search

StellarCartography / pydis

DEPRECATED: Check out PyKOSMOS!
https://github.com/jradavenport/pykosmos
MIT License
43 stars 27 forks source link

flux calibration unstable at the edges #59

Open migueldvb opened 8 years ago

migueldvb commented 8 years ago

I have tried to run flux calibration in pydis using the standard star G191b2b. These data cover the optical and near-UV region starting around 3000 Å. The sensitivity function using the IRAF libraries blows up at the blue end as shown in the figure below.

figure_1 figure_1-1 figure_1-3

If the standard star spectrum is clipped to start around 3200 Å the result is better but when the sensitivity function is applied to the standard star data the result still is as shown in the figure below. Is this a problem with the interpolation in DefFluxCal?

figure_1-5

jradavenport commented 8 years ago

Hm, I'm not sure I understand this either. Can you remind me what the last figure is showing? Is this an issue of extending the fit past the IRAF reference spectrum? This is a tricky issue, as it does try to smoothly extend it if needed.... which is dangerous!

migueldvb commented 8 years ago

In the last figure the red dots are the standard flux from the IRAF library and the black line is the observed standard with applied sensitivity function. The IRAF reference spectrum starts at 3200 Å so I have tried to clip the observed spectrum at 3300 Å but still this problem is present at the edge. I was wondering if you have noticed something similar with other standard stars.

jradavenport commented 6 years ago

I wonder if this would be fixed by #71...