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: 03-20 (93), 03-21 (93), 03-22 (93), 03-23 (93), 04-04 (93) — by astronomy; check the weather when the night is within four days.

2037-03-20astronomy score per night — click a bar for that night2037-04-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-03-20 Fri	93	—	unknown	21:10–04:50 (good, 7.67 h)	50.2° 00:55	8.7	14%	141.2°
2037-03-21 Sat	93	—	unknown	21:10–04:45 (good, 7.58 h)	50.2° 00:55	8.65	22%	128.7°
2037-03-22 Sun	93	—	unknown	21:05–04:40 (good, 7.58 h)	50.2° 00:50	8.6	31%	115.9°
2037-03-23 Mon	93	—	unknown	21:05–04:35 (good, 7.5 h)	50.2° 00:45	8.55	41%	102.9°
2037-03-24 Tue	91	—	unknown	21:10–04:35 (good, 7.42 h)	50.2° 00:40	8.5	52%	89.5°
2037-03-25 Wed	86	—	unknown	21:40–04:30 (good, 6.83 h)	50.2° 00:35	8.44	63%	75.8°
2037-03-26 Thu	81	—	unknown	23:50–04:25 (good, 4.58 h)	50.2° 00:35	8.39	73%	61.6°
2037-03-27 Fri	53	—	unknown	20:50–04:40 (marginal, 7.83 h)	50.2° 00:30	8.34	83%	47.1°
2037-03-28 Sat	31	—	unknown	22:50–05:30 (marginal, 5.67 h)	50.2° 00:25	8.28	91%	32.2°
2037-03-29 Sun	23	—	unknown	01:55–05:15 (marginal, 3.33 h)	50.2° 01:20	8.23	97%	17.2°
2037-03-30 Mon	20	—	unknown	03:15–04:55 (marginal, 1.67 h)	50.1° 01:15	8.17	100%	2.1°
2037-03-31 Tue	24	—	unknown	21:25–01:55 (marginal, 4.5 h)	50.2° 01:15	8.12	99%	13.0°
2037-04-01 Wed	35	—	unknown	21:25–04:40 (marginal, 7.25 h)	50.2° 01:10	8.06	96%	27.7°
2037-04-02 Thu	84	—	unknown	21:25–22:30 (good, 1.08 h)	50.2° 01:05	8.01	91%	42.1°
2037-04-03 Fri	90	—	unknown	21:30–02:00 (good, 4.5 h)	50.2° 01:00	7.95	84%	56.0°
2037-04-04 Sat	93	—	unknown	21:30–03:55 (good, 6.42 h)	50.2° 01:00	7.9	75%	69.5°
2037-04-05 Sun	93	—	unknown	21:30–04:25 (good, 6.92 h)	50.2° 00:55	7.84	65%	82.6°
2037-04-06 Mon	93	—	unknown	21:30–04:30 (good, 7.0 h)	50.2° 00:50	7.79	55%	95.2°
2037-04-07 Tue	93	—	unknown	21:35–04:30 (good, 6.92 h)	50.2° 00:45	7.73	46%	107.5°
2037-04-08 Wed	93	—	unknown	21:35–04:30 (good, 6.92 h)	50.2° 00:40	7.67	36%	119.6°
2037-04-09 Thu	93	—	unknown	21:35–04:30 (good, 6.92 h)	50.2° 00:40	7.62	27%	131.5°
2037-04-10 Fri	93	—	unknown	21:40–04:25 (good, 6.75 h)	50.2° 00:35	7.56	19%	143.3°
2037-04-11 Sat	93	—	unknown	21:40–04:20 (good, 6.67 h)	50.2° 00:30	7.5	12%	155.1°
2037-04-12 Sun	93	—	unknown	21:40–04:20 (good, 6.67 h)	50.2° 00:25	7.45	7%	167.0°
2037-04-13 Mon	93	—	unknown	21:40–04:15 (good, 6.58 h)	50.1° 00:20	7.39	3%	178.9°
2037-04-14 Tue	93	—	unknown	21:45–04:10 (good, 6.42 h)	50.2° 00:20	7.33	1%	169.0°
2037-04-15 Wed	93	—	unknown	21:45–04:05 (good, 6.33 h)	50.2° 00:15	7.27	0%	156.8°
2037-04-16 Thu	93	—	unknown	21:45–04:00 (good, 6.25 h)	50.2° 00:10	7.22	2%	144.3°
2037-04-17 Fri	93	—	unknown	21:50–04:00 (good, 6.17 h)	50.2° 00:05	7.16	5%	131.7°
2037-04-18 Sat	93	—	unknown	21:50–03:55 (good, 6.08 h)	50.2° 00:05	7.1	11%	118.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-03-20&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.