[vsnet-alert 9988] Re: Discovery of another optically violently variable quasar 4C 09.57

[Seiichi Yoshida]

Dear colleagues,

I investigated the ASAS-3 V-band survey. The quasar was not recorded at
all from 2003 Feb. 27 to 2007 Mar. 30. So it must have been fainter than
15 mag all through the period for four years.

But the ASAS-3 data shows the quasar suddenly brightened up to 13.9 mag
on 2007 Apr. 2, then it faded down to 15 mag until 2007 August.

* ASAS-3 (V) magnitude

2007 Apr.  2.37159  13.885
          12.37676  14.451
          15.35598  14.085
          23.36967  13.982
     May  10.31560  14.765
     July 11.16361  14.611
     Aug. 18.05158  14.997
          20.06035  15.008

Here is the ASAS-3 light curve:

  http://www.astrouw.edu.pl/cgi-asas/asas_variable/175133+0939.0,asas3,0,0,500,320

Best regards,

> Dear colleagues,
> 
> We discovered a quasar 4C 09.57 is an optically violently variable
> quasar in the course of the MISAO Project.
> 
>   http://www.aerith.net/misao/variable/MisV1439.html
> 
> This is our second optically violently variable quasar discovery,
> after QSO B0133+47 discovered on 2008 Feb. 8. However, we do not know
> whether the variation of this quasar was already known or not.
> 
> The variation of this quasar was discovered by Seiichi Yoshida (MISAO
> Project) in the MISAO Project variable star survey. It was picked up
> as one of the new variable star candidates from Youichirou Nakashima
> (Okayama, Japan)'s unfiltered CCD images on 2007 July 30 and 2008
> Mar. 20 by the PIXY System 2. It was bright as 14.4 mag on 2007 July
> 30, but not visible on 2008 Mar. 30 (fainter than 15.3 mag).
> 
> Yoshida checked Nakashima's CCD images on 2007 May 31 and found it was
> bright as 14.1 mag.
> 
> Ken-ichi Kadota observed it on 2008 Mar. 22, and confirmed that now it
> is so faint as 18.1 mag.
> 
> Therefore, we discovered the variation of this quasar is at least 4
> mag.
> 
> Here are the data of this quasar:
> 
>   USNO-A2.0 0975.09850990  17h51m32s.817 +09o39'00".61  Mag(R):17.0  Mag(B):17.9
>   4C 09.57  BLL  17 51 32.8186 +09 39 00.728  17.83B
>   OT 081  17h51m32s.8 +09o39'02"  16.78 mag(V)  B-V:0.68  U-B:-0.47  -24.1 mag(abs)  z=0.320
>   1AXG J175132+0939  17h51m32s.66 +09o39'03".9  Value(ct/ks):77.6  Hard:-0.08
>   LEDA 84878  17h51m32s.8 +09o39'00"
> 
> We the MISAO Project registered it as the 1439th new variable star,
> and assigned the designation "MisV1439".
> 
>   MisV1439
>     R.A.  17h51m32s.83
>     Decl. +09o39'01".0  (2000.0)
>     Mag.  14.1-18.1C
>     Type  OVV-QSO
> 
>   http://www.aerith.net/misao/data/misv.cgi?1439
> 
> Here are the observation data by the MISAO Project:
> 
>   2007 May  31.60  14.1 mag  (*1)
>        July 30.55  14.4 mag  (*1)
>   2008 Mar. 20.85 <15.3 mag  (*1)
>        Mar. 22.78  18.1 mag  (*2)
> 
>   (*1) Youichirou Nakashima  0.25-m f/4.2 Wright-Schmidt reflector + SBIG ST-1001E
>   (*2) Ken-ichi Kadota  0.25-m f/5.0 reflector + SBIG ST-9E
> 
> I also investigated the past brightness of this quasar in the
> Digitized Sky Survey POSS-I / POSS-II plates using:
> 
>   USNO Flagstaff Station Integrated Image and Catalogue Archive Service
>   http://www.nofs.navy.mil/data/FchPix/cfra.html
> 
> It was faint around 17 mag in 1956. It had been almost constant around
> 15-16 mag from 1990 to 1994. But it brightened up to about 13.5 mag in
> 1995.
> 
> So now the quasar seems to be faintest in the history.
> 
> The SIMBAD shows that this quasar was reported in the
> (Fiorucci+Tosti+Rizzi, 1998) paper. It was recorded as 11.95 mag(V) as
> [FTR98] 1749+096 C1, but other records show it around 14.5 mag(V). So
> maybe an outburst was recorded in their observations.
> 
> About the MISAO Project and the PIXY system 2:
>   http://www.aerith.net/misao/
> 
> Best regards,
> 
> --
> Seiichi Yoshida
> comet at aerith.net
> http://www.aerith.net/

--
Seiichi Yoshida
comet at aerith.net
http://www.aerith.net/