(cba:news) New and old DQ Hers, plus wannabes
jop at astro.columbia.edu
Thu Jan 16 08:28:50 EST 2014
Lots of clear weather in AZ, and we seem to be spending a lot of time on
DQ Her stars and candidates.
1. HZ Pup has a great light curve, but we lack the off-longitude data to
nail the periods down. Also, we've stopped observing it, so time series
from the Americas are now plenty helpful too. Around mag 16.5.
2. PBC J0706.7+0327 (7h6m48.89s +3d24m45.0s) is a peachy candidate DQ:
possible period near 5 minutes. Around mag 17.
3. Swift J0503.7-28 (5h3m49.2s -28d23m9s) looks promising too; not as
swift as PBC0706, but sumpin' near 16 minutes. Around mag 17. In
Caelum. I always wondered why such a miserable little constellation had
such a regal name (heaven) - but apparently it just means "chisel".
4. V455 And. Kinda late for Andromeda, but we're building a nice record
of the 67/34 s oscillations, which will be ideal for a test of their
stability. Our run ends on Sunday. If you can possibly resolve at
least one of these signals (total cycle time less than 15-20 s), the
timing data would be great.
5. The bible for these stars is Koji Mukai's page:
I can't stress this (website) enough. The most promising
not-yet-credentialed stars, feasible for CBA tracking, are FS Aur,
Paloma (0524+42) and GI Mon. The most promising for tracking the known
spin pulse are DW Cnc, WX Pyx, and EX Hya. And, in general, Koji's
website is a great place to sniff around in.
Although you might think you need long integrations to get good S/N near
mag 17, remember that the main enterprise is period-finding, which
depends much more on cumulative S/N. The light curve might have an ugly
0.1 mag noise band superimposed on it, plus intrinsic flickering
noise... yet still easily detect a signal of 0.02 mag. For the most
famous periodic variable in the sky, the Crab pulsar, most integrations
in radio/optical/X-ray light yield ZERO photons, corresponding to zero
S/N and magnitude infinity; but in a few seconds or tens of seconds, the
period comes roaring through.
Corinthians says that three things last forever: faith, hope, and love.
Love is obvious: you have to love night-sky observing and trolling for
periodic signals, or you wouldn't be reading this. Likewise for hope -
why else suffer the indignities of observing? And after some experience
squinting at these little wiggles in light curves and pressing buttons
on laptops, you develop some serious faith.
Center for Backyard Astrophysics (CBA) mailing lists
More information about the cba-public