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: 04-07 (93), 04-08 (93), 04-09 (93), 04-10 (93), 04-23 (93) — by astronomy; check the weather when the night is within four days.

2027-04-07astronomy score per night — click a bar for that night2027-05-06

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-04-07 Wed	93	—	unknown	21:30–04:40 (good, 7.17 h)	50.2° 00:50	7.76	1%	154.5°
2027-04-08 Thu	93	—	unknown	21:35–04:35 (good, 7.0 h)	50.2° 00:45	7.71	5%	141.4°
2027-04-09 Fri	93	—	unknown	21:35–04:30 (good, 6.92 h)	50.2° 00:40	7.65	10%	127.9°
2027-04-10 Sat	93	—	unknown	21:35–04:30 (good, 6.92 h)	50.2° 00:35	7.59	18%	114.2°
2027-04-11 Sun	92	—	unknown	21:40–04:25 (good, 6.75 h)	50.2° 00:30	7.54	28%	100.3°
2027-04-12 Mon	89	—	unknown	21:40–04:20 (good, 6.67 h)	50.2° 00:30	7.48	38%	86.3°
2027-04-13 Tue	84	—	unknown	21:40–04:15 (good, 6.58 h)	50.2° 00:25	7.42	50%	72.3°
2027-04-14 Wed	77	—	unknown	22:40–04:10 (good, 5.5 h)	50.2° 00:20	7.36	61%	58.4°
2027-04-15 Thu	56	—	unknown	21:45–04:35 (marginal, 6.83 h)	50.2° 00:15	7.31	72%	44.5°
2027-04-16 Fri	36	—	unknown	21:45–04:25 (marginal, 6.67 h)	50.2° 00:10	7.25	81%	30.9°
2027-04-17 Sat	28	—	unknown	21:45–04:15 (marginal, 6.5 h)	50.2° 00:10	7.19	89%	17.9°
2027-04-18 Sun	23	—	unknown	21:50–04:00 (marginal, 6.17 h)	50.2° 00:05	7.13	95%	8.7°
2027-04-19 Mon	22	—	unknown	21:50–03:45 (marginal, 5.92 h)	50.2° 00:00	7.08	99%	14.4°
2027-04-20 Tue	26	—	unknown	21:50–03:40 (marginal, 5.83 h)	50.2° 23:55	7.02	100%	26.4°
2027-04-21 Wed	39	—	unknown	21:55–03:45 (marginal, 5.83 h)	50.2° 23:55	6.96	99%	39.1°
2027-04-22 Thu	85	—	unknown	21:55–23:30 (good, 1.58 h)	50.2° 23:50	6.9	96%	51.6°
2027-04-23 Fri	93	—	unknown	21:55–01:45 (good, 3.83 h)	50.2° 23:45	6.84	90%	64.0°
2027-04-24 Sat	93	—	unknown	22:00–03:00 (good, 5.0 h)	50.2° 23:40	6.78	84%	76.2°
2027-04-25 Sun	93	—	unknown	22:00–03:10 (good, 5.17 h)	50.2° 23:35	6.73	76%	88.2°
2027-04-26 Mon	93	—	unknown	22:00–03:15 (good, 5.25 h)	50.2° 23:35	6.67	68%	100.0°
2027-04-27 Tue	93	—	unknown	22:05–03:15 (good, 5.17 h)	50.2° 23:30	6.61	59%	111.7°
2027-04-28 Wed	93	—	unknown	22:05–03:15 (good, 5.17 h)	50.2° 23:25	6.55	49%	123.4°
2027-04-29 Thu	93	—	unknown	22:05–03:15 (good, 5.17 h)	50.2° 23:20	6.49	40%	135.1°
2027-04-30 Fri	93	—	unknown	22:05–03:10 (good, 5.08 h)	50.2° 23:15	6.43	31%	146.8°
2027-05-01 Sat	93	—	unknown	22:10–03:05 (good, 4.92 h)	50.2° 23:15	6.38	22%	158.5°
2027-05-02 Sun	93	—	unknown	22:10–03:00 (good, 4.83 h)	50.2° 23:10	6.32	14%	168.8°
2027-05-03 Mon	93	—	unknown	22:10–03:00 (good, 4.83 h)	50.2° 23:05	6.26	8%	169.7°
2027-05-04 Tue	93	—	unknown	22:15–02:55 (good, 4.67 h)	50.2° 23:00	6.2	3%	159.1°
2027-05-05 Wed	93	—	unknown	22:15–02:50 (good, 4.58 h)	50.2° 23:00	6.15	0%	146.2°
2027-05-06 Thu	93	—	unknown	22:15–02:45 (good, 4.5 h)	50.2° 22:55	6.09	0%	132.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-04-07&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.