[vsnet-alert 9082] New SU UMa-type dwarf nova in the field of NGC 6688

[Taichi Kato]

   From baavss-alert.  Wolfgang Renz has relayed the info of the
following suspected new object near NGC 6688.  The object now
turns out to be a new SU UMa-type dwarf nova.  Given the (apparent)
large outburst amplitude and short superhump period, the object
would be a good candidate for a WZ Sge-type dwarf nova.
Further observations are encouraged.

===

Did you make 1 image and the 2nd is a deconvoluted one of the first ?
Or did you actually make two images ?

Was it taken:
    2006-09-20 UT 19:30
or
    2006-10-20 UT 19:30
?

The MPC doesn't show an MP down to 30 mag at that position for both
dates.

The lower object of the suspect "double" is for sure a star that is also
present in the DSS images:
    RA =3D 18:40:28.9 DEC =3D +36:17:41

There might be a number of reasons (like a cosmic, dust on the chip,
a reflection of the brighter star in the lower left of the image, or bad
calibration frames) why there might be an "object" above the star.

It would be very helpful, if you would give the position of the object and
more data on your setup and especially on the images for your "alerts"
(in your emails and also on your web page). Having to guess what the
images represent, how they were processed (deconvolution, histogram
streching, ...) and where they come from are too many unknown variables
that will influence every judgement.

Not being able to save the images on your homepage directly for further
inspection (due to using MS Word for creating it) doesn't help either.
Having to open the html source, copying the relative path and adding it to
the URL might not be known by everybody.

Clear skies
  Wolfgang

--=20
Wolfgang Renz, Karlsruhe, Germany
Rz.BAV =3D WRe.vsnet =3D RWG.AAVSO

===

4 hrs of V and I-band CCD photometry of this new object, reported earlier by 
astronomers at Crni Vrh Observatory of the University of Ljubljana, shows a 
strong superhump signal with peak-to-peak amplitude 0.2 mag around a mean V mag 
of 15.10 indicating it is probably a UGSU-type CV. The V-I colour index is very 
close to zero.

The mean superhump period over this 4 hr interval is 0.0541 +/- 0.0027d, using 
Peranso.

These measurements used USNO-B1 1028-0043851 as a comparison, thanks to Wolfgang 
Renz for circulating this information. Equipment was 0.35m SCT with SXV-H9 CCD.

Position measured as RA 03 29 12.26 +/- 0.19  Dec +12 50 17.54 +/- 0.12 (2000) 
using Astrometrica and UCAC2.

Further time-series observations are encouraged.

Regards,
David Boyd (BDG),
West Challow, UK