[vsnet-chat 1742] Re: BVRI Photometry

[aah@nofs.navy.mil]

Another suggestion for those attempting to measure bright
variables without nearby bright comparison stars.  One
project I'm working on with Ray White (UofA) is to monitor
about 30 bright RR Lyrae stars, looking for period changes
(like Stan with his Cepheids).  Many of these fields have
no bright comparison stars.  What I do for them is to use
the fainter stars as an 'ensemble' to obtain a zero point
for the field.  Even though an individual star might have
Poisson errors of 5-10 percent, if you average enough of
them, you beat the errors down by root(n).  This was
described in a PASP paper by Honeycutt a few years ago.
Unlike visual observing, CCDs are linear and you can use
faint stars to calibrate bright ones.
Arne

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp