Gamma-ray Burst 090817

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 17 Aug 09 00:51:42 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      49
TRIGGER_NUM:     272163088     
GRB_RA:           88.233d {+05h 52m 56s} (J2000),
                  88.428d {+05h 53m 43s} (current),
                  87.220d {+05h 48m 53s} (1950)
GRB_DEC:         +53.267d {+53d 15' 60"} (J2000),
                 +53.268d {+53d 16' 05"} (current),
                 +53.256d {+53d 15' 20"} (1950)
GRB_ERROR:       9.67 [deg radius, statistical plus systematic] 
GRB_INTEN:       203 [cnts/sec]
DATA_SIGNIF:     13.30 [sigma] 
INTEG_TIME:      2.048 [sec]
GRB_DATE:        15060 TJD;   229 DOY;   09/08/17
GRB_TIME:        3086.21 SOD {00:51:26.21} UT
GRB_PHI:         288.00 [deg]  
GRB_THETA:        65.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]  
HARD_RATIO:      0.13
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  GRO_J0422_32
DETECTORS:       0,0,0, 1,1,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       146.57d {+09h 46m 17s}  +13.43d {+13d 25' 56"} 
SUN_DIST:         60.45 [deg]   Sun_angle= 3.9 [hr] (West of Sun)
MOON_POSTN:       97.76d {+06h 31m 03s}  +25.17d {+25d 10' 12"} 
MOON_DIST:        28.96 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:      159.43, 13.36 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       88.78, 29.83 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.
COMMENTS:        This trigger occurred at longitude,latitude = 171.87,-14.88 [deg].

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Mon 17 Aug 09 00:51:46 UT
NOTICE_TYPE:    INTEGRAL Wakeup
TRIGGER_NUM:    5908,   Sub_Num: 0
GRB_RA:          63.9928d {+04h 15m 58s} (J2000),
                 64.1629d {+04h 16m 39s} (current),
                 63.1110d {+04h 12m 27s} (1950)
GRB_DEC:        +44.1267d {+44d 07' 36"} (J2000),
                +44.1501d {+44d 09' 00"} (current),
                +44.0027d {+44d 00' 10"} (1950)
GRB_ERROR:      3.05 [arcmin, radius, statistical only]
GRB_INTEN:      9.93 [sigma]
GRB_TIME:       3086.88 SOD {00:51:26.88} UT
GRB_DATE:       15060 TJD;   229 DOY;   09/08/17
SC_RA:           64.93 [deg] (J2000)
SC_DEC:          46.73 [deg] (J2000)
SUN_POSTN:      146.57d {+09h 46m 17s}  +13.43d {+13d 25' 56"}
SUN_DIST:        75.29 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      97.76d {+06h 31m 03s}  +25.17d {+25d 10' 12"}
MOON_DIST:       33.16 [deg]
GAL_COORDS:     157.05, -4.78 [deg] galactic lon,lat of the burst
ECL_COORDS:      70.09, 22.47 [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/FERMI NOTICE
NOTICE_DATE:     Mon 17 Aug 09 00:51:55 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      59
TRIGGER_NUM:     272163088     
GRB_RA:           67.217d {+04h 28m 52s} (J2000),
                  67.391d {+04h 29m 34s} (current),
                  66.314d {+04h 25m 15s} (1950)
GRB_DEC:         +45.783d {+45d 46' 60"} (J2000),
                 +45.804d {+45d 48' 14"} (current),
                 +45.673d {+45d 40' 24"} (1950)
GRB_ERROR:       8.12 [deg radius, statistical plus systematic] 
GRB_INTEN:       186 [cnts/sec]
DATA_SIGNIF:     17.00 [sigma] 
INTEG_TIME:      4.096 [sec]
GRB_DATE:        15060 TJD;   229 DOY;   09/08/17
GRB_TIME:        3086.21 SOD {00:51:26.21} UT
GRB_PHI:         293.00 [deg]  
GRB_THETA:        80.00 [deg]  
DATA_TIME_SCALE: 4.0960 [sec]  
HARD_RATIO:      0.50
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      77%  GRB
2nd_MOST_LIKELY:  18%  GRO_J0422_32
DETECTORS:       0,0,0, 1,1,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       146.57d {+09h 46m 17s}  +13.43d {+13d 25' 56"} 
SUN_DIST:         72.91 [deg]   Sun_angle= 5.3 [hr] (West of Sun)
MOON_POSTN:       97.76d {+06h 31m 04s}  +25.17d {+25d 10' 11"} 
MOON_DIST:        31.87 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:      157.48, -2.00 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       72.85, 23.69 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.
COMMENTS:        This trigger occurred at longitude,latitude = 171.87,-14.88 [deg].

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Mon 17 Aug 09 00:51:53 UT
NOTICE_TYPE:    INTEGRAL Refined
TRIGGER_NUM:    5908,   Sub_Num: 1
GRB_RA:          63.9653d {+04h 15m 52s} (J2000),
                 64.1354d {+04h 16m 32s} (current),
                 63.0836d {+04h 12m 20s} (1950)
GRB_DEC:        +44.1233d {+44d 07' 24"} (J2000),
                +44.1467d {+44d 08' 48"} (current),
                +43.9991d {+43d 59' 57"} (1950)
GRB_ERROR:      2.55 [arcmin, radius, statistical only]
GRB_INTEN:      30.36 [sigma]
GRB_TIME:       3092.88 SOD {00:51:32.88} UT
GRB_DATE:       15060 TJD;   229 DOY;   09/08/17
SC_RA:           64.93 [deg] (J2000)
SC_DEC:          46.73 [deg] (J2000)
SUN_POSTN:      146.57d {+09h 46m 17s}  +13.43d {+13d 25' 56"}
SUN_DIST:        75.31 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      97.76d {+06h 31m 04s}  +25.17d {+25d 10' 11"}
MOON_DIST:       33.18 [deg]
GAL_COORDS:     157.03, -4.80 [deg] galactic lon,lat of the burst
ECL_COORDS:      70.06, 22.47 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Possibly real GRB event

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 17 Aug 09 00:52:41 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     272163088     
GRB_RA:           65.890d {+04h 23m 34s} (J2000),
                  66.054d {+04h 24m 13s} (current),
                  65.039d {+04h 20m 09s} (1950)
GRB_DEC:         +39.830d {+39d 49' 48"} (J2000),
                 +39.852d {+39d 51' 07"} (current),
                 +39.714d {+39d 42' 52"} (1950)
GRB_ERROR:       3.86 [deg radius, statistical only]
DATA_SIGNIF:     17.10 [sigma] 
DATA_INTERVAL:   2.048 [sec]   
GRB_DATE:        15060 TJD;   229 DOY;   09/08/17
GRB_TIME:        3086.21 SOD {00:51:26.21} UT
GRB_PHI:         298.00 [deg]  
GRB_THETA:        83.00 [deg]  
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   413 (Gnd S/W Version number)
SUN_POSTN:       146.57d {+09h 46m 17s}  +13.43d {+13d 25' 55"}
SUN_DIST:         74.22 [deg]   Sun_angle= 5.4 [hr] (West of Sun)
MOON_POSTN:       97.77d {+06h 31m 06s}  +25.17d {+25d 10' 07"} 
MOON_DIST:        30.28 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:      161.10, -6.83 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       70.74, 17.99 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 17 Aug 09 00:52:46 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      69
TRIGGER_NUM:     272163088     
GRB_RA:           64.010d {+04h 16m 02s} (J2000),
                  64.172d {+04h 16m 41s} (current),
                  63.172d {+04h 12m 41s} (1950)
GRB_DEC:         +38.390d {+38d 23' 24"} (J2000),
                 +38.413d {+38d 24' 48"} (current),
                 +38.266d {+38d 15' 58"} (1950)
GRB_ERROR:       2.91 [deg radius, statistical only]
DATA_SIGNIF:     17.30 [sigma] 
DATA_INTERVAL:   4.096 [sec]   
GRB_DATE:        15060 TJD;   229 DOY;   09/08/17
GRB_TIME:        3086.21 SOD {00:51:26.21} UT
GRB_PHI:         299.00 [deg]  
GRB_THETA:        85.00 [deg]  
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   413 (Gnd S/W Version number)
SUN_POSTN:       146.57d {+09h 46m 17s}  +13.43d {+13d 25' 55"}
SUN_DIST:         75.81 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:       97.77d {+06h 31m 06s}  +25.17d {+25d 10' 06"} 
MOON_DIST:        31.25 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:      161.09, -8.88 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       68.97, 16.83 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Mon 17 Aug 09 00:54:44 UT
NOTICE_TYPE:    INTEGRAL Refined
TRIGGER_NUM:    5908,   Sub_Num: 2
GRB_RA:          63.9657d {+04h 15m 52s} (J2000),
                 64.1358d {+04h 16m 33s} (current),
                 63.0840d {+04h 12m 20s} (1950)
GRB_DEC:        +44.1233d {+44d 07' 24"} (J2000),
                +44.1467d {+44d 08' 48"} (current),
                +43.9991d {+43d 59' 57"} (1950)
GRB_ERROR:      2.55 [arcmin, radius, statistical only]
GRB_INTEN:      30.09 [sigma]
GRB_TIME:       3093.71 SOD {00:51:33.71} UT
GRB_DATE:       15060 TJD;   229 DOY;   09/08/17
SC_RA:           64.93 [deg] (J2000)
SC_DEC:          46.73 [deg] (J2000)
SUN_POSTN:      146.57d {+09h 46m 18s}  +13.43d {+13d 25' 53"}
SUN_DIST:        75.31 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      97.80d {+06h 31m 11s}  +25.17d {+25d 09' 56"}
MOON_DIST:       33.20 [deg]
GAL_COORDS:     157.03, -4.80 [deg] galactic lon,lat of the burst
ECL_COORDS:      70.07, 22.47 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Possibly real GRB event

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Mon 17 Aug 09 02:16:59 UT
NOTICE_TYPE:    INTEGRAL Offline
TRIGGER_NUM:    5908,   Sub_Num: 3
GRB_RA:          63.9657d {+04h 15m 52s} (J2000),
                 64.1358d {+04h 16m 33s} (current),
                 63.0840d {+04h 12m 20s} (1950)
GRB_DEC:        +44.1233d {+44d 07' 24"} (J2000),
                +44.1467d {+44d 08' 48"} (current),
                +43.9991d {+43d 59' 57"} (1950)
GRB_ERROR:      2.60 [arcmin, radius, statistical only]
GRB_INTEN:      30.09 [sigma]
GRB_TIME:       3093.71 SOD {00:51:33.71} UT
GRB_DATE:       15060 TJD;   229 DOY;   09/08/17
SC_RA:           64.93 [deg] (J2000)
SC_DEC:          46.73 [deg] (J2000)
SUN_POSTN:      146.63d {+09h 46m 30s}  +13.41d {+13d 24' 48"}
SUN_DIST:        75.36 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      98.72d {+06h 34m 52s}  +25.05d {+25d 02' 49"}
MOON_DIST:       33.89 [deg]
GAL_COORDS:     157.03, -4.80 [deg] galactic lon,lat of the burst
ECL_COORDS:      70.07, 22.47 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       refined_coordinates_after_offline_analysis

GCN Circular #9815
V.Beckmann (ISDC, Versoix), D.Gotz (CEA-Saclay), S.Mereghetti, A.Paizis (IASF-Milano), A. Neronov, M. Beck (ISDC, Versoix), and J. Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report:
A long GRB with duration of about 250 s has been detected by IBAS in IBIS/ISGRI data at 00:51:33 UT on August 17th.
The refined coordinates (J2000) are:
```
   RA:   63.9659 [degrees]
   DEC: +44.1234 [degrees]
```
with an uncertainty of 2.6 arcmin (90% c.l.).
The light curve shows two prominent peaks at T0 and at T0+196s. 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 #9819
P.A. Evans (U. Leicester), C. Guidorzi (U Ferrara) and W.H. Baumgartner (GSFC/UMBC) report on behalf of the Swift-XRT team:
The Swift-XRT observed the field of GRB 090817 (Beckmann et al. GCN Circ. 9815) from T0+11 ks to T0+17.5 ks gathering 1.8 ks of Photon Counting (PC) mode data.
Inside the INTEGRAL error circle we find a single, uncatalogued X-ray source at RA, Dec = 63.96600, 44.12900 which is equivalent to:
```
RA (J2000):  04 15 51.85
Dec (J2000): +44 07 44.5
```
with an uncertainty of 2.0 arcsec (radius, 90% confidence). The optical source USNO-B1.0 1341-0096763 lies only 1.3 arcsec from the XRT position. This object is point-like in USNO-B1, with magnitudes I=18.5, R=20.0, B=20.8.
The light curve of the X-ray source shows a rapid rise from 0.04 ct/sec at T0+11 ks to 0.1 ct s^-1 at T0+12 ks; by T0+18 ks the count rate has returned to 0.04 ct s^-1. A spectrum formed from the PC mode data can be modelled with an absorbed power law with a photon index of 2.5 (+0.7, -0.6) with an absorption column of 9.5 (+4.9, -4.0) x 10^21 cm^-2, in excess of the Galactic value of 4.0 x 10^21 cm^-2 (Kalberla et al. 2005).
Given the light curve of this source, it is not clear whether or not this is a GRB afterglow. A further observation has therefore been planned, and will take place today.
No other sources are detected in the INTEGRAL error circle, with a 3-sigma upper limit of 5 x 10^-3 ct s^-1. Using the typical counts-to-observed-flux conversion factor from Evans et al (2009, MNRAS, 397, 1177) this gives a flux limit of 1.7 x 10^-13 erg cm^-2 s^1.
This circular is an official product of the Swift-XRT team.
GCN Circular #9822
A. Breeveld (MSSL/UCL) and W. Baumgartner (GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 090817 11008 s after the INTEGRAL trigger (Beckmann et al., GCN Circ. 9815). No new sources are found in the UVOT data at the position of the XRT source (P.A. Evans et al., GCN Circ. 9819). Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) and a 3 arcsec radius aperture, for the initial summed exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white         11516        17719          413         >21.3
v                11975        12398          416         >19.6
b                11058        17509          787         >21.2
u                11008        17157           78         >19.5
```
The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.66 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #9823
Colleen A. Wilson-Hodge (NASA/MSFC) reports on behalf of the Fermi GBM Team:
"At 00:51:26.21 UT on 17 August 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090817 (trigger 272163088 / 090817036). which was also detected by INTEGRAL (Beckmann et al. 2009, GCN 9815) The GBM on-ground location is consistent with the INTEGRAL position.
The angle from the Fermi LAT boresight is 82 degrees.
The GBM light curve consists of an initial bright peak at the trigger time followed by a weak broad bump about 200 s after the trigger. This burst has a duration (T90) of about 220 s (8-1000 keV).
Spectral analysis was performed only for the bright initial peak. The time-averaged spectrum from T0 to T0+41 s is adequately fit by a Band function with Epeak = 115 +/- 50 keV, alpha = -1.1 +/- 0.3, and beta = -2.2 +/- 0.6
The event fluence (8-1000 keV) over the T90 interval is (7.3 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.15 s in the 8-1000 keV band is 3.8 +/- 0.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #9825
P.A. Evans (U. Leicester), C. Guidorzi (U Ferrara) and W.H. Baumgartner (GSFC/UMBC) report on behalf of the Swift-XRT team:
Swift conducted a second observation of GRB 090817 (Beckmann et al. GCN Circ. 9815), collecting 3.9 ks of Photon Counting (PC) mode XRT data in the interval T0+50 ks to T0+58 ks. The source reported by Evans et al. (GCN Circ. 9819) has faded to a level of ~0.015 ct s^-1. A power-law fit to the light curve yields a temporal decay index of alpha=0.9+/-0.2
Inspecting the USNO-B1 catalogue within 3.5' of the GRB we find 216 objects with R2<20.0. The probability of finding a USNO-B1 source within a 2" radius circle in this field is thus 2%. The strength of the potential association between the XRT and USNO-B1 sources noted in GCN Circ. 9819 is therefore fairly weak.
We therefore suggest that the XRT source is the afterglow of GRB 090817.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020108.
This circular is an official product of the Swift-XRT team.
GCN Circular #9826
V. Rumyantsev (CrAO), A. Pozanenko (IKI), M. Andreev (Terskol Branch of Institute of Astronomy) report on behalf of larger GRB follow-up collaboration:
We observed a field of the INTEGRAL GRB 090817 (Beckmann et al., GCN 9815) with Shajn telescope of CrAO starting on Aug. 17 (UT) 01:07, i.e. ~17 minutes after burst onset. A series of 37 images of 60 s exposure was obtained in R filter. Within XRT error circle of the afterglow (Evans et al., GCN 9819, GCN 9825) we do not detect any new object. The quoted USNO-B1.0 star USNO-B1.0 1341-0096763 (Evans et al., GCN 9819) does not change its brightness within ~0.08 m during our observations. An upper limit of a single frame of 60 s exposure is R~21.5 m. Data reduction is continuing.
GCN Circular #9827
GRB 090817: Liverpool Telescope Observations
Z. Cano, I.A. Steele, C.G. Mundell, A. Melandri, S. Kobayashi, C.J. Mottram, R.J. Smith, D. Bersier (Liverpool JMU), A. Gomboc (U. Ljubljana), report on behalf of a large collaboration:
On August 17 2009, 1.459 hours after the burst was detected, the 2-m Liverpool Telescope automatically began observing the INTEGRAL GRB 090817 (Beckmann et al.,GCN Circ. 9815) using g',r' and i' filters.
We do not detect any uncatalogued source inside the Swift-XRT error circle (Evans et al. GCN Circ 9819). Upper limits in stacked R and I images for isolated objects are 20.6 and 20.8 respectively.
Magnitudes have been calibrated from the nearby USNO star (1341-0096766): 04:15:52.314, +44:07:50.9 using R2=17.56 and I=17.04.
We note that the upper limits presented are the limits for detecting an isolated object in our images. As the USNO star (1341-0096763) lies only 1.3" from the XRT position the actual upper limits will be accordingly brighter.

GCN Circular #9828
V. Rumyantsev (CrAO), A. Pozanenko (IKI), M. Andreev (Terskol Branch of Institute of Astronomy) report on behalf of larger GRB follow-up collaboration:
We report a photometry of the USNO-B1.0 object 341-0096763 in the XRT error circle of the X-ray afterglow (Evans et al., GCN 9819, GCN 9825) of the INTEGRAL GRB 090817 (Beckmann et al., GCN 9815). The observations took place with Shajn telescope of CrAO on Aug.17 (Rumyantsev et al., GCN 9826). The photometry is based on the reference star USNO B1.0 1341-0096766 (04 15 48.35 +44 08 07.7) assuming R = 17.54, only statistical errors are quoted. Upper limits are presented for isolated object. To make any conclusion about variability of the star or the presence in the tail of the star other possible source we are planning second epoch observation.

Date        Time start (UT)   Upper_Limit  R_mag

2009-08-17  01 09 36.45  21.5  19.33 +/-0.05
2009-08-17  01 10 40.62  21.5  19.38 +/-0.05
2009-08-17  01 13 23.49  21.7  19.43 +/-0.04
2009-08-17  01 14 27.16  21.7  19.32 +/-0.04
2009-08-17  01 15 30.91  21.8  19.35 +/-0.04
2009-08-17  01 16 34.72  21.9  19.46 +/-0.04
2009-08-17  01 17 38.27  21.9  19.40 +/-0.04
2009-08-17  01 18 41.93  21.9  19.44 +/-0.04
2009-08-17  01 19 45.99  21.7  19.39 +/-0.04
2009-08-17  01 20 49.53  21.7  19.37 +/-0.04
2009-08-17  01 21 53.11  21.8  19.45 +/-0.04
2009-08-17  01 22 58.16  21.7  19.40 +/-0.04
2009-08-17  01 24 01.75  21.8  19.28 +/-0.04
2009-08-17  01 25 05.64  21.8  19.45 +/-0.04
2009-08-17  01 26 09.20  21.8  19.46 +/-0.04
2009-08-17  01 27 12.86  21.8  19.39 +/-0.04
2009-08-17  01 28 16.41  21.8  19.38 +/-0.04
2009-08-17  01 29 22.52  21.6  19.38 +/-0.05
2009-08-17  01 30 26.12  21.6  19.39 +/-0.05
2009-08-17  01 31 29.63  21.6  19.38 +/-0.05
2009-08-17  01 32 33.37  21.7  19.33 +/-0.04
2009-08-17  01 33 38.37  21.6  19.39 +/-0.05
2009-08-17  01 34 42.08  21.6  19.38 +/-0.05
2009-08-17  01 35 45.77  21.6  19.42 +/-0.05
2009-08-17  01 36 49.51  21.5  19.46 +/-0.06
2009-08-17  01 37 53.18  21.4  19.34 +/-0.05
2009-08-17  01 38 56.70  21.3  19.55 +/-0.08
2009-08-17  01 40 00.31  21.3  19.44 +/-0.07
2009-08-17  01 41 06.39  21.2  19.30 +/-0.07
2009-08-17  01 42 12.89  21.2  19.47 +/-0.08
2009-08-17  01 43 16.53  21.1  19.41 +/-0.08
2009-08-17  01 44 20.34  21.1  19.43 +/-0.08
2009-08-17  01 45 24.13  20.9  19.41 +/-0.10
2009-08-17  01 46 28.68  20.9  19.42 +/-0.10
2009-08-17  01 47 32.26  20.7  19.29 +/-0.11
2009-08-17  01 48 35.81  20.7  19.52 +/-0.13

GCN Circular #9831
S. T. Holland (CRESST/GSFC/USRA), A. Breeveld (MSSL/UCL), and W. Baumgartner (GSFC/UMBC) report on behalf of the Swift UVOT team:
The Swift/UVOT observed the field of GRB 090817 (Beckman et al., 2009, GCN Circ. 9815) between 11 ks and 284 ks after the INTEGRAL trigger. The USNO-B1.0 source 1341-0096763 (Evans et al. 2009, GCN Circ. 9819, Rumyantsev et al. 2009, GCN Circ. 9828) is detected inside the XRT error circle (Evans et al., 2009, GCN Circ. 9819). We find no evidence for variability in this source during our observations. Preliminary magnitudes and 3-sigma upper limits from all of the coadded data are
```
Filter    Exposure      Mag  Err Sigma
--------------------------------------
v              416    19.86 0.46   2.4
b              787    20.99 0.33   3.4
u             4003    21.49 0.30   3.7
uvw1          4326   >22.0   ...   ...
white          413    21.19 0.37   3.2
```
The quoted magnitudes and upper limits have not been corrected for the expected Galactic extinction along the line of sight corresponding to a reddening of E_{B-V} = 0.66 mag (Schlegel et al., 1998, ApJS, 500, 525). All photometry is on the UVOT photometry system described in Poole et al. (2008, MNRAS, 383, 627).
The UVOT coordinates of this source are
```
  RA (J2000.0)  04:15:51.85  =   63.96604 (deg)
 Dec (J2000.0) +44:07:44.5   =  +44.12902 (deg)
```
with an estimated uncertainty of 1.0 arcsec (radius, 90% confidence, statistical + systematic). The dereddened colours of the source are not consistent with a stellar spectrum. However, the colours are consistent with an Sm or Im galaxy (de Vaucouleurs, 1961, ApJS, 5, 233). This suggests that the source may be the host galaxy of GRB 090817. If this galaxy has an absolute magnitude similar to that of the LMC then it is located at a redshift of approximately z = 0.05. An intrinsically fainter galaxy would be closer. Follow-up spectroscopy is encouraged to verify this.
GCN Circular #9834
S. T. Holland (CRESST/GSFC/USRA), A. Breeveld (MSSL/UCL), and W. Baumgartner (GSFC/UMBC) report on behalf of the Swift UVOT team:
Swift/UVOT observed the USNO-B1.0 source 1341-0096763 (Evans et al. 2009, GCN Circ. 9819; Rumyantsev et al. 2009, GCN Circ. 9828; Holland et al. 2009, GCN Circ. 9831), which is located inside the XRT error circle (Evans et al., 2009, GCN Circ. 9819), at approximately 6 and 7 days after the INTEGRAL trigger (Beckman et al., 2009, GCN Circ. 9815). A preliminary examination of the UVOT data yields weak evidence that the source may have brightened by approximately 0.5 mag in the UVOT v band between approximately 6.5 and 7.1 days. Our observations are consistent with a supernova rising to maximum light. However, we stress that further observations are needed to confirm this. Follow-up photometric and spectroscopic observations of this source are strongly encouraged.
GCN Circular #9837
J. P. Halpern and J. Ruan (Columbia U.) report:
We obtained R-band photometry of the USNO-B1.0 object 341-0096763 on 2009 August 21 10:46 UT using the McGraw Hill 1.3m telescope. In five 300 s exposures in seeing of 1.5"-1.8", there is no evidence to support the hypothesis of Holland et al. (GCN Circ. 9831) that this object is the host galaxy of GRB 090817. The image is consistent with the stellar point spread function. Using the reference star of Rumyantsev et al. (GCN Circ. 9828), we measure R = 19.39+/-0.04, consistent with their photometry on Aug. 17.
On Aug. 25 09:56 UT, we again obtained five 300 s exposures in seeing of 1.5". We measure R = 19.42+/-0.03, 8.4 days after the burst, which is consistent with all previous measurements. Thus, there is no evidence for brightening suggested by Holland et al. (GCN Circ. 9834) from Swift UVOT observations between 6.5 and 7.1 days. The set of consistent magnitudes from day zero in GCN Circ. 9828 to days 4 and 8 in this report are indicative of a chance coincidence with a normal star.
GCN Circular #9841
S. B. Cenko, L. M. Walkowicz (UC Berkeley), M. M. Kasliwal, V. Bhalero, S. R. Kulkarni, F. A. Harrison (Caltech), I. Arcavi (Weizmann Institute) and W. H. Baumgartner (GSFC/UMBC) report on behalf of a larger collaboration:
We have obtained a spectrum of the putative host galaxy of GRB09817 (Holland et al., GCNs 9831 and 9834) with the Low Resolution Imaging Spectrometer mounted on the 10 m Keck I telescope. Our spectra were taken in twilight conditions at Aug 25.55 UT and cover a wavelength range from 3500 - 9000 A.
After correcting for the large Galactic extinction, the source exhibits a blue continuum with superposed absorption features from the H Balmer series (H-alpha, -beta, -gamma, and -delta) and Ca (H+K and the NIR triplet), all consistent with their rest wavelengths. As suggested by Halpern and Ruan (GCN 9837), the object is therefore a foreground star (likely a hot, ~ A-type) and likely unrelated to GRB090817.
GCN Circular #9842
D. A. Kann, F. Cusano and F. Ludwig (TLS Tautenburg) report:
We observed the field of the INTEGRAL/Fermi GRB 090817 (Beckmann et al., GCN 9815, Wilson-Hodge, GCN 9823) with the 1.34m Tautenburg Schmidt telescope under good conditions. We obtained 3 x 600 sec Rc images at a mid-time of 8.015 days after the GRB.
At the position of the X-ray afterglow (Evans, Guidorzi & Baumgartner, GCN 9819, GCN 9825), the USNO-B1.0 object 1341-0096763 is clearly detected. Using the comparison star of Rumyantsev, Pozanenko & Andreev (GCN 9828), we find Rc = 19.54 +/- 0.03 mag. This is in agreement with the reports of non-variability (Rumyantsev, Pozanenko & Andreev, GCN 9828, Halpern & Ruan, GCN 9837) of this proposed host galaxy/SN candidate (Holland, Breeveld & Baumgartner, GCN 9831, GCN 9834), and a stellar PSF is in full agreement with it being a foreground star (Halpern & Ruan, GCN 9837, Cenko et al., GCN 9841).
No further observations are planned.
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Jochen Greiner, last update: 27-Aug-2009 [Disclaimer]