(cba:news) SDSS1146+67 and AM CVn

[Joe Patterson]

Dear CBAers,

See Enrique's note below about this new dwarf nova.  Great star for us 
borealites!

It's also time to start up the AM CVn season again.  The 1992-2010 data
shows a small period decrease pretty clearly (inflection in the O-C), 
but it's small enough that another season, or half season, is really 
needed to mail it down.  Even though CanVen is slightly off season, you 
can still get 5 hour runs on it... and we need *dense* coverage, in 
order to separate the 1028 s signal from the contaminating and slightly 
larger 1051 and 1011 s signals.

If you're in the USA and plan to observe AM CVn in the next 5 nights, 
could you use cba-chat to tell us?  I have an observing run going at MDM 
right now, and have observed the star for 2 nights - I'd like to turn to 
fainter targets if possible (more suited to a 1.3 m telescope), but will 
only do so if I'm pretty sure someone else is doing it.

joe

-------- Original Message --------
Subject: new SU UMa candidate
Date: Wed, 5 Jan 2011 09:01:31 +0100
From: Enrique de Miguel Agustino <demiguel at uhu.es>
To: Joe Patterson <jop at astro.columbia.edu>

Hi Joe,

  Just want to call your attention on this apparently SU UMa candidate,
SDSS J114628.80+675909.7 in Dra.
Jeremy Shears had reported (VSNet) a brightening of this object that
could point to an outburst (~1 hour run on 3 Jan). I run afterwards
(~1.5 h)
and it exhibited very small sort of superhumps (full amplitude ~0.08
mag).
But tonight it's clearly in superoutburst, with full ~0.4 mag amplitude
superhumps and Psh=0.0615(8) d. It has reached a max Vmag of
15.00. I've sent the data to the CBA database as well as to
Jeremy.

   References for this object:

- Downes:  CV/UG object with unkown range and no further info.
- Szkody et al AJ 126, 1499 (2003). Supected DN with typical
    low-Mdot DN spectrum that points to SU UMa-type. From velocity
    curves, P_orb ~ 1.6 h = 0.0667 d.
- International Variable Star Indes (VSX), UG type with max mag
    16.9.
- Ritter and Kolb (RKcat7.14, 2010) doesn't give any further info.


  This object may well be of interest to other CBAers, as it has been
caught
at the very beginning of the superoutburst, and is well placed for long
time series (Northerners). Among other things, it appears that P_sh is
(significantly) smaller than Porb, though I'm not sure about the
uncertainty on the latter.

  Regards .... and all the best for 2011 (a bit late, I guess....)

Enrique