ISIS b-v values

[Robin Leadbeater]

During reduction, ISIS generates b and v values for each exposure but I cannot find any information on what they are or what they are used for

iis_b-v_values.png (5.83 KiB) Viewed 3755 times

Are they the mean intensity in the standard photometric b, v passbands?

Thanks
Robin

[Robin Leadbeater]

Anyone ?

[Joan Guarro Flo]

Hi Robin,
You're not alone
Yes, what and I'm, but I don't understand and I don't know the answer.

Friendly, Joan.

[Christian Buil]

Robin,

(b) - (v) information is indicative of the impact of atmospheric chromatism (or telescope chromatism) on the spectrophometric quality of the collected data in a sequence of spectra.

This situation is explained for many examples on the web page (in French sorry):

http://www.astrosurf.com/buil/dispersion/atmo.htm

(some time dramatic !)

It is an arbitrary parameter that allows to reject some very affected spectra. This is the case of spectra whose index (b) and (v) (relative intensities) deviate much from the average or median value of a sequence.

Christian B

[Robin Leadbeater]

Thank you Christian,

This could be useful now for V392 Per which is very low. There are some big variations in the continuum of the published spectra.

Cheers
Robin