[vsnet-obs 64052] Re: [AVSON] SW Crt

[arne]

Rod Stubbings wrote:
> Hi All,
> 
> SW Crt is classifed as a UGZ: 15.2-17.2p. Downes list it as a non-cv. Since
> the alert on SW Crt I have paid more attention on this star and noticed a
> variation of about 0.7 mag over 6 hours. The range is from15.0 to 15.8 so it 
> is quite faint.
> As there is no sequence all estimates were by eyeball but the variation is 
> there.
> Stan Walker has sent a excel spreadsheet on my obs which I have uploded to
> the AVSON files area. Stan has suggested at this stage it would be usefull
> for some CCD measures and a set of UBV measures as the U-B colour will tell
> if it is a CV. So can anyone help with this star.
> 
At -24dec, SW Crt is not scheduled for calibration by APASS until this
time next year.  Therefore, I'll put it on the SRO calibration queue to
get covered in the next few days.

U-band is a different story.  The star itself will be around 15th, and
while we can do U-band at Sonoita, getting high enough precision to get
a good (U-B) color index at this faint magnitude at high airmass
is not easy.  With luck, MJUO will be operational in time to catch
it this season.  Let's see what BVRI tells us.

Christlieb et al. list SW Crt as a field horizontal-branch star based
on objective-prism spectroscopy, and it is at +36deg galactic
latitude (out of the plane).  My guess is that this is just an
RR Lyr star.
Arne