Gamma-ray Burst 080120

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Sun 20 Jan 08 17:29:00 UT
NOTICE_TYPE:    INTEGRAL Wakeup
TRIGGER_NUM:    4821,   Sub_Num: 0
GRB_RA:         225.2864d {+15h 01m 09s} (J2000),
                225.3957d {+15h 01m 35s} (current),
                224.6083d {+14h 58m 26s} (1950)
GRB_DEC:        -10.8977d {-10d 53' 51"} (J2000),
                -10.9292d {-10d 55' 44"} (current),
                -10.7006d {-10d 42' 01"} (1950)
GRB_ERROR:      3.10 [arcmin, radius, statistical only]
GRB_INTEN:      9.46 [sigma]
GRB_TIME:       62914.73 SOD {17:28:34.73} UT
GRB_DATE:       14485 TJD;    20 DOY;   08/01/20
SC_RA:          232.88 [deg] (J2000)
SC_DEC:          -6.75 [deg] (J2000)
SUN_POSTN:      302.21d {+20h 08m 50s}  -20.14d {-20d 08' 36"}
SUN_DIST:        74.00 [deg]   Sun_angle= 5.1 [hr] (West of Sun)
MOON_POSTN:      96.51d {+06h 26m 01s}  +27.35d {+27d 21' 08"}
MOON_DIST:      129.39 [deg]
GAL_COORDS:     346.88, 40.65 [deg] galactic lon,lat of the burst
ECL_COORDS:     226.00,  5.98 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Possibly real GRB event

red DSS finding chart ps-file

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Sun 20 Jan 08 17:29:04 UT
NOTICE_TYPE:    INTEGRAL Refined
TRIGGER_NUM:    4821,   Sub_Num: 1
GRB_RA:         225.2490d {+15h 00m 60s} (J2000),
                225.3583d {+15h 01m 26s} (current),
                224.5711d {+14h 58m 17s} (1950)
GRB_DEC:        -10.8777d {-10d 52' 39"} (J2000),
                -10.9092d {-10d 54' 32"} (current),
                -10.6805d {-10d 40' 49"} (1950)
GRB_ERROR:      2.60 [arcmin, radius, statistical only]
GRB_INTEN:      23.06 [sigma]
GRB_TIME:       62917.73 SOD {17:28:37.73} UT
GRB_DATE:       14485 TJD;    20 DOY;   08/01/20
SC_RA:          232.88 [deg] (J2000)
SC_DEC:          -6.75 [deg] (J2000)
SUN_POSTN:      302.21d {+20h 08m 50s}  -20.14d {-20d 08' 36"}
SUN_DIST:        74.04 [deg]   Sun_angle= 5.1 [hr] (West of Sun)
MOON_POSTN:      96.51d {+06h 26m 01s}  +27.35d {+27d 21' 08"}
MOON_DIST:      129.35 [deg]
GAL_COORDS:     346.86, 40.69 [deg] galactic lon,lat of the burst
ECL_COORDS:     225.96,  5.99 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Possibly real GRB event

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Sun 20 Jan 08 17:32:00 UT
NOTICE_TYPE:    INTEGRAL Refined
TRIGGER_NUM:    4821,   Sub_Num: 2
GRB_RA:         225.2561d {+15h 01m 01s} (J2000),
                225.3654d {+15h 01m 28s} (current),
                224.5781d {+14h 58m 19s} (1950)
GRB_DEC:        -10.8836d {-10d 53' 00"} (J2000),
                -10.9151d {-10d 54' 53"} (current),
                -10.6864d {-10d 41' 10"} (1950)
GRB_ERROR:      2.57 [arcmin, radius, statistical only]
GRB_INTEN:      27.24 [sigma]
GRB_TIME:       62921.73 SOD {17:28:41.73} UT
GRB_DATE:       14485 TJD;    20 DOY;   08/01/20
SC_RA:          232.88 [deg] (J2000)
SC_DEC:          -6.75 [deg] (J2000)
SUN_POSTN:      302.21d {+20h 08m 51s}  -20.14d {-20d 08' 34"}
SUN_DIST:        74.04 [deg]   Sun_angle= 5.1 [hr] (West of Sun)
MOON_POSTN:      96.54d {+06h 26m 09s}  +27.35d {+27d 20' 57"}
MOON_DIST:      129.33 [deg]
GAL_COORDS:     346.86, 40.68 [deg] galactic lon,lat of the burst
ECL_COORDS:     225.97,  5.98 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Possibly real GRB event

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Sun 20 Jan 08 18:35:41 UT
NOTICE_TYPE:    INTEGRAL Offline
TRIGGER_NUM:    4821,   Sub_Num: 3
GRB_RA:         225.2547d {+15h 01m 01s} (J2000),
                225.3640d {+15h 01m 27s} (current),
                224.5767d {+14h 58m 18s} (1950)
GRB_DEC:        -10.8854d {-10d 53' 06"} (J2000),
                -10.9169d {-10d 55' 00"} (current),
                -10.6882d {-10d 41' 17"} (1950)
GRB_ERROR:      2.00 [arcmin, radius, statistical only]
GRB_INTEN:      27.24 [sigma]
GRB_TIME:       62921.73 SOD {17:28:41.73} UT
GRB_DATE:       14485 TJD;    20 DOY;   08/01/20
SC_RA:          232.88 [deg] (J2000)
SC_DEC:          -6.75 [deg] (J2000)
SUN_POSTN:      302.26d {+20h 09m 02s}  -20.13d {-20d 08' 00"}
SUN_DIST:        74.08 [deg]   Sun_angle= 5.1 [hr] (West of Sun)
MOON_POSTN:      97.25d {+06h 29m 00s}  +27.28d {+27d 16' 56"}
MOON_DIST:      128.71 [deg]
GAL_COORDS:     346.86, 40.68 [deg] galactic lon,lat of the burst
ECL_COORDS:     225.97,  5.98 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       refined_coordinates_after_offline_analysis

GCN Circular #7194
S.Mereghetti, A.Paizis (IASF-Milano), D.Gotz (CEA-Saclay), A.Manousakis, V.Beckmann, M. Beck (ISDC, Versoix), and J. Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report:
A GRB lasting about 20 s has been detected by IBAS in IBIS/ISGRI data at 17:28:30 UT of January 20. The coordinates (J2000) are:
```
RA = 225.2547
Dec= -10.8854
```
with an uncertainty of 2 arcmin (90% c.l.).
A preliminary analysis gives a peak flux in the 20-200 keV range of about 3 ph/cmq/s (1-s integration time) and a fluence over the same energy range of 1.5e-6 erg/cmq.
A plot of the light curve will be posted at
http://ibas.iasf-milano.inaf.it/IBAS_Results.html
This message can be cited.
GCN Circular #7195
B. Sbarufatti and V. Mangano (INAF-IASF PA) on behalf of the Swift XRT team
Swift XRT started a ToO observation of the INTEGRAL burst GRB080120 at 19:47 UT. The analysis of the initial 1.5 ks of data of the first orbit shows a single bright uncatologued X-ray source in the field at
```
  RA (J2000):  15h 01m 03.13s
 Dec (J2000): -10d 52' 31.8"
```
with an uncertainty of 3.8 arcsec (radius, 90% confidence). This is 46 arcsec away from the GRB position given in Mereghetti et al., GCN Circ. 7194. The source has a count rate of (2.1+-0.1)E-1 counts/s and, assuming a Crab spectrum, a flux of 1E-10 erg/cm2/s. More data are being collected that will be used to determine whether the source is fading and to perform a spectral analysis.
This Circular is an official product of the Swift XRT Team.
GCN Circular #7196
Norbert Schartel (ESA) reports:
XMM-Newton will observe GRB 080120 at location (RA=15h 01m 1.13s, DEC=-10 d 53' 7.4", J2000), starting at 23:00:00 UT, on Jan 20, 2008, for an exposure of about 20000 seconds.
GCN Circular #7197
T. Kruehler, J. Greiner, S. McBreen, S. Loew, A. Kuepcue-Yoldas, A. Yoldas (all MPE Garching) report for the GROND team:
We started observing GRB 080120 observed by INTEGRAL (Mereghetti et al. 2008, GCN #7194) simultaneously in grizJHK with GROND, mounted at the 2.2m MPI/ESO telescope at La Silla (Chile), at 7:02 UT, about 13.5 hrs after the GRB. At this time, the GRB location was becoming visible at 20 degrees above horizon.
We find an optical/NIR source inside the 3.8 arcsec Swift/XRT error circle of the X-ray afterglow (Sbarufatti et al. 2008, GCN #7195). The object is seen in all bands except K, implying a redshift smaller than 3.5.
The coordinates are (+-1 arcsec):
```
RA (2000.0) = 15h 01m 03.2s
Decl (2000.0) = -10d 52' 30"
```
We estimate rough magnitudes of g'=21.1, r'=20.5, i'=20.0, z'=19.8, J=19.6, H=19.4, K>18.9, calibrated against USNO and 2MASS stars. Given the high airmass and humidity, these estimates may have large errors.
No statement about variability can be made at this point. Observations are continuing.
GCN Circular #7198
P. Schady (MSSL-UCL) and B. Sbarufatti (INAF-IASF PA) report on behalf of the Swift UVOT team:
Swift UVOT started a ToO observation of the INTEGRAL burst GRB080120 at 2008-01-20T19:50 UT, ~2.4hrs after the INTEGRAL trigger (Mereghetti et al., GCN 7194). Observations were taken in the white and v-band only. A new source is detected within the XRT error circle (Sbarufatti & Mangano, GCN7195), in co-added images in both these filters at
```
RA: 15:01:03.276
DEC: -10:52:29.79
```
with an uncertainty of 0.6 arcsec (90% confidence). This is consistent with the position reported by Kruehler et al. (GCN 7197). The source is seen to decay in the white band and has the following magnitudes and 3-sigma upper limits (in the UVOT photometric system,Breeveld et al., GCN Circ. 6614)
```
Filter    Tstart   Exp      Magnitude
            (s)     (s)
white     9257     401      21.45 +/- 0.39
white     14524    679      > 22.08
v         8490     746      20.45 +/- 0.41
v         13232    126      20.53 +/- 0.33
```
The values quoted above are not corrected for the expected non-negligible Galactic extinction corresponding to a reddening of E(B-V) = 0.10 mag in the direction of the burst (Schlegel et al. 1998).
GCN Circular #7199
B. Sbarufatti, V. Mangano (INAF-IASF PA) report on behalf of the Swift-XRT team:
We have analyzed the 3.9 ks of data of the ToO observation of GRB 080120, started on Jan 20 at 19:47 UT. The refined position of the X-ray source is
```
  Ra (J2000):  15h 01m 03.14s
Dec (J2000): -10d 52' 30.7"
```
with an uncertainty of 3.7 arcsec (radius, 90% confidence). This is 1.1 arcsec away from the first XRT position given in Sbarufatti & Mangano (GCN Circ. 7195), 47.2 arcsec from the initial INTEGRAL position of Mereghetti et al. (GCN Circ. 7194), and 2.2 arcsec from the optical counterparts reported by Kruehler et al. (GCN Circ, 7197) and by Schady & Sbarufatti (GCN Circ. 7198).
The light curve shows an initial flare between 8 and 9 ks from the trigger, followed by a very steep decay (slope 2.9 +/- 0.4). At this decay rate the source will be at a level of 3E-4 counts/s today at 17:30 UT.
The average spectrum can be modeled by an absorbed powerlaw with photon index 2.5 +/- 0.3 with a column density of (1.5 +/- 0.6)E21 cm^-2, sligthly in excess with respect to the Galactic value (7.7E20 cm^-2). The observed (unabsorbed) 0.3-10 keV flux is 4.7E-12 (8.2E-12) ergs cm^-2 s^-1.
This circular is an official product of the Swift-XRT team.
GCN Circular #7200
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 080120 (GCN 7194) at a frequency of 8.46 GHz on 2008 January 8th at 21.72 UT. The GRB is undetected and the 2-sigma upper limit on the peak radio flux at the SWIFT-XRT position (GCN 7199) is 100 uJy (rms 50 uJy).
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc."
GCN Circular #7202
T. Kruehler, J. Greiner, S. McBreen, S. Loew, A. Kuepcue-Yoldas, C. Clemens, A. Yoldas (all MPE Garching) report on behalf of the GROND team:
We observed the field of the INTEGRAL burst GRB 080120 (Mereghetti et al. 2008, GCN #7194) with the 2.2 m MPI/ESO telescope equipped with the multi-channel imager GROND. Observations started at 07:04 UTC on the 22nd of January at an airmass of 2.5 and seeing around 1.0".
The optical/NIR source (Kruehler et al. 2008, GCN #7197, P. Schady et al. 2008, GCN #7198) inside the XRT-error circle (Sbarufatti et al. 2008, GCN #7195) is still detected, and clearly fading. Fitting a power-law to the two epochs yields a slope around 1.5.
A finding chart will be posted at: www.mpe.mpg.de/~jcg/grb080120.html

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Jochen Greiner, last update: 22-Jan-2008 [Disclaimer]