ο	15h 20m 08.64s	15h 20.144m	233.0
η	15h 23m 12.23s	15h 23.204m	233.8
θ	15h 32m 55.80s	15h 32.930m	236.3
Gemma	15h 34m 41.19s	15h 34.687m	236.7
μ	15h 35m 14.90s	15h 35.248m	236.8
ζ	15h 39m 22.68s	15h 39.378m	237.9
π	15h 43m 59.32s	15h 43.989m	239.1
κ	15h 51m 13.94s	15h 51.232m	240.9
λ	15h 55m 47.57s	15h 55.793m	242.1
ρ	16h 01m 02.80s	16h 01.047m	243.4
ι	16h 01m 26.59s	16h 01.443m	243.5

Adding 3 + 7 stars to the previous 1 + 4 results in 15 stars. Although the last of them to rise, ι, is exactly at the line for 16h. Day 243½ corresponds to 243½ / 365¼ * 24h = 16h beyond March 21.

16th hour:
Nekkar	β Bootis	3.49	40° 35′ N	15h 00m	228.3	636.3
	π Lupi	3.91	47° 03′ S	15h 02m	228.9	636.9
Zuben Hakrabim	ν Librae	5.19	16° 04′ S	15h 04m	229.3	637.3
	λ Lupi	4.07	45° 17′ S	15h 06m	229.9	637.9
	κ Lupi	3.88	48° 44′ S	15h 10m	230.7	638.7
	ζ Lupi	3.41	52° 06′ S	15h 10m	230.8	638.8
Zuben Elschemali	β Librae	2.61	09° 12′ S	15h 14m	231.8	639.8
	μ Lupi	4.27	47° 53′ S	15h 16m	232.3	640.3
	ο Cor. Borealis	5.51	29° 37′ N	15h 19m	233.0	641.0
	δ Lupi	3.22	40° 39′ S	15h 19m	233.1	641.1
	φ¹ Lupi	3.57	36° 16′ S	15h 19m	233.2	642.2
	ν² Lupi	5.65	48° 19′ S
	ν¹ Lupi	4.99	47° 56′ S	15h 20m	233.3	641.3
	ε Lupi	3.37	44° 41′ S	15h 20m	233.4	641.4
	φ² Lupi	4.54	36° 52′ S	15h 21m	233.5	641.5
Pherkad	γ Ursa Minoris	3.00	72° 01′ N	15h 21m	233.6	641.6
	η Cor. Borealis	4.99	30° 17′ N	15h 22m	233.8	641.8
	υ Lupi	5.36	39° 43′ S	15h 22m	233.9	641.9
Alkalurops	μ Bootis	4.31	37° 33′ N	15h 23m	234.1	642.1
Nusakan	β Cor. Borealis	3.66	29° 06′ N	15h 26m	235.0	643.0
	θ Cor. Borealis	4.14	31° 22′ N	15h 32m	236.3	644.3
	γ Lupi	2.80	41° 10′ S	15h 33m	236.6	644.6
Gemma	α Cor. Borealis	2.22	26° 53′ N	15h 33m	236.7	644.7
Zuben Elakrab	γ Librae	3.91	14° 37′ S
	μ Cor. Borealis	5.14	39° 01′ N	15h 34m	236.8	644.8
	ω Lupi	4.34	42° 34′ S	15h 36m	237.3	645.3
	ψ¹ Lupi	4.66	34° 25′ S	15h 37m	237.7	645.7
	ζ Cor. Borealis	4.64	36° 38′ N	15h 38m	237.9	645.9
	ψ² Lupi	4.54	36° 52′ S	15h 40m	238.5	646.5
	γ Cor. Borealis	3.81	26° 18′ N	15h 41m	238.7	646.7
Unuk Elhaia	α Serpentis	2.63	06° 15′ N	15h 42m	238.9	646.9
	π Cor. Borealis	5.57	32° 31′ N	15h 43m	239.1	647.1
	δ Cor. Borealis	4.59	26° 04′ N	15h 48m	240.5	648.5
	χ Lupi	3.97	33° 38′ S	15h 49m	240.6	648.6
	κ Cor. Borealis	4.79	35° 39′ N	15h 50m	240.9	648.9
	ξ Lupi	5.14	33° 58′ S	15h 54m	242.1	650.1
	λ Cor. Borealis	5.43	37° 57′ N
	ε Cor. Borealis	4.14	26° 53′ N	15h 56m	242.5	650.5
Dschubba	δ Scorpii	2.29	22° 19′ S	15h 57m	242.7	650.7
	η Lupi	3.42	38° 24′ S	15h 58m	242.9	650.9
	ρ Cor. Borealis	5.39	33° 18′ N	16h 00m	243.4	651.4
	ι Cor. Borealis	4.98	29° 51′ N	16h 00m	243.5	651.5
	θ Lupi	4.22	36° 48′ S	16h 04m	244.5	652.5