TITLE:   GCN CIRCULAR
NUMBER:  28662
SUBJECT: GRB 201015A: Swift/UVOT Detection
DATE:    20/10/16 20:49:02 GMT
FROM:    Frank Marshall at Swift/UVOT  <marshall@milkyway.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC) and V. D'Elia (SSDC)

report on behalf of the Swift/UVOT team:



The Swift/UVOT began settled observations of the field of GRB 201015A

3217 s after the BAT trigger (D'Elia et al., GCN Circ. 28632).

A weak source consistent with the optical position

(Malesani et al. GCN Circ. 28637)

is detected in the initial UVOT exposures.



Preliminary detections and 3-sigma upper limits using the UVOT photometric system

(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:



Filter         T_start(s)   T_stop(s)      Exp(s)           Mag



white             3217         3367          147         20.69 +/- 0.28

white             4402         4602          197         20.33 +/- 0.16

v                 3375         4949          331        >19.3

b                 4197         4397          197         20.47 +/- 0.33

u                 3991         4191          197        >19.7

w1                3786         3986          197        >19.3

m2                3579         3779          197        >18.8

w2                4608         4808          197        >19.4



The magnitudes in the table are not corrected for the Galactic extinction

due to the reddening of E(B-V) = 0.34 in the direction of the burst

(Schlegel et al. 1998).