Mask Halpha in sky spectrum

[ajmejia]

Masks Halpha in sky spectrum to avoid geocoronal subtraction.

[kslong]

Am I correct in understanding what this does is add an extra step to sky subtraction. One creates the sky as at his been previously, but then one interpolates over the the wavelength range 6559 6566. Are we sure there are no other airglow lines close to Ha that would be expected.

[kreckel]

I don't see any blending of any OH lines with Ha in those wavelengths, you can see this plot on the geocoronal page:

https://sdss-wiki.atlassian.net/wiki/download/thumbnails/14459069/geocoronal_example_spec_fit.png?version=1&modificationDate=1720773904884&cacheVersion=1&api=v2&width=1280&height=583

I guess there is a small chance that something is overlapping exactly? But from talking with Amy there's no evidence a line like this exists

[kslong]

I looked at my own plots of this region, and I do agree with @kreckel that with these limits one is basically OK with respect to sky subtraction. If we are going to interpolate across this region. Is the ultimate intention to simply use the "continuum" as the sky for this region, or are we going to take the sky and try to interpolate across?

• The danger of using the "continuum" is that it depends on the continuum separation to be accurate
• The danger of interpolating is just that outside the region above there are definite sky lines, so one needs to be careful.

If someone could describe the exact plan. I can easily test it.