Discovery of another optically violently variable quasar 4C 09.57

[Tass Mailing List <tass@mail.alembic.net>]

Date: Sun, 23 Mar 2008 14:33:22 +0900 (JST)
From: Seiichi Yoshida <comet@aerith.net>
To: tass@mail.alembic.net
Subject: Discovery of another optically violently variable quasar 4C 09.57

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@aerith.net
http://www.aerith.net/