Subject:

From: Daniel Reichart

Submitted: Sat, 23 Jan 1999 21:50:37 -0600 (CST)

Message number: 24 (previous: 23, next: 25 up: Index)

Hi again, 

Just a quick addendum.  One of the scientific justifications for doing this 
sort of observation is to get a good measure of the extinction spectrum of the 
host galaxy.  The steep spectral index (-1.75) suggests that the intrinsic 
spectrum (which typically has a spectral index of > -1) might be extincted.

Such afterglows of moderate extinction (such as GRB 971214) are valuable links 
between afterglows of very low extinction (such as GRB 97508) and those 
afterglows that lack an optical afterglow altogether, possibly due to 
extinction.

In addition, much can be learned from the extinction spectrum itself.  Star 
formation greatly affects the nature of the extinction spectrum.  For example, 
within our galaxy and the Magellanic clouds, one can distinguish between an 
early-type and a late-type starforming region from the extinction curve alone.

Given the theoretical association of GRBs with star formation, these types of 
observations - multiband photometry - are extremely valuable.

Cheers, 

Dan


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