Re: V1687 Cyg
Posted: Mon Aug 29, 2016 5:16 pm
Hi Fran,
We will be looking for quite small changes superimposed on the top of the lines and the star will be at quite low elevation around periastron from here so getting even relative flux calibration with high enough accuracy to measure the changes is potentially tricky. This was also the case last periastron. Fortunately the problem can be avoided by rectifying the spectra to remove the continuum shape using the same pseudo-continuum points that Marchenko used (see my post above). The changes during periastron were then extracted by subtracting the mean spectrum outside periastron. I remember there were some discussions about whether an instrument response correction using a reference star was even necessary since the spectrum was going to be rectified, but I did it for my results any way.
Here is the link to the paper produced last periastron which describes the data reduction and the measurements made on the spectra
http://cdsads.u-strasbg.fr/cgi-bin/nph- ... 8....2F&db
The PIs Tony Moffat and Noel Richardson monitor the Convento group list and would probably respond to any questions on the campaign there but note many on that list are pro astronomers who expect the "signal/noise" on the list to be kept high.
Cheers
Robin
We will be looking for quite small changes superimposed on the top of the lines and the star will be at quite low elevation around periastron from here so getting even relative flux calibration with high enough accuracy to measure the changes is potentially tricky. This was also the case last periastron. Fortunately the problem can be avoided by rectifying the spectra to remove the continuum shape using the same pseudo-continuum points that Marchenko used (see my post above). The changes during periastron were then extracted by subtracting the mean spectrum outside periastron. I remember there were some discussions about whether an instrument response correction using a reference star was even necessary since the spectrum was going to be rectified, but I did it for my results any way.
Here is the link to the paper produced last periastron which describes the data reduction and the measurements made on the spectra
http://cdsads.u-strasbg.fr/cgi-bin/nph- ... 8....2F&db
The PIs Tony Moffat and Noel Richardson monitor the Convento group list and would probably respond to any questions on the campaign there but note many on that list are pro astronomers who expect the "signal/noise" on the list to be kept high.
Cheers
Robin
