J/A+A/486/99 Long-term spectral variability of NGC 4151 (Shapovalova+, 2008) ================================================================================ Long-term variability of the optical spectra of NGC 4151. I. Light curves and flux correlations. Shapovalova A.I., Popovic L.C., Collin S., Burenkov A.N., Chavushyan V.H., Bochkarev N.G., Benitez E., Dultzin-Hacyan D., Kovacevic A., Borisov N., Carrasco L., Leon-Tavares J., Mercado A., Valdes J.R., Vlasuyk V.V., Zhdanova V.E. =2008A&A...486...99S ================================================================================ ADC_Keywords: Active gal. nuclei ; Galaxies, spectra Keywords: galaxies: active - galaxies: individual: NGC 4151 Abstract: Results of a long-term spectral monitoring of the active galactic nucleus of NGC 4151 are presented (11 years, from 1996 to 2006). High quality spectra (S/N>50 in the continuum near H{alpha} and H{beta}) were obtained in the spectral range ~4000 to 7500{AA}, with a resolution between 5 and 15 {AA}, using the 6-m and the 1-m SAO's telescopes (Russia), the GHAO's 2.1-m telescope (Cananea, Mexico), and the OAN-SPM's 2.1-m telescope (San-Pedro, Mexico). The observed fluxes of the H{alpha}, H{beta}, H{gamma} and HeII{lambda}4686 emission lines and of the continuum at the observed wavelength 5117{AA}, were corrected for the position angle, the seeing and the aperture effects. We found that the continuum and line fluxes varied strongly (up to a factor 6) during the monitoring period. The emission was maximum in 1996-1998, and there were two minima, in 2001 and in 2005. As a consequence, the spectral type of the nucleus changed from a Sy1.5 in the maximum activity state to a Sy1.8 in the minimum state. The H{alpha}, H{gamma} and He{lambda}4686 fluxes were well correlated with the H{beta} flux. The line profiles were strongly variable, showing changes of the blue and red asymmetry. The flux ratios of the blue/red wings and of the blue (or red) wing/core of H{alpha} and H{beta} varied differently. We considered three characteristic periods during which the H{beta} and H{alpha} profiles were similar: 1996-1999, 2000-2001 and 2002-2006. The line to continuum flux ratios were different; in particular during the first period (1996-2001), the lines were not correlated with the continuum and saturated at high fluxes. In the second and third period (2002-2006), where the continuum flux was small, the H{alpha} and H{beta} fluxes were well correlated to the continuum flux, meaning that the ionizing continuum was a good extrapolation of the optical continuum. The CCFs are often asymmetrical and the time lags between the lines and the continuum are badly defined indicating the presence of a complex BLR, with dimensions from a 1 to 50 light-days. We discuss the different responses of H{beta} and H{alpha} to the continuum during the monitoring period. Objects: ------------------------------------------------ RA (2000) DE Designation(s) ------------------------------------------------ 12 10 32.6 +39 24 20.6 NGC 4151 = UGC 7166 ------------------------------------------------ File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 60 220 Log of the spectroscopic observations table3.dat 36 8 Corrections for the position angle effect table45.dat 94 12 Correction for seeing effects table7.dat 66 220 Observed continuum, H{alpha}, H{beta}, H{gamma} and HeII{4686} fluxes, reduced to the 6m telescope aperture (2"x6") -------------------------------------------------------------------------------- See also: J/AZh/71/189 : Gas Kinematics from Halpha line in NGC 4151 (Sergeev, 1994) J/A+A/324/904 : NGC 4151 line-continuum diagram sequences (Malkov+ 1997) J/PAZh/25/403 : Optical variability of NGC 4151 (Lyuty+, 1999) J/PAZh/27/83 : Nuclear activity of NGC 4151 in 1989-2000 (Doroshenko+, 2001) Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 10 A10 "DD/MM/YYYY" ObsDate UT-date of the observation 12- 20 F9.1 d JD Julian Date 22- 26 A5 --- Tel Code assigned to each telescope+equipment (1) 28- 30 F3.1 arcsec AperW The projected spectrograph entrance apertures (Slit Width) 32- 36 F5.2 arcsec AperL The projected spectrograph entrance apertures (along Slit) 38- 41 I4 0.1nm lam1 Lower wavelength of the spectral range 42 A1 --- --- [-] 43- 46 I4 0.1nm lam2 Upper wavelength of the spectral range 48- 51 F4.1 0.1nm Res Spectral resolution 53- 55 I3 deg PA ? Slit position angle 57- 60 F4.2 arcsec Seeing ? Mean seeing -------------------------------------------------------------------------------- Note (1): Codes as follows: L(N) = SAO (Russia), Inst.: 6m+Long slit, Focus: Nasmith L(U) = SAO (Russia), Inst.: 6m+UAGS, Focus: Prime L(S) = SAO (Russia), Inst.: 6m+Scorpio, Focus: Prime GH = Gullermo Haro(Mexico), Inst.: 2.1m+B&C, Focus: Cassegrain S-P = San-Pedro(Mexico), Inst.: 2.1m+B&C, Focus: Cassegrain L1(G) = SAO (Russia), Inst.: 1m+GAD, Focus: Cassegrain L1(U) = SAO (Russia), Inst.: 1m+UAGS+CCD2K, Focus: Cassegrain -------------------------------------------------------------------------------- Byte-by-byte Description of file: table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I3 deg PA Slit position angle in degrees 5- 7 F3.1 arcsec AperW The projected spectrograph entrance apertures (Slit Width) 9- 12 F4.1 arcsec AperL The projected spectrograph entrance apertures (along Slit) 14- 18 F5.3 --- kp(H{beta}) Slit position angle corrections for emission lines (H{beta}) (1) 20- 24 F5.3 --- e_kp(H{beta}) ? Estimated PA correction error for emission line 26- 30 F5.3 --- kp(cnt) Position angle (PA) corrections (1) for continuum flux 32- 36 F5.3 --- e_kp(cnt) ? Estimated PA correction error for continuum flux -------------------------------------------------------------------------------- Note (1): correction in the flux depending on the position angle of the slit k = F(90)/F(i) (see section 2.3 of paper) -------------------------------------------------------------------------------- Byte-by-byte Description of file: table45.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 F3.1 arcsec SeeingL ? Lower value of the interval of seeings 4 A1 --- --- [-] 5- 7 F3.1 arcsec SeeingU ? Upper value of the interval of seeings 9- 12 F4.2 arcsec Seeing ? Mean seeing 14- 18 F5.3 --- ksHb ? Our seeing correction for the emission lines flux (H{beta}) 21- 30 A10 --- apksHb Aperture for ksHb 33- 37 F5.3 --- e_ksHb ? Estimated seeing correction error 39- 43 F5.3 --- ksHbP ? Peterson's seeing correction for the emission lines flux (H{beta}) (2) 46- 52 A7 --- apksHbP Aperture for ksHP 54- 59 F6.3 10-16W/m2/nm Gs ? Our host galaxy seeing correction for the continuum flux (1) 62- 71 A10 --- apGs Aperture for Gs 74- 78 F5.3 10-16W/m2/nm e_Gs ? Estimated host galaxy seeing correction error (1) 80- 85 F6.3 10-16W/m2/nm GsP ? Peterson's host galaxy seeing correction for the continuum flux (2) 88- 94 A7 --- apGsP Aperture for GsP -------------------------------------------------------------------------------- Note (1): In units of 10^-14^erg/s/cm^2^/{AA} Note (2): Peterson et al., 1995PASP..107..579P -------------------------------------------------------------------------------- Byte-by-byte Description of file: table7.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 9 F9.1 d JD Julian date 11- 15 F5.2 10-16W/m2/nm F(cont) Continuum flux at 5117{AA} (2)(1) 17- 20 F4.2 10-16W/m2/nm e_F(cont) Estimated continuum flux error (2) 22- 26 F5.2 fW/m2 F(Ha) ? H{alpha} total flux (3) 28- 31 F4.2 fW/m2 e_F(Ha) ? H{alpha} flux error (1)(3) 33- 37 F5.2 fW/m2 F(Hb) ? H{beta} total flux (3) 39- 42 F4.2 fW/m2 e_F(Hb) ? H{beta} flux error (3) 44- 48 F5.3 fW/m2 F(Hg) ? H{gamma} total flux (1)(3) 50- 54 F5.3 fW/m2 e_F(Hg) ? H{gamma} flux error (3) 56- 60 F5.3 fW/m2 F(HeII) ? HeII{lambda}4686{AA} total flux (1)(3) 62- 66 F5.3 fW/m2 e_F(HeII) ? HeII{lambda}4686{AA} flux error (3) -------------------------------------------------------------------------------- Note (1): The fluxes are corrected for position angle (to PA=90{deg}), seeing and aperture effects. Note (2): In units of 10^-14^erg/s/cm^2^/{AA} Note (3): In units of 10^-12^erg/s/cm^2^ -------------------------------------------------------------------------------- Acknowledgements: Alexander Burenkov, ban(at)sao.ru ================================================================================ (End) Alexander Burenkov [SAO RAS], Patricia Vannier [CDS] 08-Jul-2008