GRB 050219A

P. Schady (MSSL), M. Ivanushkina (PSU), T. Poole (MSSL), C. Gronwall (PSU), 
A. Blustin (MSSL), P. Brown (PSU), S. Rosen, K. McGowan, M. De Pasquale 
(MSSL), P. Boyd (GSFC/UMBC), S. Holland, M. Still (GSFC/USRA), W. Landsman 
(GSFC), S. Hunsberger (PSU), A. Breeveld (MSSL), P. Roming (PSU), K. Mason, 
H. Huckle (MSSL), P. Broos (PSU), T. Kennedy, P. Smith, B. Hancock (MSSL), 
S. Koch (PSU), M. Carter (MSSL),  J. Racusin (PSU), E. Fenimore (LANL), B. 
Zhang (UNLV), J. Nousek (PSU), N. Gehrels (GSFC), on behalf of the Swift 
UVOT team.

The Swift Ultra-Violet/Optical Telescope (UVOT) began observations of 
GRB050219a on February 19, 2005, at 12:41:21 UT, 80 seconds after the 
initial Swift BAT trigger (Hullinger et al, GCN 3038
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 ).  We detect no source 
at the Swift XRT position (Romano et al, GCN 3036
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 ).  The limiting 
magnitudes in each of the UVOT filters are as follows:

  UVW2 ~ 21.0 (3-sigma) for a combined 277 second exposure starting @ 80 
seconds after the burst
  UVM2 ~ 20.8 (3-sigma) for a combined 277 second exposure starting @ 201 
seconds after the burst
  UVW1 ~ 21.7 (3-sigma) for a combined 287 second exposure starting @ 216 
seconds after the burst
  U ~ 21.6 (3-sigma) for a combined 280 second exposure starting @ 230 
seconds after the burst
  B ~ 21.5 (3-sigma) for a combined 278 second exposure starting @ 245 
seconds after the burst
  V ~ 20.7 (3-sigma) for a combined 374 second exposure starting @ 96 
seconds after the burst

We caution that the instrument is not yet fully calibrated and that the 
magnitude limits presented here may need to be refined.

K. L. Page, M. R. Goad, O. Godet, J. P. Osborne,  (U. Leicester), M. Perri 
(ASDC), J. L. Racusin, D. N. Burrows, (PSU), C. Pagani, G. Tagliaferri 
(INAF-OAB), V. Mangano (INAF-IASF/Palermo), K. Hurley (UC-Berkeley), N. 
White, N. Gehrels (GSFC), B. Zhang (U. Nevada), report on behalf of the 
Swift XRT team:

We report a refined XRT position for GRB 050219a (Romano et al. 2005, GCN 
3036
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 ; Hullinger et al. 2005, GCN 3038
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 ), based on ground-processing of XRT 
Photon-Counting mode data taken during the first orbit after the 
burst.  The refined position is:

RA(J2000) = 11:05:38.8,
Dec(J2000) = -40:40:58.3.

We estimate an uncertainty of about 6.3 arcseconds.

The lightcurve of this burst is fading, with a steep power-law up to about 
200 s post-burst and a shallower power law at later times.

Swift observations of this burst ended at 21:05:36.00 UT, when the Swift 
BAT triggered on GRB 050219b, which replaced GRB 050219a as the new GRB 
target in the on-board schedule.

A. de Ugarte Postigo (IAA-CSIC, Granada),
S. Eguchi (Stelab, Nagoya Univ.),
J. Gorosabel (IAA-CSIC), Ph. Yock
(Univ. of Auckland) and  A.J. Castro-Tirado
(IAA-CSIC), report:

"Following the detection by SWIFT of GRB
050219a (Hullinger et al. GCN Circ. 3038
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 )
we imaged the error box with the 0.6 m
telescope at Mt. John Univ. Observatory.
We obtained 3 x 300s images with the MOA
camera (+ wide R-band filter) under poor
seeing conditions (4"- 5") starting on
19.613 Feb (i.e. 2.05 hr after the event).
Additional observations were performed with
a wide B-band filter. Comparison of the
stacked R-band image with the DSS-2 revealed
neither counterpart within the 6" radius 
X-ray afterglow position given by the 
SWIFT/XRT (Romano et al. GCN Circ. 3036
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 ) 
nor variable source to about R = 20.5 within 
the 4' radius SWIFT/BAT error box."

E. Berger (Carnegie Observatories) and S. Gonzalez (Las Campanas
Observatory) report:

"We imaged a field centered on the XRT error circle (GCN 3040
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 ) of GRB
050219a (GCN 3038
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 ) with the Las Campanas Observatory's Swope 40-in
telescope in the I-band for a total of 20 min (2005, Feb 20.264, 17.7
hours after the burst). We do not detect any sources within the 6.3 arcsec
radius XRT error circle to a limit of about 21.5 mag."