GRB 080430

Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report:

We imaged the field of GRB 080430 detected by SWIFT
(trigger 310613) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 18.8s after the GRB trigger
(7.2s after the notice). The elevation of the field increased from
from 82 degrees above horizon and weather conditions
were good.

We detect a new fading source in the error box given by SWIFT
at the following position (+/- 3 arcsec):

RA(J2000.0) = 11h 01m 14.2s
DEC(J2000.0) +51d 41' 08"

OT was R~16 at 18.8s after GRB.

Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.

N.B. Galactic coordinates are lon=155.5591 lat=+57.8882
and the galactic extinction in R band is 0.0 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

This message may be cited.

51�41'08"

C. Guidorzi (INAF-OAB), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC),
O. Godet (U Leicester), S. T. Holland (CRESST/USRA/GSFC),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
W.L Landsman (GSFC), C. B. Markwardt (CRESST/GSFC/UMD),
K. M. McLean (GSFC/UMD), P. T. O'Brien (U Leicester),
D. M. Palmer (LANL), D. Perez (U Leicester), P. Romano (INAF-IASFPA),
T. Sakamoto (NASA/UMBC), M. Stamatikos (NASA/ORAU),
R. L. C. Starling (U Leicester), G. Tagliaferri (INAF-OAB),
T. N. Ukwatta (GSFC/GWU), D. E. Vanden Berk (PSU) and
H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team:

At 19:53:02 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 080430 (trigger=310613).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 165.322, +51.689 which is 
   RA(J2000) = 11h 01m 17s
   Dec(J2000) = +51d 41' 22"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single FRED peak
structure with a duration of about 20 sec.  The peak count rate
was ~6000 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 19:53:50.9 UT, 48.9 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
165.31041, 51.68546 which is equivalent to:
   RA(J2000)  = 11h 01m 14.50s
   Dec(J2000) = +51d 41' 07.7"
with an uncertainty of 2.7 arcseconds (radius, 90% containment). This
location is 28 arcseconds from the BAT onboard position, within the BAT
error circle. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (9.59e+19
cm^-2, Kalberla et al. 2005), with an excess column of 3 (+1.33/-1.17)
x 10^21 cm^-2 (90% confidence). The relation of Grupe et al. (2007)
implies that this burst has a redshift z<3.5, although high redshift
fits to the absorbed XRT spectrum are possible if paired with an
anomalously large column. A summary of the promptly downlinked data is
given at http://www.swift.ac.uk/sper/310613/. 

The initial flux in the 2.5 s image was 1.26e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 400 seconds with the v filter starting
164 seconds after the BAT trigger. There is a candidate afterglow in the
rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	11:01:14.71 = 165.3113
  DEC(J2000) = +51:41:08.5  =  51.6857
with a 1-sigma error radius of about 0.5 arc sec. This position is 2.2 arc sec. 
from the center of the XRT error circle. The estimated magnitude is 17.6 with a
1-sigma error of about 0.5 mag. A white filter finding chart exposure was also
taken before the v filter, showing that the afterglow is fading.  No correction
has been made for the expected extinction of about 0.04 magnitudes. 

Burst Advocate for this burst is C. Guidorzi (cristiano.guidorzi AT brera.inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

M. Jelinek, P. Kubanek, J. Gorosabel, A. J. Castro-Tirado, F.
Aceituno (IAA-CSIC Granada), L. Sabau-Graziati (INTA Madrid),
A. de Ugarte Postigo (ESO Santiago), R. Hudec (ASU-CAS
Ondrejov), P. Perez-Gonzalez and J.  Zamorano (UCM Madrid)
report on behalf of a larger collaboration:

The BOOTES-1 0.3m telescope in South Spain observed GRB
080413A, starting at 19:53:36 UT (34 sec after the GRB). A
sequence of preprogrammed 6 sec, 20 and 60 sec exposures was
obtained. We find an optical counterpart at the coordinates
(J2000)

11:01:14.777  +51:41:08.61

with an unfiltered magnitude ~17.0 at ~60s after the GRB.

We continue observing the object with the 1.5m telescope at
Observatorio Sierra Nevada, which confirms the reality of the
object.


-- 
Martin Jelinek, +420602105255, +34617840945, sirrah.cz/mates
       Instituto de Astrofisica de Andalucia, Granada

# vim:set ai et sts=8 tw=60:

Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona),
David W. Hogg (NYU), Michael R. Blanton (NYU), David J. Schlegel
(LBNL), J. Brinkmann (APO), Donald Q. Lamb (Chicago), Donald
P. Schneider (PSU), and Daniel E. Vanden Berk (PSU) report:

The Sloan Digital Sky Survey (SDSS) imaged the field of burst
GRB080430 prior to the burst.  As these data should be useful
as a pre-burst comparison and for calibrating photometry,
we are supplying the images and photometry measurements for
this GRB field to the community.

Data from the SDSS, including 5 FITS images, 3 JPGS, and
3 files of photometry and astrometry, are being placed at
http://mizar.as.arizona.edu/~grb/public/GRB080430

We supply FITS images in each of the 5 SDSS bands of a 8'x8'
region centered on the GRB position (ra=165.322 (11:01:17.3),
dec=51.6890 (51:41:20.4); Swift-BAT TRIGGER 310613), as well
as 3 gri color-composite JPGs (with different stretches). The
units in the FITS images are nanomaggies per pixel.  A pixel
is 0.396 arcsec on a side. A nanomaggie is a flux-density unit
equal to 10^-9 of a magnitude 0 source or, to the extent that
SDSS is an AB system, 3.631e-6 Jy.  The FITS images have WCS
astrometric information.

In the file GRB080430_sdss.calstar.dat, we report photometry
and astrometry of 193 bright stars (r<20.5) within 15' of the
burst location.  The magnitudes presented in this file are asinh
magnitudes as are standard in the SDSS (Lupton 1999, AJ, 118,
1406). Beware that some of these stars are not well-detected
in the u-band; use the errors and object flags to monitor
data quality.

In the files GRB080430_sdss.objects_flux.dat and
GRB080430_sdss.objects_magnitudes.dat, we report photometry
of 582 objects detected within 6' of the GRB position.
We have removed saturated objects and objects with model
magnitudes fainter than 23.0 in the r-band.  The fluxes listed
in GRB080430_sdss.objects_flux.dat are in nanomaggies while
the magnitudes listed in GRB080430_sdss.objects_magnitudes.dat
are asinh magnitudes.

All quantities reported are standard SDSS photometry, meaning
that they are very close to AB zeropoints and magnitudes are
quoted in asinh magnitudes.  Photometric zeropoints are known
to about 2% rms.  None of the photometry is corrected for
dust extinction.  The Schlegel, Finkbeiner, and Davis (1998)
predictions for this region are A_U=0.061 mag, A_g=0.045 mag,
A_r = 0.032 mag, A_i=0.025 mag, and A_z=0.017 mag.

There are currently no objects within 6 arcminutes of the GRB
position in the SDSS spectroscopic database.


SDSS astrometry is generally better than 0.1 arcsecond per
coordinate.  Users requiring high precision astrometry should
take note that the SDSS astrometric system can differ from
other systems such as those used in other notices; we have
not checked the offsets in this region.

More detailed information pertaining to our SDSS GRB releases
can be found in our initial data release paper (Cool et
al. 2006, PASP 118, 733).  See the SDSS DR4 documentation for
more details: http://www.sdss.org/dr5.

These data have been reduced using a slightly different
pipeline than that used for SDSS public data releases.
We cannot guarantee that the values here will exactly match
those in the data release in which these data are included.
In particular, we expect the photometric calibrations to differ
by of order 0.01 mag.

This note may be cited, but please also cite the SDSS data
release paper, Adelman-McCarthy et al. (2007, ApJS, 172, 634),
when using the data or referring to the technical documentation.

A. de Ugarte Postigo, L. Christensen (ESO), J. Gorosabel (IAA-CSIC),
C. Th�ne (Dark), D.A. Kann (TLS), A. Mora (UAM), T. Szeifert (ESO),
M. Jelinek, A.J. Castro-Tirado (IAA-CSIC), S. Pedraz (CAHA),
N. Cardiel, D. Montes (UCM). On behalf of a larger collaboration report:

We have obtained spectroscopic observations of GRB 080430 from the 2.2m
Calar
Alto telescope (+CAFOS) starting at 21:11 UT (78 minutes after the
burst). The
observations consisted of 3x1200s integrations in low resolution. The
signal to noise
ratio is low but after a preliminary reduction we may conclude:

1) Continuum is clearly detected down to 3500 Angstroms, implying a
redshift smaller
than 1.9.
2) We detect an absorption feature at ~4900 Angstroms that we suggest to
be the
MgII doublet (2796.3, 2803.5), implying a most probable redshift of ~0.75.

Further analysis is ongoing. Additional spectroscopic observations are
encouraged.

This message may be cited.

M. Kocka, M. Nekola, J. Strobl, R. Hudec, C. Polasek (AsU CAS - Ondrejov),
M. Jelinek, P. Kubanek (IAA-CSIC - Granada),
R. Novak (N. Copernicus Observatory - Brno)
F. Munz (IASF/INAF - Bologna)

The 0.5m D50 telescope in AsU CAS Ondrejov, Czech Republic observed
GRB080430. Observation started at 20:57:02 UT. After 29 x 20 sec
exposures we detected optical counterpart at the coordinates:

(J2000) 11:01:14.7  +51:41:08.6  (M. Jelinek & al; GCN CIRCULAR 7648
Loading...
 
 )

Calibrated to near USNO et ESO star in R magnitude ~ 18.9mag (21:02:23 
UT mid-time of exposure)  
http://physics.muni.cz/~koci/GRB080430/grb080430.jpg

The 0.4m N. Copernicus Observatory telescope at Brno Czech Republic also 
observed
same coordinates with the same results.
http://ccder.blogspot.com/

Further analysis is in progress

This message may be cited.

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 18 s of overlapping XRT Photon Counting mode and UVOT
data for GRB 080430, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 165.31109, +51.68539 which is equivalent
to:

RA (J2000): 11h 01m 14.66s
Dec (J2000): +51d 41' 07.4"

with an uncertainty of 1.7 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest position
can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is
described by Goad et al. (2007, A&A, 476, 1401
http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an
extension of this method.

This circular was automatically generated, and is an official product of the
Swift-XRT team.

C. Guidorzi, J. Mao (INAF-OAB), P. Evans and K.L. Page (Leicester)
report on behalf of the Swift-XRT team:

The Swift-XRT began observing GRB 080430 (trigger=310613, Guidorzi et
al., GCN Circ. 7647
Loading...
 
 ) in Window Timing mode, 55 s after the BAT
trigger. Using 2 ks of overlapping XRT and UVOT data, we can improve
the UVOT-enhanced XRT position given by Evans in al. (GCN Circ. 7652
Loading...
 
 )
to RA, Dec = 165.31104, +51.68558 which is equivalent to:

RA (J2000): 11h 01m 14.65s
Dec (J2000): +51d 41' 08.1"

with an uncertainty of 1.4 arcsec (radius, 90% confidence).

The light curve of the first five orbits, from 55 s to 24.7 ks,
totalling 10.3 ks of exposure, can be modelled with a double broken
power law with the following best-fitting parameters:
alpha_1=2.34+/-0.16, t_break1=309 (-33,+58) s, alpha_2=0.38+/-0.06,
t_break2=10.3 (-2.2,+3.8) ks, alpha_3=0.65+/-0.17 (chisq/dof=77/81).

The WT mode spectrum spanning from 55 to 138 s can be fit by an absorbed
power-law model, with a photon index of 2.42 (-0.14, +0.27) and column
density of 4.6(-2.6, +3.2)e20 cm^-2, which is in excess of the average
Galactic column density in this direction of 9.6e19 cm^-2.
The PC mode spectrum of orbits 2 to 5, spanning from 5.6 to 24.7 ks,
is fit with a higher column density, (2.0+/-0.4)e21 cm^-2 and
a power-law index of 2.3+/-0.2.
The corresponding observed (unabsorbed) 0.3-10 keV flux is 5.0e-12
(8.5e-12) erg cm^-2 s^-1.

If the burst continues to decay at the same rate, we predict an
XRT count rate of 3.8e-2 count/s at T+24 hours, which corresponds
to an observed 0.3-10 keV flux of approximately 1.7e-12 erg cm^-2 s^-1.

This circular is an official product of the Swift-XRT team.

A. Cucchiara and D. B. Fox (Penn State) report:

"Starting on 2008 May 1.21 UT we used the Marcario LRS spectrograph
on the Hobby-Eberly Telescope (R ~ 230) to obtain a 1200s spectrum
of the optical afterglow of GRB 080430 (Guidorzi et al., GCN 7647
Loading...
 
 ).
The spectrum covers the wavelength range 4100 to 10,500 Angstrom.  We
clearly observe metal absorption features corresponding to the MgII
doublet (2796, 2803 A) and MgI (2852 A) at redshift z = 0.767. The
spectrum does not show any other significant features, consistent
with Calar Alto telescope observations (de Ugarte Postigo et al.,
GCN 7650
Loading...
 
 ).

We thank the HET staff for performing this observation."

M. Andreev, A. Sergeev (Terskol Branch of Institute of Astronomy), Ju.
Babina (CrAO), V. Petkov, A. Kurenya (BNO INR RAS), A. Pozanenko (IKI) on
behalf of larger GRB follow up collaboration  report:

We observed the afterglow (Klotz et al. GCN 7646
Loading...
 
 , Guidorzi et al. GCN 7647
Loading...
 
 ,
Jelinek et al. GCN 7648
Loading...
 
 ) of GRB080430 (Guidorzi et al. GCN 7647
Loading...
 
 ) with
Zeiss-600 of  Mt.Terskol observatory on Apr.30.  The fading afterglow is
clearly detected in combined images. A photometry of the OT against
USNO-B1.0 stars is following:

UT,              Exposure,   R_mag
(mid time)

Apr.30.8906  15 x 60s  19.10  +/- 0.20
Apr.30.9014  15 x 60s  19.40  +/- 0.20
Apr.30.9130  15 x 60s  19.75  +/- 0.25

The message may be cited.

M. Stamatikos (GSFC/ORAU), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
C. Guidorzi (INAF-OAB), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
K. McLean (GSFC/UMD), D. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
G. Sato (GSFC/ISAS), J. Tueller (GSFC), T. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 080430 (trigger #310613)
(Guidorzi, et al., GCN Circ. 7647
Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 165.331, 51.682 deg, which is 
   RA(J2000)  =  11h 01m 19.4s 
   Dec(J2000) = +51d 40' 55.5" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
 
The mask-weighted light curve shows a single FRED peak starting at ~T-0.7 sec,
peaking at ~T+1.5 sec, and ending at ~T+60 sec.  T90 (15-350 keV) is
16.2 +- 2.4 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.3 to T+21.3 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.73 +- 0.09.  The fluence in the 15-150 keV band is 1.2 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+1.70 sec in the 15-150 keV band
is 2.6 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/310613/BA/

Arto Oksanen (Muurame, Finland) and Veli-Pekka Hentunen (Varkaus, Finland) 
report to the AAVSO High Energy Network the following optical observations 
of GRB 080430 (Guidorzi et al., GCN Circular #7647
Loading...
 
 ):

Arto Oksanen (Hankasalmi Obs., Hankasalmi, Finland) reports the detection 
of the optical counterpart of GRB 080430.  Unfiltered observations were 
made using a 0.4-meter RC telescope with an SBIG STL-1001E CCD.  The 
initial Swift XRT position was observed unfiltered with an initial set of 
10 60-second exposures having a mid-point time of 2008 April 30, 20:08:54 
UT; the afterglow was detected with a magnitude of 18.1 +/- 0.05 
calibrated relative to GSC 3450-0639.  Astrometry of the initial frames 
yields a position of RA 11:01:14.76 , Dec +51:41:08.9 (USNOA2.0 ref, +/- 
0.4 arcseconds), which is within the stated uncertainties of the UVOT 
position (GCNCirc #7647).

Images taken between April 30.839 and April 30.969 UT were reanalyzed and 
calibrated relative to two USNO-B1.0 stars of magnitude ~16.5. Photometry 
of combined frames yields a smoothly decaying light curve during the span 
of observations:

    obs midpoint 	  CR	error
2008 April 30.839	17.798	0.088
2008 April 30.849	18.329	0.120
2008 April 30.860	18.484	0.087
2008 April 30.875	18.751	0.076
2008 April 30.893	18.868	0.055
2008 April 30.911	18.956	0.052
2008 April 30.929	19.044	0.067
2008 April 30.949	19.012	0.064
2008 April 30.969	19.156	0.076

A detailed report of the initial observations is available at the following URL:
ftp://ftp.aavso.org/grb/A.Oksanen_GRB080430_2454587.38588_.txt

A FITS image of this observation is available at the following URL:
ftp://ftp.aavso.org/grb/A.Oksanen_GRB080430_2454587.38588_.fits


Markku Nissinen and Veli-Pekka Hentunen (Taurus Hill Observatory, Varkaus, 
Finland) also report the detection of the optical afterglow of GRB 080430. 
Observations were made using a Meade LX-200 0.3-meter telescope with an 
SBIG ST8-XME CCD; observations were made using both clear and R filters. 
A total of six 600-second exposures were obtained having an average 
midpoint time of 2008 April 30.943.  Photometry of the combined clear and 
Rc frames yields magnitudes of CR=19.2+/-0.3 and R=19.5+/-0.5 calibrated 
relative to the GSC2.3 star N7JI005540.  The observers noted the sky was 
not completely dark due to their high latitude and time of year.

The AAVSO thanks the Curry Foundation for their continued support of the 
AAVSO International High Energy Network.

Christina C. Thoene (DARK), Johan P. U. Fynbo (DARK), Antonio de Ugarte
Postigo (ESO), D. Alexander Kann (TLS), Nicolaas E. Groeneboom, �ystein
Rudjord, Jostein R. Kristiansen (Univ. Oslo) and Tapio Purismo (NOT)
report:

We observed the afterglow (GCN 7646
Loading...
 
 , Klotz et al.) of GRB 080430 (GCN
7647
Loading...
 
 , Guidorzi et al.) with MOSCA at the NOT/La Palma on Apr. 30 starting
1.21h after the burst. Observations in UBVRI filters with exposure times
of 150s in each filter were acquired.
The afterglow is clearly detected in all bands and we derive the following
preliminary magnitudes based on the pre-burst SDSS calibrations (GCN 7649
Loading...
 
 ,
Cool et al.) and standard transformations between SDSS and Bessell
filters, times given are the start of the exposures.

t-t0(h)  band   mag
1.92     U         19.9 +- 0.2
1.74     B         19.8 +- 0.1
1.56     V         19.3 +- 0.1
1.21     R         19.0 +- 0.1
1.38     I           18.7 +- 0.1

The blue colors and the detection down to the U band are consistent with
the low redshift of that burst, z=0.767 as found by de Ugarte Postigo et
al. (GCN 7650
Loading...
 
 ) and Cucchiara et al. (GCN 7654
Loading...
 
 ).

Poonam Chandra (NRAO/UVA) and Dale A. Frail (NRAO) report on behalf
of the Caltech-NRAO-Carnegie GRB Collaboration:

"We used the Very Large Array to observe the field of view toward GRB
080430 (GCN 7647
Loading...
 
 ) at a frequency of 8.46 GHz at 2008 May 1.17 UT.
We do not detect the GRB afterglow at the UVOT afterglow position (GCN 7647
Loading...
 
 ).
The flux density at the  GRB afterglow position is 68 � 46 uJy.

The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."

W.B. Landsman (NASA/GSFC) and C. Guidorzi (INAF-OAB)  report on behalf 
of the Swift/UVOT team

The Swift/UVOT observed the field of GRB 080430 starting at 58s after  
the BAT trigger (Guidorzi et al., GCN 7647
Loading...
 
 ). We detect the afterglow in 
all seven UVOT filters at the position

RA(J2000.0)  =   11:01:14.66
DEC(J2000.0) =  +51:41:08.4

with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence).  
This position is consistent with the enhanced XRT position (Guidorzi et 
al. GCN 7653
Loading...
 
 )
and the position reported from  BOOTES obervations by Jelinek et al.  
(GCN 7648
Loading...
 
 ).     The detection in the UVW2 (1950 A) filter is consistent 
with the
redshift of ~0.76 determined from spectroscopic observations by Deugarte 
Postigo et al. (GCN 7650
Loading...
 
 ) and  Cucchiara & Fox (GCN 7654
Loading...
 
 ). The temporal 
slope in the white filter out to 30400 seconds is approximately alpha = 
0.23.

UVOT photometry from early individual images is reported below.     

Filter    Tmid(s)     Expo(s)            Magnitude
-----------------------------------------------------
White      108          98              17.08 � 0.03
White      928          98              18.23 � 0.05
v          364         393              17.64 � 0.06
v         1184         393              18.50 � 0.09
b         5989         197              20.05 � 0.21
u         5784         197              18.92 � 0.12
w1        7014         197              18.89 � 0.16
m2        6809         197              18.88 � 0.22
w2        5684         197              19.24 � 0.20
-----------------------------------------------------

These magnitudes are not corrected for the Galactic extinction  
corresponding to a reddening of E{B-V} = 0.012 mag (Schlegel et al. 
1998).  The photometry is on the UVOT flight system described in Poole 
et al. (2008,MNRAS,383,627).

I. Khamitov (TUG), I. Bikmaev, R. Gumerov,
A. Nemtinov, N. Sakhibullin (KSU/AST),
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)

report:

The optical counterpart (GCN7646
Loading...
 
 ) of GRB 080430 (GCN 7647
Loading...
 
 ) was observed 
with Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK 
National Observatory, Turkey), starting at May 01, 21:58 UT, i.e.
~26.08 hours after the burst, using Andor CCD.

A series of frames 3*300s in R and 3*600s in B bands were made.
The afterglow is clearly detected  in all images. Using USNO-B1 star
(416-022819, RA=11:01:16.86, DEC=+51:40:38.5, B2MAG=17.79, R2MAG=16.61)
we estimated the following magnitudes for the OT  on combined images:

t-t0 (h)	band	mag 	err
26.25		R	21.3	0.1
27.98		B	22.3	0.1


-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.

A. de Ugarte Postigo (ESO), C.C. Th�ne (Dark), F. Aceituno (IAA-CSIC),
Nicolaas E. Groeneboom, �ystein Rudjord, Jostein R. Kristiansen (Univ.
Oslo)
and Tapio Purismo (NOT) on behalf of a larger collaboration report:

We are continuing with the monitoring of the afterglow (Klotz et al. GCN
7646
Loading...
 
 )
of GRB 080430 (Guidorzi et al., GCN 7647
Loading...
 
 ) with the 1.5m OSN telescope
(Sierra
Nevada Observatory) and the 2.5m NOT+MOSCA (Roque de los Muchachos
Observatory) in I band. During the first day of observations we observe a
steady
decay with a shallow slope of alpha ~ 0.6 (f ~ t^-alpha), being at a
magnitude of
I ~ 20.5 one day after the burst.

Further observations are encouraged. This message can be cited.

S. B. Pandey, Rupak Roy and Brijesh Kumar (ARIES, NainiTal, India, on behal=
f of larger Indian GRB collaboration)
We observed Swift GRB 080430 with 1.04m telescope NainiTal starting ~20.0 h=
ours after the burst (Guidorzi et al. GCN 7647
Loading...
 
 ). Observations were performe=
d in R_c and I_c filters.
Photometry of one of the R_c frame (exposure time 1800s) shows theafterglow=
 around ~ 20.5 mag as reported in GCN 7646
Loading...
 
  and GCN 7648
Loading...
 
 . The reported magni=
tude is determined in comparison to nearby USNO stars.
This message may be cited.

C.Rinner ; F.Kugel report:

We imaged the field of GRB 080430 detected by SWIFT
with the TEL 0.5-m f/3 reflector
located at Observatoire Chante-Perdix - 04 Banon, France (A77 mpc station)

The observations started at 21:33:18 (UT).
24 exposures of 120s were carried out and weather conditions
were good.

We observe a new source in the error box given by SWIFT
at the following position:

RA(J2000.0) = 11h 01m 14.76s
DEC(J2000.0) +51d 41' 08.3"
+/-0.3"

magnitude = 18.6 +/-0.3

Astrometry and magnitudes were measured with the  USNO-SA2.0 catalogue.

No change magnitude was observed during the one hour observation.

More information and pictures here :
http://pagesperso-orange.fr/fkometes/pages/GRB080430.html

C.Rinner ; F.Kugel  report:

We are continuing with the monitoring of the afterglow (Klotz et al. GCN
7646
Loading...
 
 ) with the TEL 0.5-m f/3 reflector
located at Observatoire Chante-Perdix - 04 Banon, France (A77 mpc 
station, N43.9997 E5.6475)

The observations started at 20:39:12 (UT).
9 unfiltered exposures of 120s were carried out and weather conditions
were good.

We observe a weak reduction in magnitude

RA(J2000.0) = 11h 01m 14.76s
DEC(J2000.0) +51d 41' 08.3"
�0.3"

magnitude = 19.6 �0.3 one day after the burst.

Astrometry and magnitudes were measured with the  USNO-SA2.0 catalogue.

More information and picture here :

http://pagesperso-orange.fr/fkometes/pages/GRB080430.html

C.Rinner ; F.Kugel  report:

May 02

We are continuing with the monitoring of the afterglow (Klotz et al. GCN
7646
Loading...
 
 ) with the TEL 0.5-m f/3 reflector
located at Observatoire Chante-Perdix - 04 Banon, France (A77 mpc
station, N43.9997 E5.6475)

The observations started at 20:21:42 (UT).36 unfiltered exposures of 120s were 
carried out; although weak the source is still visible (SNR = 4.4) on an 
addition of 28 exposuress (cloudy passages on the other images). Measured 
magnitude = 20.6 two day after the burst.

Astrometry and magnitudes were measured with the  USNO-SA2.0 catalogue.

More information and picture here :

http://pagesperso-orange.fr/fkometes/pages/GRB080430.html

D. A. Kann, F. Ludwig, R. Filgas and S. Klose (TLS tautenburg) report:

We imaged the afterglow (Klotz et al., GCN 7646
Loading...
 
 ) of GRB 080430 (Guidorzi 
et al., GCN 7647
Loading...
 
 ) with the TLS Schmidt telescope one day after the GRB. 
Direct RRM observations a day earlier were unobtainable due to persistent 
bad weather. We obtained 22 180 second images starting with twilight under 
good conditions and at airmass 1. The afterglow is visible on all single 
images.

From the SDSS photometry of the field (Cool et al., GCN 7649
Loading...
 
 ), we find 
that the bright star southeast of the afterglow, at R.A. = 11:01:16.88, 
Dec. = +51:40:38.6 has g = 17.111, r = 16.539 and i = 16.377. Using the 
transformations of Jester et al. 2005, we find Rc = 16.458 for this star. 
Using it as a comparison star, we derive for the afterglow from a stack of 
all images:

time after burst	Rc	dRc

1.020536 days		21.20	0.06

This is in good agreement with the slightly later measurement of Khamitov 
et al. (GCN 7661
Loading...
 
 ) but significantly fainter than the magnitude reported by 
Pandey et al. (GCN 7663
Loading...
 
 ) for an observation a few hours earlier.

Data analysis was delayed by access problems.

This message may be cited.

J.Nicolas reports:

Visible Obervation afterglow radiation of the start gamma GRB080430
TEL 0.28-m F/6.5 reflector
Observatory:Vallauris 07:30:49 E 43:34:40 N B51

Composite of 26 images of 90s without filter
Photometry at magnitude 19
Date 08/04/30 22h15 UT

Using the USNO-A2 catalog, the source is located at:
RA (J200O)  = 11h 01m 14.76s
DEC (J2000) = +51d 41' 08.46"

The Image can be found at
http://astrosurf.com/jnicolas/sursaut_gamma.htm

M. Andreev, A. Sergeev (Terskol Branch of Institute of Astronomy), Ju. 
Babina (CrAO), V. Petkov, A. Kurenya (BNO INR RAS), A. Pozanenko (IKI) on 
behalf of larger GRB follow up collaboration  report:

We observed the afterglow (Klotz et al. GCN 7646
Loading...
 
 , Guidorzi et al. GCN 7647
Loading...
 
 , 
Jelinek et al. GCN 7648
Loading...
 
 ) of GRB080430 (Guidorzi et al. GCN 7647
Loading...
 
 ) with 
Zeiss-600 of  Mt.Terskol observatory on May. 01.  The  afterglow is detected 
in a combined image. A photometry of the OT against USNO-B1.0 stars is 
following:

UT,              Exposure,   R_mag
(mid time)

May.01.8795 15x90s  20.9  +/-0.3

The message may be cited.

F. Terra (Second University of Roma "Tor Vergata"),  F. Munz (INAF/IASF
     Bologna) G. Greco, C. Bartolini, A. Guarnieri,A. Piccioni (Bologna
     University), D. Nanni (INAF/OAR and Second University of Rome "Tor
     Vergata"), G. Pizzichini(INAF/IASF Bologna), S. Galleti and S. Bernabei
     (Bologna Observatory) report:

    During the night between 08/04/30 and 08/05/01 we observed the OT of
    GRB080430 (Guidorzi et al., GCN 7647
Loading...
 
 , Klotz, Boer & Atteia, GCN 7646
Loading...
 
 )
    with the 1.52  cm telescope of the Bologna Observatory in Loiano in good
    weather conditons, airmass  between 1 and 1.6, seeing less than 4".
    We obtained a total of 14 frames in Rc, V, B and I.
    Rc magnitudes went from 19.47 +- 0.11 at 2454587.40325 UT to 20.53 +- 0.10
    at 2454587.54819 UT.
    Rc calibration was obtained from the NOMAD catalog.

     Our  images have been posted in our public directory
     from where they can be retrieved by sftp using
     hostname: ermione.bo.astro.it
     username: publicGRB
     password: GRB_bo
     directory: /home/publicGRB/GRB080430/

F. Terra (Second University of Roma "Tor Vergata"),  F. Munz (INAF/IASF
    Bologna) G. Greco, C. Bartolini, A. Guarnieri,A. Piccioni (Bologna
    University), D. Nanni (INAF/OAR and Second University of Rome "Tor
    Vergata"), G. Pizzichini(INAF/IASF Bologna),  S. Galetti and S. Bernabei
    (Bologna Observatory) report:

    During the night between 08/04/30 and 080501 we observed the OT of
    GRB080430 (Guidorzi et al., GCN 7647
Loading...
 
 , Klotz, Boer & Atteia, GCN 7646
Loading...
 
 )
    in Rc, V, B AND I  with the 1.52  cm telescope of the Bologna Observatory
    in Loiano in good weather conditons, airmass  between 1 and 1.6,
    seeing less than 4".
    Calibration was obtained from the NOMAD catalog in the Rc filter and from
    the SDSS observations by Cool et al. in GCN 7649
Loading...
 
  for the other filters.
    We obtain the following magnitudes
    obs midpoint      duration filter mag   error
                       seconds
    2454587.40325        600     Rc  19,47  0,11
    2454587.41120        600     V   19,20  0.12
    2454587.42067        600     Rc  19,75  0,11
    2454587.43274       1200     B   19,54  0,12
    2454587.44788        600     Rc  19,60  0,15
    2454587.45720        600     I   19,03  0,05
    2454587.46673        600     Rc  19,75  0,11
    2454587.47927        600     V   19,44  0,12
    2454587.48806        600     Rc  19,96  0,10
    2454587.51098        600     Rc  20,28  0,09
    2454587.52303        600     Rc  20,01  0,09
    2454587.53175        600     Rc  20,27  0,15
    2454587.53946        600     I   19,14  0,06
    2454587.54819        600     Rc  20,53  0,10

    Our  images have been posted in our public directory
    from where they can be retrieved by sftp using
    hostname: ermione.bo.astro.it
    username: publicGRB
    password: GRB_bo
    directory: /home/publicGRB/GRB080430/