From the IAU Circular No. 6655, 1997 May 11, (C) Copyright 1997 CBAT:

S. G. Djorgovski, M. R. Metzger, S. C. Odewahn, R. R. Gal, S. R. Kulkarni, 
and M. A. Pahre, California Institute of Technology (CIT); D. A. Frail, 
National Radio Astronomy Observatory; and E. Costa, M. Feroci, and the rest 
of the BeppoSAX team, write:  "We have obtained deep optical images of the 
field of GRB 970508 at the Palomar 5-m and 1.5-m telescopes on May 9, 10, 
and 11 UT. Bond's optical variable is measured at R.A. = 6h53m49s.43, 
Decl. = +79o16'19".6 (equinox 2000.0), with uncertainties of 1".  Our
preliminary reductions indicate that the source had Gunn r magnitudes of 
21.33, 20.17, and 20.15 on May 9.19, 10.23, and 11.21, respectively, 
corresponding to fluxes f(nu) of 11.1, 32.2, and 32.8 microJy at the 
effective wavelength of 665 nm (estimated total errors of 10-20 percent).  
The Gunn colors measured on May 10.23 were g-r = -0.01 and r-i = +0.02, 
which can be fitted with a power- law slope of about -0.5 in f(nu) vs. nu, 
with large errors.  No other significantly variable sources brighter than 
r about 23 have been detected in the revised GRB error circle." 

Metzger, Djorgovski, C. C. Steidel (CIT), Kulkarni, K. L. Adelberger (CIT), 
and Frail further write:  "Spectra of Bond's variable were obtained using 
the Keck II 10-m telescope (+ LRIS) on May 11.25 UT.  The object has no 
obvious emission lines.  We have identified a set of aborption features 
between 430 and 514 nm that we associate with the Fe II triplet near 237.5 nm, 
Fe II at 258.6 and 260.2 nm, and Mg II at 279.6 and 280.3 nm, which places 
this system at z = 0.835.  Several other absorption features are also seen.  
If the source is associated with GRB 970508, it is evident that the gamma-ray
burst lies at z >/= 0.835.  Absence of prominent Lyman-alpha forest in the
spectrum also suggest that the source is at redshift z < 2.1." 



From the IAU Circular No. 6658, 1997 May 12, (C) Copyright 1997 CBAT:

S. G. Djorgovski, S. C. Odewahn, R. R. Gal, M. R. Metzger, S. R. Kulkarni, 
and M. A. Pahre, California Institute of Technology; D. A. Frail, National
Radio Astronomy Observatory; and E. Costa, M. Feroci, and the rest of the
BeppoSAX team write:  "Observations at Palomar indicate that the optical
counterpart of GRB 970508 (IAUC 6654, 6655) has began to decline in 
brightness, as shown by the following Gunn r-band magnitudes:  May 9.195 
UT, 21.2 +/- 0.15; 10.178, 20.18 +/- 0.07; 11.198, 20.16 +/- 0.06; 12.195,
20.53 +/- 0.06.  It had apparently gone through a peak brightness some time 
on May 10, and is now fading.  Such lightcurve behavior is expected in some
classes of theoretical models. 



From the IAU Circular No. 6660, 1997 May 13, (C) Copyright 1997 CBAT:

S. G. Djorgovski, M. R. Metzger, S. R. Kulkarni, S. C. Odewahn, R. R. Gal, 
and M. A. Pahre, California Institute of Technology; D. A. Frail, National 
Radio Astronomy Observatory; E. Costa and M. Feroci, and the rest of the
BeppoSAX team write:  "Observations at Palomar indicate that the optical
counterpart of GRB 970508 is continuing to decline in brightness; on May 
13.18 UT, its Gunn r-band magnitude was 20.76 +/- 0.15.  We also detect a 
faint blue galaxy with r = 24.8 and g = 24.4, located about 4".3 east and 
3".5 north of the variable.  The two may be associated, and/or the galaxy 
may be responsible for the absorption lines seen in the spectrum of the 
object at z = 0.835 (IAUC 6655).