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Name
  HZ Her  
AAVSO UID
000-BBY-240 (16191 observations)  
Constellation
Hercules Sequence
J2000.0
16 57 49.75 +35 20 32.7  (254.45729 +35.34242) Search nearby
B1950.0 16 56 01.69 +35 25 05.2
Proper motion
RA: -0.2 +/- 3.1 mas/yDec: -3.3 +/- 7.5 mas/ySource: UCAC4
Galactic coord. 58.149 +37.523
Other names

(Internal only)
Please note that aliases shown in grey link to obsolete records.
1RXS J165749.6+352022 1SWASP J165749.80+352032.8 2RXP J165749.4+352033
AAVSO 1654+35 AN 142.1936 ASASSN-V J165749.81+352032.5
Her X-1 IOMC 2598000079 ROTSE1 J165749.74+352032.4
X 16560+354    
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Variability type
LMXB:/XPR+E
Spectral type A7IVe
Mag. range
12.8 - 15.2 B
Discoverer --
Epoch
--
Outburst --
Period 34.875 d
Rise/eclipse dur. --
Remarks
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1 Otero, Sebastian Alberto The main photometric period of 34.875 d. is caused by the precession of the neutron star accretion disk and the reflection effect. Orbital elements: 2441397.584 + 1.700175 x E. X-ray eclipses.
2 GCVS Team Her X-1 = 4U 1656 + 35. Lx/Lopt = 2 - 60. The Table gives elements for light minima due to eclipsing variability and the reflection effect. Min I coincides with the X-ray eclipse. Shallow Min II may be present. The reflection effect causes variations with Delta(m) up to 1.5m. A cycle of 34.875d duration is observed in X-ray band; the source is faint during two thirds of the cycle. The optical light curve changes are observed during the 35d cycle [N.E.Kurochkin, Perem. Zvezdy 18, N5, 425, 1972.]. According to [W.Wenzel, H.Gessner, MVS 6, H.3, 61, 1972.], during JD2427543 - 657 and JD2428630 - 29789 the strong reflection effect was absent; the star was still varying with P = 1.7d and had Delta(m) ~0.5m, Min I = Min II. In [C.A.Jones, Wm.Forman, Wm.Liller, BAAS 5, N1, part 1, 32, 1973.] it is stated that such intervals with no reflection effect, of 8d to 7a duration, took place for almost half the time since 1890. The light changes during such intervals are in the range 14.7m - 15.2m pg. Since 1957 intervals without the reflection effect were not observed. In June - July 1983 the predicted phases of high X-ray flux did not take place, but the reflection effect did not disappear [IAU Circ N3841, 1983.]. Secondary light variations: P1 = 1.0977d (delta(B1) = 0.33m), P2 = 0.871173d*E (delta(B2) = 0.10m), P3 = 1.623846d*E (delta(B3) = 0.17m) [N.E.Kurochkin, Pis'ma Astron. Zh. 1, N7, 27, 1975.]. X-ray pulsar, P = 1.2377991s (JD2443357), dP/dt/P = (-2.9 +- 0.2)*10**(-6)/yr [P.C.Joss, F.Li, J.Nelson, J.Middleditch, ApJ 235, 592, 1980.], sometimes noticeable also in the optical range [D.O.Lamb, J.M.Sorvari, IAU Circ N2422, 1972.]. Rapid brightness flickering.
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References
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1 Bob Nelson's O-C files, 2016 --
2 J. Alfonso-Garzon, A. Domingo, J.M. Mas-Hesse, A. Gimenez, 2012,
arXiv:1210.0821 [astro-ph.IM] (online info)		 2012arXiv1210.0821A
3 Multicolor photoelectric WBVR observations of the close binary system HZ
Her = Her X-1 in 1986-1988. Method and observations		 2011ARep...55..230S
4 Norton A.J. et al., 2007, astro-ph/0702631 2007astro.ph..2631N
5 C.Akerlof et al., AJ 119, 1901, 2000. 2000AJ....119.1901A
6 R.Hudec, W.Wenzel, BAC 27, N6, 325, 1976. 1976BAICz..27..325H
7 N.E.Kurochkin, Perem. Zvezdy 18, N5, 425, 1972. 1972PZ.....18..425K
External Links
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Location    Go   
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Catalog Data
Information from selected catalogs obtained by cross-matching to 2 arc seconds using the CDS X-Match Service. These data may not be complete.
2MASS J = 13.73H = 13.61K = 13.63J - K = 0.10
AllWISE W1 = 13.22W2 = 13.15W1 - W2 = 0.07
APASS-DR9 B = 13.52V = 13.50g' = 13.43r' = 13.63i' = 13.73B - V = 0.02
GALEX-DR5 FUV = 19.37NUV = 14.48FUV - NUV = 4.89
SDSS-DR12 u = 13.97g = 13.69r = 13.69i = 13.92z = 14.02u - g = 0.28r - i = -0.23
Images
Please review Digitized Sky Survey Acknowledgment and Copyright.
Size 5' x 5' (297 x 298 pixels)
Center 16 57 49.75 +35 20 32.7 (J2000)
Source STScI
Survey

Red, all sky, 1.0 arcsec/pixel
  Negative
Supporting Documents
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Revision History
Currently approved revision is checked. Click revision number to view details of that revision.
3 Otero, Sebastian Alberto 2011-05-24 00:23 UTC Primary record creation. Variability and spectral type from reference.
2 Admin, VSX 2010-01-05 04:43 UTC Position updated from the GCVS version of November 2009.
1 Admin, VSX 2005-12-18 01:33 UTC Initial upload.

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