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: 05-28 (49), 05-29 (39), 06-09 (39), 06-10 (38), 06-08 (37) — by astronomy; check the weather when the night is within four days.

2039-05-28astronomy score per night — click a bar for that night2039-06-26

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-05-28 Sat	49	—	unknown	22:50–01:10 (good, 2.33 h)	50.1° 21:30	4.96	28%	53.8°
2039-05-29 Sun	39	—	unknown	22:55–01:00 (good, 2.08 h)	50.1° 21:25	4.92	38%	41.3°
2039-05-30 Mon	29	—	unknown	22:55–00:40 (good, 1.75 h)	50.1° 21:20	4.88	48%	28.5°
2039-05-31 Tue	22	—	unknown	22:55–01:35 (marginal, 2.67 h)	50.1° 21:15	4.84	59%	15.3°
2039-06-01 Wed	16	—	unknown	22:55–01:20 (marginal, 2.42 h)	50.1° 21:10	4.8	69%	1.6°
2039-06-02 Thu	12	—	unknown	23:00–01:05 (marginal, 2.08 h)	50.1° 21:10	4.77	79%	12.5°
2039-06-03 Fri	9	—	unknown	23:00–00:50 (marginal, 1.83 h)	50.1° 21:05	4.73	88%	27.0°
2039-06-04 Sat	11	—	unknown	23:00–00:50 (marginal, 1.83 h)	50.1° 21:00	4.7	95%	41.9°
2039-06-05 Sun	15	—	unknown	23:00–00:55 (marginal, 1.92 h)	50.1° 20:55	4.67	99%	57.1°
2039-06-06 Mon	20	—	unknown	23:05–01:05 (marginal, 2.0 h)	50.1° 20:50	4.64	100%	72.3°
2039-06-07 Tue	26	—	unknown	23:05–00:10 (good, 1.08 h)	50.1° 20:50	4.61	98%	87.5°
2039-06-08 Wed	37	—	unknown	23:05–00:20 (good, 1.25 h)	50.1° 20:45	4.58	93%	102.5°
2039-06-09 Thu	39	—	unknown	23:05–00:25 (good, 1.33 h)	50.1° 20:40	4.56	86%	117.0°
2039-06-10 Fri	38	—	unknown	23:05–00:30 (good, 1.42 h)	50.1° 20:35	4.54	77%	131.2°
2039-06-11 Sat	35	—	unknown	23:10–00:25 (good, 1.25 h)	50.1° 20:30	4.52	67%	144.8°
2039-06-12 Sun	35	—	unknown	23:10–00:20 (good, 1.17 h)	50.1° 20:30	4.5	57%	158.1°
2039-06-13 Mon	33	—	unknown	23:10–00:15 (good, 1.08 h)	50.1° 20:25	4.48	47%	170.9°
2039-06-14 Tue	31	—	unknown	23:10–00:10 (good, 1.0 h)	50.1° 20:20	4.47	37%	176.6°
2039-06-15 Wed	29	—	unknown	23:10–00:10 (good, 1.0 h)	50.1° 20:15	4.45	28%	164.4°
2039-06-16 Thu	29	—	unknown	23:10–00:05 (good, 0.92 h)	50.1° 20:15	4.44	19%	152.4°
2039-06-17 Fri	27	—	unknown	23:10–00:00 (good, 0.83 h)	50.1° 20:10	4.44	12%	140.5°
2039-06-18 Sat	26	—	unknown	23:10–23:55 (good, 0.75 h)	50.1° 20:05	4.43	7%	128.7°
2039-06-19 Sun	24	—	unknown	23:10–23:55 (good, 0.75 h)	50.1° 20:00	4.42	3%	116.8°
2039-06-20 Mon	22	—	unknown	23:15–23:50 (good, 0.58 h)	50.1° 19:55	4.42	1%	105.0°
2039-06-21 Tue	21	—	unknown	23:15–23:45 (good, 0.5 h)	50.1° 19:55	4.42	0%	93.1°
2039-06-22 Wed	19	—	unknown	23:15–23:40 (good, 0.42 h)	50.1° 19:50	4.42	1%	81.1°
2039-06-23 Thu	17	—	unknown	23:15–23:35 (good, 0.33 h)	50.1° 19:45	4.43	4%	69.0°
2039-06-24 Fri	16	—	unknown	23:15–23:35 (good, 0.33 h)	50.1° 19:40	4.43	10%	56.7°
2039-06-25 Sat	13	—	unknown	23:15–23:25 (good, 0.17 h)	50.1° 19:35	4.44	16%	44.3°
2039-06-26 Sun	10	—	unknown	22:20–23:55 (marginal, 1.58 h)	50.1° 19:35	4.45	24%	31.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-05-28&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.