Gamma-ray Burst 070520

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 20 May 07 13:06:49 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     279817,   Seg_Num: 0
GRB_RA:          193.316d {+12h 53m 16s} (J2000),
                 193.375d {+12h 53m 30s} (current),
                 192.913d {+12h 51m 39s} (1950)
GRB_DEC:         +74.993d {+74d 59' 36"} (J2000),
                 +74.953d {+74d 57' 12"} (current),
                 +75.264d {+75d 15' 52"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=1842 [image_cnts]
TRIGGER_DUR:     88.000 [sec] 
TRIGGER_INDEX:   20000     E_range: 15-50 keV
BKG_INTEN:       0 [cnts]
BKG_TIME:        0.00 SOD {00:00:00.00} UT
BKG_DUR:         0 [sec]
GRB_DATE:        14240 TJD;   140 DOY;   07/05/20
GRB_TIME:        47110.03 SOD {13:05:10.03} UT
GRB_PHI:         -139.07 [deg]
GRB_THETA:        30.01 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    7.99 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  -2  +0  +0 -15  +1 
SUN_POSTN:        56.94d {+03h 47m 45s}  +19.97d {+19d 58' 02"}
SUN_DIST:         81.20 [deg]   Sun_angle= -9.1 [hr] (East of Sun)
MOON_POSTN:      111.86d {+07h 27m 27s}  +26.03d {+26d 02' 01"}
MOON_DIST:        62.72 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      122.77, 42.13 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      127.41, 65.49 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 133.07,-6.03 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 20 May 07 13:08:36 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     279817,   Seg_Num: 0
GRB_RA:          254.1979d {+16h 56m 47.4s} (J2000),
                 254.2354d {+16h 56m 56.4s} (current),
                 253.9445d {+16h 55m 46.6s} (1950)
GRB_DEC:         +55.2974d {+55d 17' 50.6"} (J2000),
                 +55.2862d {+55d 17' 10.3"} (current),
                 +55.3738d {+55d 22' 25.7"} (1950)
GRB_ERROR:       5.4 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       30 [cnts]
IMG_START_DATE:  14240 TJD;   140 DOY;   07/05/20
IMG_START_TIME:  47268.72 SOD {13:07:48.72} UT,   158.7 [sec] since BAT Trigger Time
CENTROID_X:      295.12,  raw= 295  [pixels]
CENTROID_Y:      327.58,  raw= 328  [pixels]
ROLL:            18.65 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -35.74
GRB_POS_XRT_Z:   69.85
IMAGE_URL:       sw00279817000msxps_rw.img
SUN_POSTN:        56.94d {+03h 47m 45s}  +19.97d {+19d 58' 03"}
SUN_DIST:        103.32 [deg]   Sun_angle= 10.8 [hr] (West of Sun)
MOON_POSTN:      111.88d {+07h 27m 31s}  +26.03d {+26d 01' 49"}
MOON_DIST:        92.55 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:       83.49, 38.16 [deg] galactic lon,lat of the burst
ECL_COORDS:      228.56, 76.45 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 20 May 07 13:08:35 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     279817,   Seg_Num: 0
GRB_RA:          193.3636d {+12h 53m 27.2s} (J2000),
                 193.4227d {+12h 53m 41.4s} (current),
                 192.9618d {+12h 51m 50.8s} (1950)
GRB_DEC:         +74.9909d {+74d 59' 27.2"} (J2000),
                 +74.9509d {+74d 57' 03.3"} (current),
                 +75.2620d {+75d 15' 43.1"} (1950)
GRB_ERROR:       5.4 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.12e-09 [erg/cm2/sec]
GRB_SIGNIF:      7.68 [sigma]
IMG_START_DATE:  14240 TJD;   140 DOY;   07/05/20
IMG_START_TIME:  47268.72 SOD {13:07:48.72} UT,   158.7 [sec] since BAT Trigger Time
TAM[0-3]:        327.67 237.19 261.43 243.47
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:        56.94d {+03h 47m 45s}  +19.97d {+19d 58' 03"}
SUN_DIST:         81.21 [deg]   Sun_angle= -9.1 [hr] (East of Sun)
MOON_POSTN:      111.88d {+07h 27m 31s}  +26.03d {+26d 01' 49"}
MOON_DIST:        62.73 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      122.76, 42.14 [deg] galactic lon,lat of the burst
ECL_COORDS:      127.42, 65.50 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 20 May 07 13:09:47 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     279817,   Seg_Num: 0
POINT_RA:        193.283d {+12h 53m 08s} (J2000)
POINT_DEC:       +74.999d {+74d 59' 56"} (J2000)
POINT_ROLL:      318.945d
IMG_START_DATE:  14240 TJD;   140 DOY;   07/05/20
IMG_START_TIME:  47277.77 SOD {13:07:57.77} UT,   167.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        0.800
N_STARS:         28
X_OFFSET:        424 [pixels]
Y_OFFSET:        584 [pixels]
X_MAX:           1383 [pixels]
Y_MAX:           1543 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw00279817000msufc0167.fits
SUN_POSTN:        56.94d {+03h 47m 45s}  +19.97d {+19d 58' 03"}
SUN_DIST:         81.19 [deg]   Sun_angle= -9.1 [hr] (East of Sun)
MOON_POSTN:      111.89d {+07h 27m 34s}  +26.03d {+26d 01' 41"}
MOON_DIST:        62.71 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      122.78, 42.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      127.39, 65.49 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 20 May 07 13:10:14 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     279817,   Seg_Num: 0
POINT_RA:        193.283d {+12h 53m 08s} (J2000)
POINT_DEC:       +74.999d {+74d 59' 56"} (J2000)
POINT_ROLL:      318.945d
IMG_START_DATE:  14240 TJD;   140 DOY;   07/05/20
IMG_START_TIME:  47277.77 SOD {13:07:57.77} UT,   167.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        0.800
N_STARS:         28
X_OFFSET:        424 [pixels]
Y_OFFSET:        584 [pixels]
X_MAX:           1383 [pixels]
Y_MAX:           1543 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw00279817000msufc0167.fits
SUN_POSTN:        56.94d {+03h 47m 45s}  +19.97d {+19d 58' 03"}
SUN_DIST:         81.19 [deg]   Sun_angle= -9.1 [hr] (East of Sun)
MOON_POSTN:      111.90d {+07h 27m 35s}  +26.03d {+26d 01' 38"}
MOON_DIST:        62.71 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      122.78, 42.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      127.39, 65.49 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 20 May 07 13:10:55 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     279817,   Seg_Num: 0
POINT_RA:        193.283d {+12h 53m 08s} (J2000)
POINT_DEC:       +74.999d {+74d 59' 56"} (J2000)
ROLL:            318.945d
IMG_START_DATE:  14240 TJD;   140 DOY;   07/05/20
IMG_START_TIME:  47277.77 SOD {13:07:57.77} UT,   167.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     201359279
X_OFFSET:        715 [pixels]
Y_OFFSET:        986 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       875
Y_GRB_POS:       1146
BINNING_INDEX:   1
IM_URL:          sw00279817000msuni0167.fits
SUN_POSTN:        56.94d {+03h 47m 45s}  +19.97d {+19d 58' 04"}
SUN_DIST:         81.19 [deg]   Sun_angle= -9.1 [hr] (East of Sun)
MOON_POSTN:      111.90d {+07h 27m 37s}  +26.03d {+26d 01' 33"}
MOON_DIST:        62.71 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      122.78, 42.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      127.39, 65.49 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 20 May 07 13:11:01 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     279817,   Seg_Num: 0
GRB_RA:          193.316d {+12h 53m 16s} (J2000),
                 193.375d {+12h 53m 30s} (current),
                 192.913d {+12h 51m 39s} (1950)
GRB_DEC:         +74.993d {+74d 59' 36"} (J2000),
                 +74.953d {+74d 57' 12"} (current),
                 +75.264d {+75d 15' 52"} (1950)
GRB_DATE:        14240 TJD;   140 DOY;   07/05/20
GRB_TIME:        47110.03 SOD {13:05:10.03} UT
TRIGGER_INDEX:   20000
GRB_PHI:         -139.07 [deg]
GRB_THETA:        30.01 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     88.000 [sec] 
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    7.99 [sigma]
LC_URL:          sw00279817000msb.lc
SUN_POSTN:        56.94d {+03h 47m 45s}  +19.97d {+19d 58' 04"}
SUN_DIST:         81.20 [deg]   Sun_angle= -9.1 [hr] (East of Sun)
MOON_POSTN:      111.91d {+07h 27m 37s}  +26.03d {+26d 01' 33"}
MOON_DIST:        62.72 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      122.77, 42.13 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      127.41, 65.49 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Lightcurve.  
COMMENTS:           
COMMENTS:        The next comments were copied from the BAT_POS Notice:  
COMMENTS:        This is an image trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 133.07,-6.03 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 20 May 07 13:11:21 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     279817,   Seg_Num: 0
POINT_RA:        193.283d {+12h 53m 08s} (J2000)
POINT_DEC:       +74.999d {+74d 59' 56"} (J2000)
ROLL:            318.945d
IMG_START_DATE:  14240 TJD;   140 DOY;   07/05/20
IMG_START_TIME:  47277.77 SOD {13:07:57.77} UT,   167.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     201359279
X_OFFSET:        715 [pixels]
Y_OFFSET:        986 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       875
Y_GRB_POS:       1146
BINNING_INDEX:   1
IM_URL:          sw00279817000msuni0167.fits
SUN_POSTN:        56.94d {+03h 47m 45s}  +19.97d {+19d 58' 04"}
SUN_DIST:         81.19 [deg]   Sun_angle= -9.1 [hr] (East of Sun)
MOON_POSTN:      111.91d {+07h 27m 38s}  +26.03d {+26d 01' 30"}
MOON_DIST:        62.71 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      122.78, 42.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      127.39, 65.49 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN Circular #6423
P. Romano (Univ. Bicocca & INAF-OAB), S. D. Barthelmy (GSFC), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), C. Gronwall (PSU), C. Guidorzi (Univ Bicocca&INAF-OAB), V. Mangano (INAF-IASFPA), F. E. Marshall (NASA/GSFC), C. Pagani (PSU), D. M. Palmer (LANL), M. Stamatikos (NASA/ORAU), R. L. C. Starling (U Leicester) and S. D. Vergani (DIAS-DCU) report on behalf of the Swift Team:
At 13:05:10 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 070520 (trigger=279817). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 193.316, +74.993 which is
```
   RA(J2000)  =  12h 53m 16s
   Dec(J2000) = +74d 59' 36"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). This is an 88-sec image trigger, and as such the TDRSS lightcurve does not show anything significant above background, as is typical for image triggers.
The XRT began observing the field at 13:07:48 UT, 159 seconds after the BAT trigger. XRT found a X-ray source located at RA, Dec 193.3636, +74.9909 which is
```
   RA(J2000)  =  12h 53m 27.2s
   Dec(J2000) =  74d 59' 27.2"
```
with an uncertainty of 5.4 arcseconds (radius, 90% containment). This location is 45 arcseconds from the BAT on-board position, within the BAT error circle. The initial flux in the 2.5s image was 1.1e-09 erg/cm2/s (0.2-10 keV).
UVOT took a finding chart exposure of 77 seconds with the White (160-650 nm) filter starting 168 seconds after the BAT trigger. No afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The 3-sigma upper limit is 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02.
GCN Circular #6424
L.P. Xin, M.Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng, Y. Urata, and W.K. Zheng on behalf of EAFON report:
We have imaged the field of GRB 070520 (P. Romano et al., GCN 6423) with the EST 1m telescope at Xinglong Observatory? Observation started from 13:14:54 UT, 579s after the burst with R band filter, we derieved 3 sigam limit is ~20.6 in our 20*60s co-added images withmean time ~20minutes.
This message may be cited.
GCN Circular #6427
P. Romano (Univ Bicocca&INAF-OAB), A. Moretti (INAF-OAB), C. Guidorzi (Univ Bicocca&INAF-OAB), S.D. Vergani (DIAS-DCU) report on behalf of the Swift team:
We have analysed the first four orbits of XRT data on GRB 070520A (Romano et al., GCN Circ. 6423) with total observing times of 79 s in Windowed Timing mode (from T+165 to T+244 s) and 6.5 ks in Photon Counting mode (from T+3565 s). The Photon Counting mode image provides a refined XRT position at RA,DEC(J2000) = 193.36131,+74.99038 which is
```
RA(J2000)  = 12h 53m 26.72s
Dec(J2000) = +74d 59' 25.4"
```
with an uncertainty of 4.1 arcsec (radius, 90% containment). This is 2.6 arcsec from the initial X-ray position, and 43 arcsec from the initial BAT position (Romano et al., GCN Circ. 6423).
The XRT light curve exhibits an initial flaring behaviour throughout the first orbit (in the WT data, i.e., up to T+244 s) with an underlying power-law with slope 4.4+/-0.5. The PC data start at T+3565 s, when the count rate had decreased by three orders of magnitude. The PC data power-law slope is 0.1+/-0.4.
The mean WT spectrum, extracted during the flaring activity, can be fit with an absorbed power law with a photon index of 3.1+/-0.2 and a column density of (2.2+/-0.4)E21 cm^-2 significantly in excess of the Galactic value (2.3E20 cm^-2; Dickey & Lockman, 1990).
Assuming the source continues to decay at the present rate, we predict an XRT count rate of 1E-4 counts/s at T+24 hours, which corresponds to an unabsorbed flux of 5E-15 ergs cm^-2 s^-1.
This circular is an official product of the Swift XRT team.
GCN Circular #6428
C. Markwardt (GSFC/UMD), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), D. Palmer (LANL), A. Parsons (GSFC), P. Romano (Univ. Bicocca & INAF-OAB), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC) on behalf of the Swift-BAT team:
Using the data set from T-239 to T+963 sec from recent telemetry downlinks, we report further analysis of BAT GRB 070520A (trigger #279817) (Romano, et al., GCN Circ. 6423). The BAT ground-calculated position is RA, Dec = 193.255, 75.005 deg which is
```
   RA(J2000)  = 12h 53m  1.1s 
   Dec(J2000) = 75d  0' 16.6" 
```
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 67%.
The mask-weighted light curve shows single peak with a long tail. The peak starts at ~T+10 sec, peaks at T+35 sec, and ends at ~T+105 sec. The long tail appears to extend out to T+370+/-30 sec at the 0.02 +/- 0.01 ph/cm2/sec level. T90 (15-350 keV) is 18 +- 3 sec (estimated error including systematics).
The time-averaged spectrum from T+25.5 to T+45.4 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.60 +- 0.33. The fluence in the 15-150 keV band is 2.5 +- 0.5 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+35.80 sec in the 15-150 keV band is 0.4 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
GCN Circular #6430
T. Ishimura, T. Shimokawabe, N. Vasquez, Y. Yatsu, Y. Kudou and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:
We observed the field of GRB070520A (Romano et al., GCN 6423) with the 3-color 50cm MITSuME Telescope at Akeno, Japan starting at 13:15:15 UT, 10 min after the trigger, under a clear, but windy condition. In the co-added images of Ic, Rc, and g' bands, we did not detect any new source in the XRT error circle. The 3-sigma limiting magnitudes based on USNO-B1.0 (I-band) and NOMAD (R-band,g'-band) stars are following.
```
Filter   start time   end time    Exp(s)   Mag (3-sigma UL)  
-----------------------------------------------------------
Ic       13:15:15    15:06:06     60s * 91         20.3    
Rc       13:15:15    15:06:06     60s * 91         21.2    
g'       13:15:15    15:06:06     60s * 91         21.1    
-----------------------------------------------------------
```
GCN Circular #6439
S. Immler (USRA/GSFC) and P. Romano (Univ. Bicocca & INAF-OAB) report on behalf of the Swift/UVOT team:
The Swift/UVOT observed the field of GRB 070525A starting 152 s after the BAT trigger (Romano et al., GCN 6423). We do not find any source in any of the UVOT observations inside the XRT error circle. The 3-sigma upper limits for detecting a source inside the XRT error circle in the co-added frames are:
```
Filter            T_start(s)   T_stop(s)     Exp(s)     Mag (3-sigma UL)

White             168          4793          345        >20.2
V                 152          11162         1288       >19.6
B                 4389         6021          393        >20.0
U                 4184         16822         1142       >20.3
UVW1              3979         16047         1279       >20.1
UWM2              3774         11805         1021       >20.4
UVW2              4799         10249         1082       >20.5
```
The values quoted above are not corrected for the expected Galactic extinction corresponding to a reddening of E(B-V) = 0.02 mag towards the direction of the burst (Schlegel et al. 1998).
GCN Circular #6441
T. Hattori, K. Aoki (Subaru Telescope, NAOJ), and N. Kawai (Tokyo Tech) report on behalf of the Subaru GRB team:
"We observed the field of GRB 070520A (Romano et al., GCN 6423) with FOCAS on the Subaru Telescope in the z'-band from 06:32(UT) to 07:27(UT) May 21 with a total exposure of 1920 sec (120s*16) under a non-photometric condition with occasional clouds.
In the XRT error circle (Romano et al., GCN 6427), we find a possible afterglow candidate as a low-significance source (1.5 sigma) at
RA=12:53:26.52, Dec=74:59:26.6
with a positional uncertainty of 0.4", and a rough estimation of the magnitude z' ~ 24.
The image may be viewed at http://www.hp.phys.titech.ac.jp/nkawai/grb/070520A/
GCN Report 58.1
GCN_Report 58.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_58_1.pdf by P. Romano at U.Bicocca/INAF-OAB titled: "Swift observations of GRB 070520A"
GCN Circular #6446
A. C. Updike, J. R. Puls, and D. H. Hartmann (Clemson University) report on behalf of the Clemson GRB Follow-Up Team:
We used the 0.9m SARA telescope at Kitt Peak under decent weather conditions to image the field of GRB 070520A (GCN 6423, Romano et al.), beginning 17 hours after the burst. In 40 minutes of stacked exposures, we do not detect the object noted by Hattori et al. (GCN 6441) down to a limiting magnitude of 20 +/- 0.4 in the R-band. This magnitude is based on calibration to 9 USNO B1.0 stars.
The SARA Homepage can be found at: http://saraobservatory.org
This message may be cited.
GCN Circular #6484
V. Rumyantsev, D. Shakhovskoy (CrAO), V. Biryukov (CrAO, SAI MSU), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report:
We observed error box of GRB070520 (Romano et al., GCN 6423) with AZT-11 (1.25m) and 1-m Zeiss (Simeiz) telescopes of CrAO in R-band on May 20 bet= ween (UT)19:50 and 22:00. No object is found in a refined XRT error box (Romano et al., GCN 6427). Limiting magnitude of combined images is based on USNO A2.0:
```
Mid time (UT),  Exposure,   R_Lim (3sigma), Telescope,  Seeing
May 20.896       6x300       21.6             AZT-11     3.6"
May 20.835      53x60        22.4             1-m Zeiss  1.5"
```
The combined image of 1-m Zeiss telescope can be found in http://grb.rssi.ru/GRB070520/GRB050720_z1000_Simeiz.gif
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GCN Report 58.2
GCN_Report 58.2 has been posted: http://gcn.gsfc.nasa.gov/reports/report_58_2.pdf by P. Romano at U.Bicocca/INAF-OAB titled: "Final Swift observations of GRB 070520A"

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Jochen Greiner, last update: 12-Jun-2007 [Disclaimer]