GCN Circular 8712

Alice Breeveld (MSSL), Wayne Landsman (GSFC), Paul Kuin (MSSL) and  
Dirk Grupe (PSU) report on behalf of the Swift/UVOT team:

Further analysis of Swift/UVOT data of GRB081222 (Grupe et al., GCN  
Circ. 8691
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 ), shows that the burst was detected in the v and b filters  
in addition to the white and u filters described in the initial  
circular (Breeveld et al., GCN Circ. 8696
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 ). The source is not detected  
in any of the UV filters, in single or co-added exposures. The initial  
magnitudes and upper limits are given in the table below:

Filter    Tstart(s) Tstop(s)     Exp(s)   Magnitude
white   60            210           147        14.84+/-0.02
white   873          1023         147       17.36+/-0.03
v           602          622           20          16.20+/-0.02
b           528          548           20          16.86+/-0.02
u           272           522           246       16.32+/-0.03
uvw1    652          1815         142        >20.9  (3-sigma UL)
uvm2    627          1790         127        >21.0  (3-sigma UL)
uvw2    577          1914         124        >21.1  (3-sigma UL)

A 49s UV grism spectrum was obtained beginning 216s after the  
trigger.  The very low S/N quicklook spectrum shows a continuum of  
about 3e-15 erg/s/cm2/A longward of ~3400 A.  No flux is detected  
shortward of 3400 A, even though the grism sensitivity increases  
toward shorter wavelengths.  If this is the wavelength of the Lyman  
edge, then the redshift of GRB081222 is ~2.7.  The detection of  
GRB081222 in the u filter and the non-detection in UVW1 filter are  
consistent with this redshift.

The values quoted above are in the UVOT photometric system (Poole et  
al. 2008, MNRAS, 383, 627) and are not corrected for the expected  
Galactic extinction corresponding to a reddening of E(B-V)=0.021 mag  
in the direction of the burst (Schlegel et al. 1998).