17252-4512 B 1856 (HD 157388)

17^h 25^m 09.52^s -45° 11' 43.1" P.A. 140.00 sep 1.6 mag 10.57,10.94 Sp A3/5IV/V

Coord 2000	17252-4512	Discov num	B 1856	Comp		Coord arcsec 2000	17 25 09.52 -45 11 43.1
Date first	1930	Date last	1991	Obs	3
Pa first	143	Pa last	140.2	P.A. Now (θ)	140.2°
Sep first	1.6	Sep last	1.586	Sep. Now (ρ)	1.586"
Mag pri	10.57	Mag sec	10.94	delta mag (ΔM)	0.37	Spectral class	A3/5IV/V (white)
Pri motion ra	+003	Sec motion ra	+003
Pri motion dec	-002	Sec motion dec	-002
Notes

Nature of this double is uncertain.

OTHER CATALOGS AND DESIGNATIONS

Name	HD 157388		Constellation	Scorpius		SAO	227930		Tycho2	8341-00186-1
Gaia DR2	5952064119447224448		HD	157388		DM	CP-45 8549

WDS 17252-4512 B 1856 (HD 157388) : NOTES

No records found.

REFERENCES

refcode	metd	author	reference
B__1921a	orb -	van den Bos, W.H.	1921MNRAS..81..474V
B__1921a		MNRAS 81, 474, 1921
B__1921b	orb -	van den Bos, W.H.	.
B__1921b		Proc. Amsterdam Acad. 30, 72, 1921
B__1923a	Po j	van den Bos, W.H.	1923BAN.....1..193V
B__1923a		BAN 1, 193, 1923
B__1923b	orb -	van den Bos, W.H.	1923BAN.....2...25V
B__1923b		BAN 2, 25, 1923
B__1923c	orb -	van den Bos, W.H.	1923BAN.....2...29V
B__1923c		BAN 2, 29, 1923
B__1925a	Ma j	van den Bos, W.H.	1925AnLei..143...1V
B__1925a		Ann. Leiden Obs. 14, Pt.3, 1925
B__1925b	Ma j	van den Bos, W.H.	1925BAN.....2..197V
B__1925b	+Po	BAN 2, 197, 1925
B__1926a	orb -	van den Bos, W.H.	1926BAN.....3..127V
B__1926a		BAN 3, 127, 1926
B__1926b	orb -	van den Bos, W.H.	1926BAN.....3..128V
B__1926b		BAN 3, 128, 1926
B__1927a	orb -	van den Bos, W.H.	1927BAN.....3..261V
B__1927a		BAN 3, 261, 1927
B__1927b	-	van den Bos, W.H.	1927BAN.....4...45V
B__1927b		BAN 4, 45, 1927
B__1927b		(4th list of new southern double stars; precise measures in later references)
B__1927c	Ma -	van den Bos, W.H.	1927BAN.....4..109V
B__1927c		BAN 4, 109, 1927
B__1927c		(5th list of new southern double stars; precise measures in later references)
B__1927D	Ma -	van den Bos, W.H.	1927sdsc.book......
B__1927D		cited in SDS (Southern Double Star Cat.), 1927
B__1928a	Ma -	van den Bos, W.H.	1928BAN.....4..235V
B__1928a		BAN 4, 235, 1928
B__1928a		(6th list of new southern double stars; precise measures in later references)
B__1928b	Ma j	van den Bos, W.H.	1928AnLei..144...1V
B__1928b		Ann. Leiden Obs. 14, Pt.4, 1928
B__1928c	Ma -	van den Bos, W.H.	1928MNRAS..88..488F
B__1928c		MNRAS 88, 488, 1928
B__1928d	Ma j	van den Bos, W.H.	1928CiUO...78...13V
B__1928d		Union Obs. Johannesburg Circ. 78, 13, 1928
B__1928e	orb -	van den Bos, W.H.	.
B__1928e		Mem. Copenhagen Acad. 12, 2, 1928
B__1929a	Ma j	van den Bos, W.H.	1929CiUO...80...59V
B__1929a		Union Obs. Johannesburg Circ. 80, 59, 1929
B__1929b	orb -	van den Bos, W.H.	1929CiUO...79...49V
B__1929b		Union Obs. Johannesburg Circ. 79, 49, 1929
B__1929c	Ma -	van den Bos, W.H.	1929BAN.....5..125V
B__1929c		BAN 5, 125, 1929
B__1930a	Ma j	van den Bos, W.H.	1930CiUO...83..135V
B__1930a		Union Obs. Johannesburg Circ. 83, 135, 1930
B__1930b	Ma -	van den Bos, W.H.	1930BAN.....5..179V
B__1930b		BAN 5, 179, 1930
B__1930c	Ma -	van den Bos, W.H.	1930BAN.....5..183V
B__1930c		BAN 5, 183, 1930
B__1931a	Ma -	van den Bos, W.H.	1931MNRAS..92...19F
B__1931a		MNRAS 92, 19, 1931
B__1931b	Ma -	van den Bos, W.H.	1931CiUO...85..183V
B__1931b		Union Obs. Johannesburg Circ. 85, 183, 1931
B__1932a	Ma j	van den Bos, W.H.	1932CiUO...87..273V
B__1932a		Union Obs. Johannesburg Circ. 87, 273, 1932
B__1932b	Ma j	van den Bos, W.H.	1932CiUO...88..324V
B__1932b		Union Obs. Johannesburg Circ. 88, 324, 1932
B__1932C	Ma -	van den Bos, W.H.	1932QB821.A43......
B__1932C		cited in ADS (Aitken Double Star Cat.), 1932
B__1933a	Ma -	van den Bos, W.H.	1933BAN.....7....1V
B__1933a		BAN 7, 1, 1933
B__1933b	J -	van den Bos, W.H.	1933CiUO...90..379V
B__1933b		Union Obs. Johannesburg Circ. 90, 379, 1933
B__1933c	orb -	van den Bos, W.H.	1933CiUO...90..388V
B__1933c		Union Obs. Johannesburg Circ. 90, 388, 1933
B__1933d	Ma j	van den Bos, W.H.	1933CiUO...90..401V
B__1933d		Union Obs. Johannesburg Circ. 90, 401, 1933
B__1934a	Ma -	van den Bos, W.H.	1934CiUO...92...61V
B__1934a		Union Obs. Johannesburg Circ. 92, 61, 1934
B__1934b	orb -	van den Bos, W.H.	1934CiUO...92..102V
B__1934b		Union Obs. Johannesburg Circ. 92, 102, 1934
B__1935a	Ma j	van den Bos, W.H.	1935CiUO...94..134V
B__1935a	+J	Union Obs. Johannesburg Circ. 93, 134, 1935
B__1935b	orb -	van den Bos, W.H.	1935CiUO...94..148V
B__1935b		Union Obs. Johannesburg Circ. 94, 148, 1935
B__1935c	Ma j	van den Bos, W.H.	1935CiUO...94..149V
B__1935c		Union Obs. Johannesburg Circ. 94, 149, 1935
B__1935D	orb -	van den Bos, W.H.	1935QB821.A3.......
B__1935D		letter cited by Aitken, The Binary Stars, 1935
B__1936a	orb -	van den Bos, W.H.	1936CiUO...96..231V
B__1936a		Union Obs. Johannesburg Circ. 96, 231, 1936
B__1936b	Ma j	van den Bos, W.H.	1936CiUO...96..234V
B__1936b		Union Obs. Johannesburg Circ. 96, 234, 1936
B__1937a	orb -	van den Bos, W.H.	1937CiUO...98..341V
B__1937a		Union Obs. Johannesburg Circ. 98, 341, 1937
B__1937b	Ma -	van den Bos, W.H.	1937CiUO...98..362V
B__1937b		Union Obs. Johannesburg Circ. 98, 362, 1937
B__1938a	orb -	van den Bos, W.H.	1938CiUO...99..445V
B__1938a		Union Obs. Johannesburg Circ. 99, 445, 1938
B__1938d	orb -	van den Bos, W.H.	1938CiUO..100..480V
B__1938d		Union Obs. Johannesburg Circ. 100, 480, 1938
B__1938e	Ma j	van den Bos, W.H.	1938CiUO..100..481V
B__1938e		Union Obs. Johannesburg Circ. 100, 481, 1938
B__1940	orb -	van den Bos, W.H.	1940CiUO..102...49V
B__1940		Union Obs. Johannesburg Circ. 102, 49, 1940
B__1943A	Ma -	van den Bos, W.H.	1943AJ.....50..139A
B__1943A		cited by Alden (1943 AJ 50, 139)
B__1941	orb -	van den Bos, W.H.	1941CiUO..104...73V
B__1941		Union Obs. Johannesburg Circ. 104, 73, 1941
B__1945	orb -	van den Bos, W.H.	1945AJ.....51..198V
B__1945		AJ 51, 198, 1945
B__1947	Ma -	van den Bos, W.H.	1947CiUO..105..134V
B__1947		Union Obs. Johannesburg Circ. 105, 134, 1947
B__1947b	Po j	van den Bos, W.H. (in Voute et al.)	1947AnBos...6....3V
B__1947b		Ann. Bosscha Obs. Lembang 6, Pt.3, C1, 1947
B__1948	Ma -	van den Bos, W.H.	1948CiUO..107..259V
B__1948		Union Obs. Johannesburg Circ. 107, 259, 1948
B__1949a	orb -	van den Bos, W.H.	1949CiUO..108..310V
B__1949a		Union Obs. Johannesburg Circ. 108, 310, 1949
B__1949b	orb -	van den Bos, W.H.	1949CiUO..108..311V
B__1949b		Union Obs. Johannesburg Circ. 108, 311, 1949
B__1949c	Ma j	van den Bos, W.H.	1949CiUO..108..312V
B__1949c		Union Obs. Johannesburg Circ. 108, 312, 1949
B__1950a	orb -	van den Bos, W.H.	1950CiUO..109..366V
B__1950a		Union Obs. Johannesburg Circ. 109, 366, 1950
B__1950b	orb -	van den Bos, W.H.	1950CiUO..109..370V
B__1950b		Union Obs. Johannesburg Circ. 109, 370, 1950
B__1950c	Ma -	van den Bos, W.H.	1950CiUO..109..371V
B__1950c		Union Obs. Johannesburg Circ. 109, 371, 1950
B__1951a	Ma j	van den Bos, W.H.	1951CiUO..111...13V
B__1951a	+J	Union Obs. Johannesburg Circ. 111, 13, 1951
B__1951b	orb -	van den Bos, W.H.	1951CiUO..111...11V
B__1951b		Union Obs. Johannesburg Circ. 111, 11, 1951
B__1951c	orb -	van den Bos, W.H.	1951CiUO..112..143V
B__1951c		Union Obs. Johannesburg Circ. 112, 143, 1951
B__1951d	-	van den Bos, W.H.	1951JO.....34...85V
B__1951d		J. Obs. 34, 85, 1951
B__1953a	Ma -	van den Bos, W.H.	1953CiUO..113..185V
B__1953a		Union Obs. Johannesburg Circ. 113, 185, 1953
B__1953b	orb -	van den Bos, W.H.	1953CiUO..113..209V
B__1953b		Union Obs. Johannesburg Circ. 113, 209-219, 1953	1953MNSSA..12...19V
B__1953b		(also MNASSA 12, 19, 1953; MNASSA 12, 57, 1953)	1953MNSSA..12...57V
B__1954	orb -	van den Bos, W.H.	1954CiUO..114..235V
B__1954		Union Obs. Johannesburg Circ. 114, 235, 1954
B__1956a	Ma -	van den Bos, W.H.	1956CiUO..115..266V
B__1956a	+J	Union Obs. Johannesburg Circ. 115, 266, 1956
B__1956b	orb -	van den Bos, W.H.	1956CiUO..115..279V
B__1956b		Union Obs. Johannesburg Circ. 115, 279-284, 1956
B__1956c	orb -	van den Bos, W.H.	1956MNSSA..15...39V
B__1956c		MNASSA 15, 39, 1956
B__1957a	orb -	van den Bos, W.H.	1957CiUO..116..289V
B__1957a		Union Obs. Johannesburg Circ. 116, 289-291, 1957
B__1957b	Ma -	van den Bos, W.H.	1957CiUO..116..291V
B__1957b		Union Obs. Johannesburg Circ. 116, 291, 1957
B__1958	Ma -	van den Bos, W.H.	1958AJ.....63...63V
B__1958		AJ 63, 63, 1958
B__1959a	Mb j	van den Bos, W.H.	1959ApJS....4...45V
B__1959a		ApJS 4, 45, 1959
B__1959b	orb -	van den Bos, W.H.	1959JO.....42...79V
B__1959b		J. Obs. 42, 79, 1959
B__1959c	orb -	van den Bos, W.H.	1959JO.....42...93V
B__1959c		J. Obs. 42, 93, 1959
B__1959d	Ma -	van den Bos, W.H.	1959CiUO..118..308V
B__1959d		Union Obs. Johannesburg Circ. 118, 308, 1959
B__1959e	orb -	van den Bos, W.H.	1959CiUO..118..311V
B__1959e		Union Obs. Johannesburg Circ. 118, 311-312, 1959
B__1960a	Ma -	van den Bos, W.H.	1960CiUO..119..321V
B__1960a		Union Obs. Johannesburg Circ. 119, 321, 1960
B__1960b	Ma j	van den Bos, W.H.	1960PYerO...9....1B
B__1960b	+Mb	Pub. Yerkes Obs. 9, pt. 1, 1960
B__1960c	orb -	van den Bos, W.H.	1960JO.....43..145V
B__1960c		J. Obs. 43, 145, 1960
B__1960d	orb -	van den Bos, W.H.	1960JO.....43..152V
B__1960d		J. Obs. 43, 152, 1960
B__1960e	orb -	van den Bos, W.H.	1960CiUO..119..359V
B__1960e		Union Obs. Johannesburg Circ. 119, 339-340, 1960
B__1960f	orb -	van den Bos, W.H.	1960CiUO..119..341V
B__1960f		Union Obs. Johannesburg Circ. 119, 341-343, 1960
B__1961a	Ma -	van den Bos, W.H.	1961CiUO..120..353V
B__1961a		Union Obs. Johannesburg Circ. 120, 353, 1961
B__1961b	orb -	van den Bos, W.H.	1961CiUO..120..374V
B__1961b		Union Obs. Johannesburg Circ. 120, 374-375, 1961
B__1961c	orb -	van den Bos, W.H.	1961CiUO..120..377V
B__1961c		Union Obs. Johannesburg Circ. 120, 377-379, 1961
B__1961d	orb -	van den Bos, W.H.	1961CiUO..120..380V
B__1961d		Union Obs. Johannesburg Circ. 120, 380-381, 1961
B__1961e	orb -	van den Bos, W.H.	1961PASP...74..201V
B__1961e		PASP 74, 201, 1961
B__1962a	Ma -	van den Bos, W.H.	1962AJ.....67..141V
B__1962a		AJ 67, 141, 1962
B__1962b	orb -	van den Bos, W.H.	1962AJ.....67..552V
B__1962b		AJ 67, 552, 1962
B__1962c	orb -	van den Bos, W.H.	1962JO.....45...55V
B__1962c		J. Obs. 45, 55, 1962
B__1962d	Ma j	van den Bos, W.H.	1962AJ.....67..555V
B__1962d		AJ 67, 555, 1962
B__1963a	Ma -	van den Bos, W.H.	1963AJ.....68...57V
B__1963a		AJ 68, 57, 1963
B__1963b	Ma j	van den Bos, W.H.	1963AJ.....68..582V
B__1963b		AJ 68, 582, 1963
B__1964a	orb -	van den Bos, W.H.	1964ROCi..123...62V
B__1964a		Republic Obs. Circ. 123, 62, 1964
B__1964b	orb -	van den Bos, W.H.	1964JO.....47...34V
B__1964b		J. Obs. 47, 34, 1964
B__1965a	Ma -	van den Bos, W.H.	1965ROCi..124...70V
B__1965a		Republic Obs. Circ. 124, 70, 1965
B__1965b	orb -	van den Bos, W.H.	1965ROCi..124...86V
B__1965b		Republic Obs. Circ. 124, 86, 1965
B__1966a	Ma -	van den Bos, W.H.	1966ROCi..125...93V
B__1966a		Republic Obs. Circ. 125, 93, 1966
B__1966b	orb -	van den Bos, W.H.	1966ROCi..125..112V
B__1966b		Republic Obs. Circ. 125, 112, 1966
B__1966c	orb -	van den Bos, W.H.	1966ROCi..125..118V
B__1966c		Republic Obs. Circ. 125, 118, 1966
B__1966d	orb -	van den Bos, W.H.	1966ROCi..125..119V
B__1966d		Republic Obs. Circ. 125, 119-120, 1966
B__1967	Ma -	van den Bos, W.H.	1967ROCi..126..127V
B__1967		Republic Obs. Circ. 126, 127, 1967
B__1967b	orb -	van den Bos, W.H.	1967JO.....13..119V
B__1967b		J. Obs. 13, 119, 1967
B__1968	Ma -	van den Bos, W.H.	1968ROCi..127..157V
B__1968		Republic Obs. Circ. 127, 157, 1968
B__9999	Ma -	van den Bos, W.H.	...................
B__9999		Unpublished, manuscript or reference not found.

WDS HISTORIC DATA

coord_2000	discov_num	comp	epoch	obs	pa	sep	mag_pri	mag_sec	spectr	notes	coord_arcsec_2000
17252-4512	B 1856		1991	3	140	1.6	10.57	10.94	A3/5IV/V		172509.52-451143.1

If you need more information about this double, apply for a data request form to the WDS.

WDS 17252-4512 B 1856 (HD 157388) : VISUAL OBSERVATIONS REPORTS

No records found.

WDS 17252-4512 B 1856 (HD 157388) : MEASURES

No records found.

WDS 17252-4512 (HD 157388) : VIRTUAL EYEPIECE

Click on the map to see the double of your interest.
Pass over with the mouse cursor to display the catalog designation.

WDS 17252-4512 (HD 157388) : ALADIN DSS IMAGE @ 17^h 25^m 09.52^s -45° 11' 43.1"

DSS color DSS blue 2MASS AllWISE GALEX SDSS9 XMM PanSTARRS

WDS 17252-4512 B 1856 (HD 157388) : NEIGHBORHOODS

Click on the map to see the double of your interest.
Pass over with the mouse cursor to display the catalog designation.

Show	name	coord_2000	discov#	comp	pa	sep	dist(')
Show		17252-4512	B 1856		140	1.6
Show		17257-4516	B 1857		51	4.5	8
Show		17237-4510	I 593		282	0.8	16
Show		17253-4451	SKF1055		47	7.6	21
Show		17246-4445	DON 836		87	1.3	28
Show		17228-4537	EVS 30	AB	268	14.4	36
Show		17228-4537	EVS 30	AC	215	18.0	36
Show		17228-4537	GAA 15	Aa,Ab	235	0.0	36
Show		17217-4524	DON 831		30	0.3	38
Show		17213-4523	CPO 520		70	5.3	42
Show		17267-4551	ARY 109		155	10.5	43
Show		17213-4526	BRT 958		210	2.8	43
Show		17269-4551	HJ 4949	AB	251	2.1	43
Show		17269-4551	DUN 216	AC	312	102.5	43
Show		17280-4545	B 1858		237	2.2	45
Show		17294-4520	CPO 528		357	4.7	46
Show		17241-4425	DON 834		20	1.6	49
Show		17283-4550	DON 840		12	1.3	51
Show		17207-4443	CPO 519		223	5.7	56
Show		17254-4611	RST 927		312	2.4	60
Show		17274-4416	DON 839		274	2.4	61
Show		17206-4549	BRT 957		313	3.1	61
Show		17227-4611	BRT 961		327	4.6	65
Show		17270-4408	TDT 357		282	0.6	67
Show		17195-4443	TDT 305		320	0.5	67
Show		17313-4501	DON 841		29	2.2	67
Show		17267-4407	I 1083		318	0.8	67
Show		17260-4403	DON 837		328	3.8	70
Show		17193-4441	CPO 518		253	3.3	70
Show		17187-4446	BRT 955	AB	290	3.1	74
Show		17187-4446	BRT 955	AC	149	5.6	74
Show		17312-4552	BRT 975		134	5.1	76
Show		17200-4610	HJ 4936		76	7.4	80
Show		17259-4352	TDT 346		94	0.4	81
Show		17303-4412	I 1005	AB	94	2.6	81
Show		17303-4412	I 1005	AC	101	32.8	81
Show		17290-4358	DUN 217		168	13.4	85
Show		17242-4348	HU 1523		266	7.4	85
Show		17194-4413	HDO 269		233	0.1	85
Show		17320-4559	ARY 93		206	56.4	87
Show		17318-4602	I 40		210	20.5	87
Show		17332-4531	I 603		78	1.3	88
Show		17184-4603	DON 830		98	2.3	88
Show		17170-4531	BRT 954		53	3.5	88
Show		17216-4632	RST 920		230	0.3	89
Show		17321-4420	COO 214	AB	38	8.8	91
Show		17321-4420	COO 214	BC	342	10.2	91
Show		17181-4605	HJ 4929		226	10.6	92
Show		17204-4352	TDT 313		96	1.3	95
Show		17298-4638	SHN 220		-1	0.2	99
Show		17347-4508	RSS 451		154	11.2	101

WDS 17252-4512 : COMPONENTS

	A
B	pa=149.6° sep=1.41"

17252-4512 A

Componente originario normalizzato	AB	Name	HD 157388	Coord arcsec 2000	172509.52-451143.1	Mag	10.57
Spectral class	A3/5IV/V (white)	PmRA	3.00	PmDE	-2.0	SAO	227930
Tycho2	8341-00186-1	HD	157388	DM	CP-45 8549

Tycho2

Tycho2	8341-00186-1	Pflag	P	RAmdeg	261.28966356	DEmdeg	-45.19530422
PmRA	2.6	PmDE	-1.7	E RAmdeg	25	E DEmdeg	33
E pmRA	2.4	E pmDE	2.2	EpRAm	1990.58	EpDEm	1989.18
Num	3	Q RAmdeg	1.0	Q DEmdeg	0.1	Q pmRA	1.0
Q pmDE	0.1	BTmag	10.606	E BTmag	0.042	VTmag	10.574
E VTmag	0.054	Prox	16	TYC	T	HIP
CCDM		RAdeg	261.28955194	DEdeg	-45.19521389	EpRA 1990	1.77
EpDE 1990	1.84	E RAdeg	24.8	E DEdeg	33.7	Posflg	D
Corr	-0.1

SAO

SAO	227930	DelFlag		RA1950		PmRA1950	0.0009
DE1950		PmDE1950	-0.013	Vmag	9.9	SpType	A2
Double code		Source	48	CatNum	16144	DM	CP-45 8549
DMcomp		BDsup		HD	157388	M HD	0
GC		RA1950rad	4.54435365	DE1950rad	-0.78803317	PmRA2000	0.0009
PmDE2000	-0.013

CCDM

Ccdm	17252-4512	RComp		Comp	A	Note1
Note2		Discov num		DRAs	-2.46	DDEs	16.2
R dRAs	10	Year		Theta		Rho
Obs	2	Vmag	10.2	Sp	A2	PmNote	*
PmRA	10	PmDE	-13	Dm number	-4511498	Cat1	CD
Name2	227930	Cat2	SAO	HD	157388	M HD
ADS BDS		M ADS BDS		N IDS		IDS	17178S4506A
HIC

17252-4512 B

Componente originario normalizzato	AB		Coord arcsec 2000	172509.59-451144.3		Mag	10.94		PmRA	3.00
PmDE	-2.0		Tycho2	8341-00186-2		Calc delta mag	0.37		Calc coord	yes

Tycho2

Tycho2	8341-00186-2	Pflag	P	RAmdeg	261.28966356	DEmdeg	-45.19530422
PmRA	2.6	PmDE	-1.7	E RAmdeg	25	E DEmdeg	33
E pmRA	2.4	E pmDE	2.2	EpRAm	1990.58	EpDEm	1989.18
Num	3	Q RAmdeg	1.0	Q DEmdeg	0.1	Q pmRA	1.0
Q pmDE	0.1	BTmag	11.340	E BTmag	0.075	VTmag	10.943
E VTmag	0.081	Prox	16	TYC		HIP
CCDM		RAdeg	261.28995333	DEdeg	-45.19555167	EpRA 1990	1.76
EpDE 1990	1.83	E RAdeg	41.6	E DEdeg	56.8	Posflg	D
Corr	-0.1

CCDM

Ccdm	17252-4512	RComp		Comp	B	Note1
Note2		Discov num	B 1856	DRAs		DDEs
R dRAs		Year	1930	Theta	143	Rho	1.6
Obs	2	Vmag	11.0	Sp		PmNote
PmRA		PmDE		Dm number		Cat1
Name2		Cat2		HD		M HD
ADS BDS		M ADS BDS		N IDS		IDS	17178S4506B
HIC