GRB 050215B

S.A. Yost, D.A. Smith, and E.S. Rykoff report on behalf of the ROTSE
collaboration:

ROTSE3B, located at McDonald Observatory, Texas, responded to GRB050215B
(Swift#0106107) under fair conditions (low elevation). An automatic
response (interrupting the sequence for 050215A) resulted in a sequence of
60+ images beginning 8 sec after the trigger. The first image was taken at
02:35:19.0, 97 sec after the burst. We took 10 5 sec, 10 20 sec, and 40+
60 sec exposures. The images are unfiltered and were calibrated relative
to USNO A2.0.

Individual images have limiting magnitudes from 16-17.7 mag. Comparison to
the DSS reveals no new sources within the 3-sigma error circle to a
limiting magnitude of 17.8-18.8 for coadded sets of 10 images between 100
sec and 50 min post-burst

This message may be cited

Martin Jelinek, Javier Gorosabel, Alberto J.
Castro-Tirado, Antonio de Ugarte Postigo, (IAA CSIC,
Granada), Petr Kubanek, Rene Hudec (ASU AV CR Ondrejov)
and Stanislav Vitek (FEL CVUT Praha). report:


We have imaged the error box of Swift's GRB 050215b
[trigger #106107], with the BOOTES-1B facility in
southern Spain. Comparison with the GSC-2 catalogue does
not reveal any new source. We report the following
3-sigma magnitude limits 25.6 minutes (mean obs. time)
after trigger:

	V > 16.5  
	I > 15.0

on our 600s exposures. 

[GCN OPS NOTE (15feb05):  Per author's request, the 050215c was changed 
to 050215b (since the HETE trigger earlier turned out to not be a real GRB.)]

P. Roming (PSU), K. Mason, P. Schady (MSSL), M. Ivanushkina (PSU), T. Poole 
(MSSL), C. Gronwall (PSU), A. Blustin (MSSL), P. Brown (PSU), P. Schady, 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), S. Koch (PSU), M. Carter, H. Huckle (MSSL), P. Broos (PSU), T. 
Kennedy, P. Smith, B. Hancock (MSSL), J. Kennea (PSU), J. Cummings (GSFC), 
T. Sakamoto  (GSFC), J. Nousek (PSU), N. Gehrels (GSFC), on behalf of the 
Swift UVOT team.

The Swift Ultra-Violet/Optical Telescope (UVOT) began observations of 
GRB050215b (GCN 3024
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 ) on February 15, 2005 at 02:35:10 UT.  We detect no 
source down to a magnitude of 19.5 in the V-filter for a 100 second 
exposure 1747s after the BAT trigger.  No source was detected in the other 
UVOT filters.  The limiting magnitudes in each of the UVOT filters are as 
follows:

  UVW2 = No source identified down to 19.2 (3-sigma) for a 10 second 
exposure @ 88 seconds after the burst
  UVM2 = No source identified down to 21.3 (3-sigma) for a 100 second 
exposure @ 1853 seconds after the burst
  UVW1 = No source identified down to 20.2 (3-sigma) for a 100 second 
exposure @ 1959 seconds after the burst
  U = No source identified down to 19.8 (3-sigma) for a 100 second exposure 
@ 2065 seconds after the burst
  B = No source identified down to 19.9 (3-sigma) for a 100 second exposure 
@ 2171 seconds after the burst
  V = No source identified down to 19.5 (3-sigma) for a 100 second exposure 
@ 1747 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 at a future date.

K. Page (U. Leicester), G. Tagliaferri, S. Campana, A. Moretti, C. 
Pagani,  P. Romano, G.
Chincarini (OAB), G. Cusumano, V. Mangano, V. La Parola (IASF/Palermo), D. 
N. Burrows, J. Kennea, J. E. Hill, J. A. Nousek (PSU), J. P. Osborne, M. 
Goad, A. Beardmore, A. F. Abbey, A. A. Wells (U. Leicester), P. Giommi, M. 
Capalbi, M. Perri, F. Tamburelli (ASDC), T. Sakamoto, L. Angelini, N. 
Gehrels (GSFC), W. Voges (MPE), L. Cominsky (Sonoma State U.), M. Tripicco 
(GSFC-SSAI), report on behalf of the Swift XRT team:

The Swift BAT instrument detected GRB 050215b at 02:35:00 UT on 15 Feb 2005.
The observatory executed an automated slew to the BAT position, but the XRT 
was in Manual State collecting calibration data and did not perform its 
normal automated GRB observing sequence.  Furthermore, the satellite 
entered the SAA shortly after detecting this burst, and the XRT had data 
collection disabled until it exited the SAA at 03:03 to 03:10 UT, at which 
time the XRT was in Manual state and made observations in Windowed Timing 
(WT) mode.  On the second orbit XRT collected data from 04:11 to 04:15 in 
Photon Counting (PC) mode, and from 04:44 to 04:47 in WT mode.  (In between 
Swift was again located in the SAA).  Observations continued in both WT and 
PC modes on subsequent orbits.  With three orbits of PC mode data processed 
through the ground software, we find a faint, uncataloged X-ray source 
located 35 arcseconds from the BAT position at

RA(J2000) = 11 37 46.1, Dec(J2000) = +40 47 54.3.

The XRT alignment calibration is still in progress.  We estimate a systematic
uncertainty in this position of 6 arc seconds radius.

However, the lightcurve of this source, in both WT and PC mode, does NOT 
appear to be fading, although the source is extremely weak and the 
statistics are not good enough yet for an accurate 
determination.  GRB050215b remains the Swift Automated Target, and we 
expect to continue monitoring operations for the next 12 hours.

N. Tanvir, R. Priddey, M. Hughes, S. Pak, R. Chapman (U. Hertfordshire),
P. O'Brien, A. Levan (U. Leicester), C. Simpson (U. Durham),
T. Carroll (JACH) report on behalf of a larger collaboration:

We observed the Swift/BAT position reported for GRB 050215B
with the UFTI camera on UKIRT in good seeing.  The exposure was in
the K98 filter beginning at Feb 15.51 UT (9.76 hours post burst).

We find no sources apart from the bright 2MASS star (catalogued
position 11 37 46.50 +40 47 58.2) within 15 arcsec of the Swift/XRT
position reported by Page et al. (GCN circular 3027
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 ), down to a
limiting K-band magnitude of approx 20.5 (5 sigma).

Preliminary standard star calibration gives a magnitude for the
2MASS star of K=15.4 compared to a catalogued value of 15.22.

This message may be cited.

M. Jelínek, A. J. Castro-Tirado, J. Gorosabel, 
 A. de Ugarte Postigo (IAA-CSIC Granada), 
 P. Kubanek, R. Hudec (Astronomical Institute 
 of the Academy of Sciences, Ondrejov), 
 T. J. Mateo Sanguino (Universidad de Huelva), 
 T. Soria, R. Fernández (EELM-CSIC, Málaga) and 
 J. Fabregat (Universidad de Valencia)
 
 report:
 
 The BOOTES-2 very wide field camera, located at the 
 Estación Experimental de La Mayora (EELM-CSIC) in 
 Málaga, observed the region of the sky containing the 
 SWIFT/BAT error box for GRB 050215b (Barthelmy et al. 
 GCN 3024
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 ) as part of its routine observing schedule. 
 A 30 s exposure started at 02:33:05 UT (7 s prior to 
 the onset of the 10 s long burst), with the following 
 frame starting at 02:34:05 UT. Limiting (unfiltered) 
 magnitude of 10.0 is derived for any prompt optical 
 flash arising from this event.
 
 This message can be quoted.

P.S. Chiang, K.Y. Huang, W.H. Ip (NCU), Y. Urata, T. Tamagawa (RIKEN),
Y. Qiu (BAO), Y.Q. Lou(THCA) on behalf of the East Asian collaboration
report:

 We observed the SWIFT/BAT error region for GRB 050215b ( Barthelmy et
al. GCN 3024
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 ) using Lulin 1-m telescope at Taiwan. We imaged a V-band
300 sec exposure at 15.65 UT (~ 13.07 hrs after the burst ) and a
I-band 300 sec at 17.14 UT ( ~ 14.56 hrs after the burst ). No new
source was found around X-ray source reported by Page et al. (GCN
3027
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 ) at our two observations. Compare with USNO-B1 I band stars, the
limiting magnitudes are V ~ 19 and I ~ 20 (3 sigma).

This message may be cited.

N. Tanvir, S. Pak, R. Priddey, M. Hughes (U. Hertfordshire),
E. Rol, A. Levan, P. O'Brien (U. Leicester), C. Simpson (U. Durham),
E. Vardoulaki (U. Oxford), T. Carroll (JACH) report on behalf of a
larger collaboration:

We have obtained a second epoch of UKIRT/UFTI K-band imaging of
the Swift/BAT position reported for GRB 050215B.  Seeing was
again good (approx 0.5 arcsec compared to 0.4 arcsec on the
previous night).  The observation began at Feb 16.49 UT, roughly
34 hrs post burst.

We find no variable sources within the XRT error circle for the object
reported by Page et al (GCN circular 3027
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 ). However we find a faint,
apparently variable, point source about 30 arcsec from the centre of the
BAT error circle.  It has magnitude K=20.23+-0.11 on night 1 and
K=20.75+-0.22 on night 2 (both measured in a 0.9 arcsec aperture),
which we believe is therefore a good candidate for the afterglow of
this burst.

Although near the detection limit, the source on the second night
may be slightly extended (possibly also on the first), which would
indicate a host contribution, and hence that particularly the second
magnitude should be treated as an upper limit on the afterglow
magnitude.

The location of this object, is 15.7 arcsec E and 12.7 arcsec S
of the 2MASS/USNO-B1 catalogued object (whose magnitude we refine to
K=15.46 based on our standard star calibration).  ie. in the USNO-B1
system the candidate afterglow is located at:

 11:37:47.90 40:47:45.6

Postage stamp images are available on:

  http://star-www.herts.ac.uk/~nrt/050215b.html

Further followup is ongoing.

M. Goad, K. Page, J. P. Osborne, P. O'Brien (U. Leicester), D. C. 
Morris,  J. A. Kennea, D. N. Burrows, J. L. Racusin, J. E. Hill, M. M. 
Chester, J. A. Nousek (PSU), P. Giommi, M. Capalbi, M. Perri, F. Tamburelli 
(ASDC), P. Romano, G. Tagliaferri, S. Campana, A. Moretti, C. Pagani,  G. 
Chincarini (INAF-OAB), G. Cusumano, V. Mangano, V. La Parola 
(INAF-IASF/Palermo), A. A. Wells (U. Leicester),  B. Zhang (U. Nevada), T. 
Sakamoto, L. Angelini, N. Gehrels (GSFC), W. Voges (MPE), L. Cominsky 
(Sonoma State U.), M. Tripicco (GSFC-SSAI) report on behalf of the Swift 
XRT team:

The Swift XRT has continued to  monitor the X-ray source (designated SWIFT 
J113746.1+404754) discussed in GCN 3027
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  (Page et al. 2005) in the field of 
GRB 050215b.  We now have data over two epochs, indicating a decaying light 
curve for this object.

First epoch:
	We obtained 5155 seconds of data in Photon-Counting mode (our most 
sensitive observing mode) from six orbits beginning at 04:09:52 UT on 
2005-02-15.  The average count rate for SWIFT J113746.1+404754 in the first 
two orbits is 0.0231 +/- 0.0050 cps (0.2-10 keV).  The average count rate 
for this source over orbits 3-6 is 0.0108 +/- 0.0018 cps, consistent with a 
decreasing rate.

Second epoch:
	We obtained 1640 seconds on SWIFT J113746.1+404754 between 01:36:37 UT and 
09:39:42 UT on 2005-02-17 in Photon-Counting mode.  The source is 
undetectable in this second epoch, with a 95% confidence upper limit on the 
count rate of 0.0018 cps (0.2-10 keV, calculated using the method of Kraft, 
Burrows, and Nousek 1993, ApJ, 1991, 374, 344).

The fading count rate suggests that this source could be the X-ray 
afterglow of GRB 050215b, although it is extremely weak in the first epoch 
(a few times 10^-13 ergs/cm**2/s at about 95 minutes post-burst).  However, 
we cannot rule out other possibilities.  We note that there is an optical 
source (R=17.3, B=18.5) in the USNO catalog at the edge of the XRT error 
circle of the detected X-ray source reported in GCN 3027
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 .   If we assume 
that this object is the optical counterpart of our X-ray source, the 
optical-to-X-ray ratio is alpha_ox~1.35 during our first epoch, compatible 
with a radio-quiet AGN.  Optical spectroscopy of this USNO object would 
help determine its nature, and could eliminate it from consideration as a 
possible counterpart of SWIFT J113746.1+404754.

We do not detect any X-ray object in either epoch at the position of the 
UKIRT afterglow candidate (Tanvir et al. 2005, GCN 3031
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 ).  We place 95% 
upper limits on the XRT count rate from the UKIRT afterglow candidate of 
0.0006 cps in the first epoch and  0.0018 cps in the second epoch (0.2-10 
keV), within a 20 arcsecond radius circle of the UKIRT position.

Further Swift observations of this field are planned through the weekend.

S. Bradley Cenko and Derek B. Fox report on behalf of the
Caltech-NRAO-Carnegie GRB Collaboration:

We have imaged the field of the Swift GRB050215b with the automated
Palomar 60-inch telescope.  Our first epoch consists of 9 x 120 s
exposures in the Kron R band, taken at a mean time of 12:00 February
15 UT (~ 9.5 hours after the burst).  Our second epoch consists of 5 x
120 s exposures in the Kron R band, taken at a mean time of 6:50
February 17 UT (~ 52.3 hours after the burst).  Both epochs reach a
3-sigma limiting magnitude of R ~ 20.5.

The only source present in either epoch in the XRT error circle (Page
et.  al., GCN 3027
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 ) is the USNO source discussed by Goad et. al. (GCN
3032
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 ).  We find no evidence for any variability in this source (R =
17.23 +/- 0.1 in epoch 1, R = 17.30 +/- 0.1 in epoch 2).

To our limits, we find no optical counterpart to the NIR candidate
proposed by Tanvir et. al. (GCN 3031
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 ) in either epoch.

M. Goad, K. Page, J. P. Osborne, P. O'Brien (U. Leicester), D. C.
Morris,  J. A. Kennea, D. N. Burrows, J. L. Racusin, J. E. Hill, M. M.
Chester, J. A. Nousek (PSU), P. Giommi, M. Capalbi, M. Perri, F. Tamburelli
(ASDC), P. Romano, G. Tagliaferri, S. Campana, A. Moretti, C. Pagani,  G.
Chincarini (INAF-OAB), G. Cusumano, V. Mangano, V. La Parola
(INAF-IASF/Palermo), A. A. Wells (U. Leicester),  B. Zhang (U. Nevada), T.
Sakamoto, L. Angelini, N. Gehrels (GSFC), W. Voges (MPE), L. Cominsky
(Sonoma State U.), M. Tripicco (GSFC-SSAI) report on behalf of the Swift
XRT team:

We confirm that the fading IR object discovered by Tanvir et al. 2005 (GCN 
3031
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 ) is the afterglow of GRB 050215b.

We have discovered an error in the astrometry for previously-reported XRT 
positions on the field of GRB050215b.  This affects both the position 
reported by Page et al. 2005 (GCN 3027
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 ) and some of the information in Goad 
et al. 2005 (GCN 3032
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 ).  We recommend that those GCNs not be referenced, 
and that this Circular be referenced instead for XRT observations of this 
burst.

The corrected XRT position for the afterglow of GRB 050215b is

RA(J2000) = 11 37 47.7 , Dec(J2000) =  +40 47 44.0

The estimated uncertainty in this position is 6 arcseconds radius.  We note 
that this corrected error circle now includes the UKIRT counterpart 
candidate (Tanvir et al. 2005, GCN 3031
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 ).  Further, the new XRT position 
puts the USNO/2MASS object mentioned in GCN 3032
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  outside of the XRT error 
circle.  We can therefore definitely confirm this object as the afterglow 
of GRB 050215b.

We can also now definitely say that the XRT counterpart is fading, but with 
a fairly flat decay curve (slope of -0.76 +/- 0.26).

The Swift XRT has continued to  monitor the X-ray source (now designated SWIFT
J113747.7+404744) discussed in GCN 3027
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  (Page et al. 2005) in the field of
GRB 050215b.  We now have data over two epochs, indicating a decaying light
curve for this object.

First epoch:
	We obtained 5155 seconds of data in Photon-Counting mode (our most
sensitive observing mode) from six orbits beginning at 04:09:52 UT on
2005-02-15.  The average count rate for SWIFT J113747.7+404744 in the first
two orbits is 0.0231 +/- 0.0050 cps (0.2-10 keV).  The average count rate
for this source over orbits 3-6 is 0.0108 +/- 0.0018 cps, consistent with a
decreasing rate.

Second epoch:
	We obtained 1640 seconds on SWIFT J113747.7+404744 between 01:36:37 UT and
09:39:42 UT on 2005-02-17 in Photon-Counting mode.  The source is
undetectable in this second epoch, with a 95% confidence upper limit on the
count rate of 0.0018 cps (0.2-10 keV, calculated using the method of Kraft,
Burrows, and Nousek 1993, ApJ, 1991, 374, 344).


Further Swift observations of this field are planned through the weekend.

[GCN OPS NOTE (18feb05): Per author's request some typos were corrected:
In lines 42 and 55, "J1137477+404744" was changed to "J113747.7+404744".
In line 49 "J113746.1+404754" was changed to "J113747.7+404744".]

A. M. Soderberg (Caltech) and D. A. Frail (NRAO) report on behalf of a
larger collaboration:

"On 2005 Feb 18.5 UT we carried out follow-up observations with the
VLA at 8.46 GHz centered on the optical afterglow candidate (GCN 3031
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 )
of GRB 050215B (GCN 3024
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 ). Within the XRT position circle of 6-arcsec
radius (GCN 3034
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 ) there are no radio sources to a 3-sigma limit of 93
microJy."

K. Mason, 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. T. Holland, M. Still (GSFC/USRA), W. Landsman
(GSFC), S. Hunsberger (PSU), A. Breeveld (MSSL), P. Roming (PSU), M. Carter, H.
Huckle (MSSL), P. Broos (PSU), T. Kennedy, P. Smith, B. Hancock (MSSL), S. Koch,
D. Morris (PSU), S. Barthelmy, T. Sakamoto  (GSFC), J. Nousek (PSU), N. Gehrels
(GSFC), on behalf of the Swift UVOT team.

After further observations of GRB 050215B with the Swift Ultra-Violet/Optical
Telescope (UVOT), we have identified a source near the position identified by
Tanvir, et al (GCN 3031
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 ).  The source was detected at a position of RA =
11:37:48.03 and Dec = +40:47:43.4 (J2000).  The UVOT alignment is not yet fully
calibrated, therefore, we estimate a systematic uncertainty of about +/-
1arcsecond in this position.  Reexamination of the early time UVOT observations
at this location are consistent with our previously reported findings of no
detected afterglow (Roming et al, GCN 3026
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 ).  The source was identified at a
magnitude of 21.7 by co-adding three V-band images which were taken 2.2-9.7
hours after the initial trigger.  Examination of V-band images taken after this
time reveal no reliable detections. We caution that the instrument is not yet
fully calibrated and that the magnitudes presented here may need to be refined.

A. Monfardini (Liverpool), N. Tanvir (Hertfordshire), C. Mundell
(Liverpool), R. Smith (Liverpool), A. Levan (Leicester), E. Rol
(Leicester), P. O'Brien (Leicester) and M. Bode (Liverpool) 
on behalf of the ROBONET collaboration report:

"We observed the field of GRB050215b (GCN 3024
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 ) with the 2.0m Faulkes
North Telescope on Haleakala. We obtained SDSS-I imaging commencing 
1.229 days after the burst under poor seeing conditions. A re-analysis at
the position of the candidate first reported by Tanvir et. al and then
confirmed by XRT (GCN 3031
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 , GCN 3034
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 ) shows no detection on our images up
to I=20.5 (limited by technical problems). 

We reiterate the coordinates:

RA=11:37:47.90   DEC=+40:47:45.6

We also searched for possible hosts in SDSS plates (observations date: 
2003-04-01) and found no candidates within 5 arcsec up to (SDSS filters):

u = 21.0
g = 21.9
r = 22.0  (R ~ 21.9)
i = 21.7  (I ~ 21.3)
z = 20.2
  
These values were derived using SDSS field photometry references."

This message can be cited

HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash

Y. Nakagawa, G. Ricker, J-L. Atteia, N. Kawai, D. Lamb, and S. Woosley,
on behalf of the HETE Science Team;

T. Donaghy, E. Fenimore, M. Galassi, C. Graziani, M. Matsuoka,
T. Sakamoto, R. Sato, Y. Shirasaki, M. Suzuki, T. Tamagawa, Y. Urata,
T. Yamazaki, Y. Yamamoto, and A. Yoshida, on behalf of the HETE WXM
Team;

N. Butler, G. Crew, J. Doty, G. Prigozhin, R. Vanderspek,
J. Villasenor, J. G. Jernigan, A. Levine, G. Azzibrouck, J. Braga,
R. Manchanda, and G. Pizzichini, on behalf of the HETE Operations and
HETE Optical-SXC Teams;

M. Boer, J-F Olive, J-P Dezalay, and K. Hurley, on behalf of the HETE
FREGATE Team;

report:

GRB 050215b (=U11570) occurred 36 degrees off the HETE boresight, and
therefore well within the FREGATE field of view but only at the very
edge of the WXM field of view.  Consequently, the burst is seen in the
FREGATE data but not in the WXM data.

Using a simple power-law model to fit the FREGATE spectral data, we
find a best-fit power-law index of beta = -2.2 (+0.4/-0.6).  Using a
constrained Band model (Sakamoto et al., ApJ, 602, 875, 2004) to fit
the data, we find a best-fit value for the peak energy of E_peak =
17.6 keV; a 68% confidence region 4.8 keV < E_peak < 23.7 keV, a 95%
upper bound E_peak < 30.3 keV, and a 99% upper bound E_peak < 35.7 keV.
Finally, using a Band model with the low-energy power-law index alpha
fixed at -1 to fit the data, we find fluences of S_x (2-30 keV) = 2.8
(+3.3/-1.1) x 10-7 erg cm-2 and S_gamma (30-400 keV) = 1.7 (+2.5/-1.3)
x 10-7 erg cm-2.  The best-fit value of S_x/S_gamma is therefore 1.65.
Taken together, these results are strong evidence that GRB 050215b was
an X-Ray Flash.

We note that a supernova component has not been definitively
established in the afterglow of any X-Ray Flash and that any supernova
component in the afterglow of GRB 050215b would be expected to peak
soon.  We therefore encourage further observations of the afterglow of
this burst.

This message may be cited.

T. Sakamoto, S. Barthelmy, N. Gehrels, J. Cummings, A. Parsons, 
J. Tueller (GSFC), E. Fenimore, D. Palmer (LANL), D. Hullinger, 
C. Markwardt (GSFC/UMD), H. Krimm (GSFC/USRA), G. Sato (ISAS), 
M. Suzuki (Saitama) 

With the further analysis of the BAT spectral data of GRB050215b, 
we confirmed the nature of X-ray flash for GRB050215b.   

If we used the best fit Epeak energy of 17.6 keV derived from the HETE 
data (Nakagawa et al, Circ 3053), the transition energy between the 
lower energy cutoff power-law component and the higher energy power-law 
component of the Band function (Band et al. 1993) will be 26.4 keV if we 
assume alpha=-1 and beta=-2.5.  Based on this estimation, we tried to fit 
the BAT spectrum only using above 30 keV to see the evidence of the 
power-law slope of steeper than -2.  

With this fit, we obtained the best fit power-law index of -2.99 
(-1.02/+0.77; 90% confidence).  The significance in the power-law 
index of steeper than -2.0 is 97%.  This is a strong indication 
that BAT observed the higher portion of the Band function, and the 
Epeak of GRB050215b is indeed below 30 keV.

A. M. Soderberg (Caltech) and D. A. Frail (NRAO) report on behalf of a
larger collaboration:

"On 2005 Feb. 27.09 UT we carried out follow-up observations with the
VLA at 8.46 GHz centered on the afterglow (GCN 3031
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 ,3034
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 )
of XRF/GRB 050215B (GCN 3024
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 ,3053
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 ). Within a circle of 1-arcsec radius
there are no radio sources to a 3-sigma limit of 156 microJy.

No further observations are planned."

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


The Swift Ultra-Violet/Optical Telescope (UVOT) observed the field of the 
X-ray flash GRB050215B (GCN 3024
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 ) between February 25, 2005 and February 
28, 2005 UT.  The 5-sigma limiting magnitudes for each exposure are 
presented below.  We stress that the limiting magnitudes are based on 
ground calibrations and are uncertain by approximately +/-0.5 mag.

#                       Exposure
#   Date (UTC) Time     Time (s)  Filter   Mag
  2005-02-25  15:13:13   1670.52     V     22.2
  2005-02-25  19:52:34   2189.47     B     23.0
  2005-02-25  21:32:35   2068.95     U     22.7
  2005-02-25  23:27:38    985.24     V     21.9
  2005-02-26  02:34:31   1351.94     V     22.0
  2005-02-27  15:20:04   2099.11     B     22.9
  2005-02-28  01:07:03   1620.44     V     22.2
  2005-02-28  10:40:04   1919.99     B     22.9

We find no evidence for a brightening source, such as a supernova 
component, at the location of the afterglow seen by UKIRT (GCN 3031
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 ).