown	20:55–02:40 (good, 5.75 h)	42.9° 00:10	11.5	66%	75.2°
2027-12-19 Sun	89	—	unknown	20:50–03:05 (good, 6.25 h)	42.9° 00:05	11.51	55%	87.2°
2027-12-20 Mon	89	—	unknown	20:45–03:10 (good, 6.42 h)	42.9° 00:00	11.51	44%	98.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-11-21&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.