Strong iron line from NGC3516

Kyoko Nogami$^1$, Tatehiro Mihara$^1$, Hitoshi Negoro$^1$, 
and Hagai Netzer$^2$

$^1$RIKEN, Wako, Saitama, Japan \newline
$^2$Tel Aviv Univ., Tel Aviv, Israel \newline


$ASCA$ observations of Seyfert 1 galaxy NGC3516 
are reported. 
The X-ray flux decreased monotonously,
as the SIS0 count rates were 
 2.50, 1.52 and 0.98 c/s 
on 1994 April, 1995 March and 1998 April, respectively.
In the most recent observation, from 1999 November 30 for about 3 days,
SIS0 count rate was 0.19 c/s.
The remarkable points in this observation are 
that iron line is very strong (equivalent width $\sim$345 eV),
and that Power-Law photon index
 is very flat, $\Gamma_{3-10keV}$=0.85.
These results are similar to observation with Ginga in 1989.

We can solve the problem of the flat spectrum 
by introducing two absorbers.
While the continuum flux varied by a factor of 1.5,
the flux of iron line was marginally constant.
Possibly iron line is constant at least for five years.
We can interpret that iron line looked very strong 
because the continuum flux decreased in 1999.
If the flux of iron line is variable, 
we can interpret that iron line is emitted 
mainly from the matter in Broad Line Region or outside.