[vsnet-alert 4473] Re: (fwd) SN suspect in NGC 5128

["Berto Monard" <LAGMonar@csir.co.za>]

Dear Taichi,

Cen A is one of my regular targets for SN search and lies conveniently placed on my way to observing V803 Cen.
My last observation of Cen A took place on 24.79/03/2000. Nothing extra was seen on that and any previous occasions up to a visual detection level of magnitude 14.
Two brightish foreground stars to the galaxy have confused observers in the past. I still believe the dreadful NGC5128 V17 is identical to one of those two foreground stars, but then I could be wrong!

Due to the galaxy brightness and the standard overexposure of Cen A images those two foreground stars are never properly depicted in published images including those of the DSS.
The most Southerly of the two stars is around magnitude 11 and lies actually a bit outside the main image of Cen A ( I think this is V17..) , the other star lies closer to the centre and is of approximate magnitude 12.5. Could this be the star reported as a possible SN?
For a more complete description of the galaxy as seen through a 12.5", there are another two foreground stars, each of them relatively close to one of the two brighter foreground stars. They are both around magnitude 14.5 and I need good sky transparency to see them from my location...

Unless I have had a blind eye during recent observations of Cen A I would state that there is no extra star (SN) visible in Cen A.

Best regards,

Berto Monard
Pretoria


>>> Taichi Kato <tkato@kusastro.kyoto-u.ac.jp> 03/27/00 08:26AM >>>

   We have received the following report.  Could someone check?
  (Any relation with the previously reported suspected object, =NGC5128 V17?)

From: "Cris Ellis" <mrktg@acromet.com.au>
Date: Mon, 27 Mar 2000 13:38:34 +1000
Subject: Suspect SN

On Friday 10 March 2000, at 9.38pm Eastern Australian Summertime I =
observed a potential SN from our Societies dark sky viewing site located =
to the East of Melbourne, Australia.

The object observed was a singularly outstanding star that I have not =
seen before and is massively brighter than any other star in the host =
galaxy. The suspect SN lies within NGC5128, the Centaurus A galaxy, =
which lies 14 Million light years distant. The star was massively =
brighter than any individual star in the galaxy, and was found in the =
north east corner of the galaxy through the telescope eyepiece (upside =
down through the eyepiece of course).

Notes on observation: The suspect object appeared clearly to lie within =
the galaxy, with brightening directly conducive to it=92s being a SN. =
The telescope used for observation is an eighteen month old 12.5 inch =
f5.3 1/20 wave Newtonian Dobsonian unit. It is an outstanding telescope =
which I constructed personally by hand. Maximum performance of the =
object was gained with a Takahashi 7.5mm ocular which gave approximately =
250 magnifications.

The star halo of the north and south hemispheres of the elliptical =
galaxy are easily cut by the dust lane of the spiral galaxy that is in =
collision in the stellar object. As Centaurus A is a galactic collision =
of a elliptical & spiral galaxy as I am sure you are aware. The suspect =
SN is located to the lower left portion of the galaxy, well away from =
the collision zone where as David Malin and others photographs indicate =
such extreme stellar birth.

Indeed we checked a photograh by Malin at site in a book at the time of =
viewing in order to check our findings which gave us considerable =
enthusiasm as there lies no bright object at that location on the =
wonderful AAT photograph that Malin took.

I wish to firstly enquire for this to be confirmed as a SN, and secondly =
request whether it has been previously claimed as discovered by other =
astronomers. If my record of this is the first then I would like to =
place personal claim on this object as discoverer.

Thanking you in anticipation of your most valued assistance in this =
matter.

Rgds,

Cris Ellis

President

Astronomical Society of Melbourne Inc

Melbourne,

Australia.

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