[Aavso-photometry] GJ 436 Campaign Web Page

[arne]

Wolfgang Renz wrote:
> Hi Arne
> 
> Does the 15arcsec companion of the 114 comp also have BVRcIc data ?
> Then the ones with wide-field setups and low resolution might be able to
> subtract it out if it can not be resolved well.
> (haven't seen a SRO calibration file for GJ 436 or ASAS 182611+1212.6 yet)
> 
All of my Sonoita Research Observatory (SRO) calibrations
are dynamically available on the web at:
ftp://ftp.aavso.org/public/calib/master_sro.dat
This file is updated every time we get another calibration night.
This flat ASCII file format will change slightly in about a month,
and a relational database containing this information along
with my NOFS calibrations will be available in late-summer.
Both GJ436 and ASAS182612 are present in that file.  I'm doing
so much calibration work that I've given up on splitting off
individual fields as separate files except in a few instances.

In master_sro.dat, the companion is listed as

175.554889  26.770939 11:42:13.17  +26:46:15.4  J2000
   V     B-V    V-Rc   Rc-Ic  V-Ic
16.222  0.655  0.322  0.619  0.790
but with large error, as it is on the faint end of the
calibration dynamic range.  Since it is about 5 magnitudes
fainter than the 114 star, it will contribute about 0.01mag
to the total flux.  You should either always include it or
always exclude it in your photometry.  The worst case is if
you used an aperture with about 15arcsec radius, as you would
erratically include the star, affecting your photometry at
the 0.01mag level; the same range as the transits you are
trying to measure!
Arne