GRB081221A

This page lists all entries on GRB081221A in GRBweb

Summary Fermi GBM IPN Swift GCN 8687 GCN 8688 GCN 8689 GCN 8690 GCN 8694 GCN 8698 GCN 8700 GCN 8701 GCN 8703 GCN 8704 GCN 8708 GCN 8711 GCN 8719 GCN 8741 GCN 8748

Summary table
Variable Value Source
GRB_name_Fermi GRB081221681
T0 16:21:11 UTC GCN_circulars,Swift Det
ra 15.7927° Swift
decl -24.5481° Swift
pos_error 1.81e-04° Swift
T90 29.697 s Fermi_GBM
T90_error 0.41 s Fermi_GBM
T90_start 16:21:15.546 UTC Fermi_GBM
fluence 3.00e-05 erg/cm² Fermi_GBM
fluence_error 8.69e-08 erg/cm² Fermi_GBM
redshift 2.2600
T100 34.243 s
GBM_located False
mjd 54821.68137731482 GCN_circulars,Swift Det
Fermi GBM table
GRB_name_Fermi GRB081221681
trigger_name bn081221681
ra 15.8000°
decl -24.5000°
pos_error 2.52e+00°
datum 2008-12-21
t_trigger 16:21:12.218 UTC
T90 29.697 s
T90_error 0.41 s
T90_start 16:21:15.546 UTC
fluence 3.00e-05 erg/cm²
fluence_error 8.69e-08 erg/cm²
flux_1024 2.54e+01 erg/cm²/s
flux_1024_error 3.26e-01 erg/cm²/s
flux_1024_time 2.09e+01 erg/cm²/s
flux_64 2.75e+01 erg/cm²/s
flux_64_error 1.36e+00 erg/cm²/s
IPN table
GRB_name GRB081221A
ra 15.8042°
decl -24.5333°
pos_error 5.00e-02°
redshift 2.2600
Swift table
GRB_name GRB081221A
t_trigger 16:21:11 UTC
ra 15.7927°
decl -24.5481°
pos_error 1.81e-04°
T90 34.0 s
fluence 1.81e-05 erg/cm²
redshift 2.2600
GCN 8687 table
GRB_name GRB081221A
GCN_number 8687
Detection_method Swift Det
t_trigger 16:21:11 UTC
ra 15.8050°
decl -24.5260°
Circular_text TITLE: GCN CIRCULAR NUMBER: 8687 SUBJECT: GRB 081221: Swift detection of a burst DATE: 08/12/21 16:42:05 GMT FROM: David Burrows at PSU/Swift E. A. Hoversten (PSU), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), J. A. Kennea (PSU), V. Mangano (INAF-IASFPA), C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), D. M. Palmer (LANL), J. L. Racusin (PSU), P. Romano (INAF-IASFPA), B. A. Rowlinson (U Leicester), M. C. Stroh (PSU), G. Tagliaferri (INAF-OAB), T. N. Ukwatta (GSFC/GWU) and L. Vetere (PSU) report on behalf of the Swift Team: At 16:21:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 081221 (trigger=337889). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 15.805, -24.526 which is RA(J2000) = 01h 03m 13s Dec(J2000) = -24d 31' 32" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed two peaks, at T+0 to T+10 seconds and a much larger one at T+15 to T+40 seconds. The peak count rate was ~20000 counts/sec (15-350 keV), at 22 sec after the trigger. The XRT began observing the field at 16:22:20.2 UT, 68.4 seconds after the BAT trigger. XRT found a bright, fading, uncatalogued X-ray source located at RA, Dec 15.7934, -24.5484 which is equivalent to: RA(J2000) = 01h 03m 10.41s Dec(J2000) = -24d 32' 54.2" with an uncertainty of 5.0 arcseconds (radius, 90% containment). This location is 89 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 0.1 s image was 7.36e-08 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 78 seconds after the BAT trigger, and a finding chart exposure of 250 seconds with the u filter starting 290 seconds after the trigger. No credible 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 at the XRT position is 19.9 mag in White, 19.8 mag in u. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02. We note that this burst is coincident with a Fermi GBM burst (trigger 251569273). Burst Advocate for this burst is E. A. Hoversten (hoversten AT astro.psu.edu). 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.)
GCN 8688 table
GRB_name GRB081221A
GCN_number 8688
Detection_method Other
ra 15.7927°
decl -24.5465°
Circular_text TITLE: GCN CIRCULAR NUMBER: 8688 SUBJECT: GRB 081221: NOT observations DATE: 08/12/21 20:13:16 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst Daniele Malesani, Johan P. U. Fynbo (DARK/NBI), Eric Stempels (Univ. St. Andrews), and Tapio Pursimo (NOT), report on behalf of a larger collaboration: We observed the field of GRB 081221 (Hoversten et al., GCN 8687) with the NOT equipped with ALFOSC. R-band imaging was carried out (12 min exposure) with mean time Dec 21.81 UT (3.14 hr after the GRB). Inside the XRT error circle (Hoversten et al., GCN 8687), we detect no source down to a limiting magnitude R ~ 23. Further imaging is ongoing. We note the presence of two faint sources just outside the XRT error circle, at approximate coordinates (J2000): 1: RA = 01:03:10.26, Dec = -24:32:47.4, R ~ 22.3 2: RA = 01:03:10.10, Dec = -24:32:58.6, R ~ 23.0 We acknowledge excellent support from the NOT staff.
GCN 8689 table
GRB_name GRB081221A
GCN_number 8689
Detection_method Optical
ra 15.7900°
decl -24.5458°
Circular_text TITLE: GCN CIRCULAR NUMBER: 8689 SUBJECT: GRB 081221: further NOT observations DATE: 08/12/21 22:12:49 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst Daniele Malesani, Johan P. U. Fynbo (DARK/NBI), Tapio Pursimo (NOT), and Eric Stempels (Univ. St. Andrews) report on behalf of a larger collaboration: Further to what reported in GCN 8688, we observed the field of GRB 081221 (Hoversten et al., GCN 8687) in the I and z filters with the NOT equipped with ALFOSC. Exposure times were 18 and 16 min, respectively, with mean times Dec 21.844 and Dec 21.863 UT (3.89 and 4.37 hr after the GRB, respectively). Inside the XRT error circle reported by Hoversten et al. (GCN 8687), we do not detect any source in either filters. The limiting magnitude is I ~ 23 assuming I = 17.65 for the USNO star at RA = 01:03:09.59, Dec = -24:32:45.0. We encourage deeper searches of the optical/NIR counterpart of this event, which had a bright gamma- and X-ray prompt emission.
GCN 8690 table
GRB_name GRB081221A
GCN_number 8690
Detection_method Swift-XRT Det
ra 15.7925°
decl -24.5481°
Circular_text TITLE: GCN CIRCULAR NUMBER: 8690 SUBJECT: GRB 081221: Enhanced Swift-XRT position DATE: 08/12/22 03:22:16 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 4345 s of XRT Photon Counting mode data and 7 UVOT images for GRB 081221, 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 = 15.7925, -24.5481 which is equivalent to: RA (J2000): 01h 03m 10.20s Dec (J2000): -24d 32' 53.1" with an uncertainty of 1.4 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.
GCN 8694 table
GRB_name GRB081221A
GCN_number 8694
Detection_method Konus-Wind Det
t_trigger 16:21:14.915 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 8694 SUBJECT: Konus-Wind observation of GRB 081221 DATE: 08/12/22 11:05:55 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, D. Svinkin, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team report: The long GRB 081221 (Hoversten et al., GCN 8687) triggered Konus-Wind at T0=58874.915 s UT (16:21:14.915). The burst light curve shows two multipeaked pulses with a total duration of ~40 s. As observed by Konus-Wind the burst had a fluence of (2.28 +/- 0.07)x10^-5 erg/cm2, and a 256-ms peak flux measured from T0+19.824 s of (1.75 +/- 0.16)x10^-6 erg/cm2/s (both in the 20 keV - 1 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+39.424 s) can be fitted (in the 20 keV-1 MeV range) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.91(-0.14, +0.15), and Ep = (83 +/- 4) keV (chi2 = 67.4/51 dof). Fitting by GRB (Band) model yields the same alpha and Ep, and only an upper limit on the high energy photon index: beta < -3.48 (chi2 = 67.4/50 dof). Thus, it is a bright and soft GRB. All the quoted errors are at the 90% confidence level. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB081221_T58874/
GCN 8698 table
GRB_name GRB081221A
GCN_number 8698
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 8698 SUBJECT: GRB 081221: Gemini-N nIR imaging DATE: 08/12/22 13:49:28 GMT FROM: Nial Tanvir at IofA U.Cambridge N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick), K. Wiersema (U. Leicester), A. S. Fruchter, J. Graham (STScI) report: We observed the field of GRB 081221 with Gemini-N/NIRI, starting 22 Dec 2008 04:20UT, approximately 12 hours post burst. Our preliminary analysis reveals a faint point source in the enhanced XRT error circle (GCN 8690) with magnitude K~20.1 at position: 01:03:10.19 -24:32:52.2 relative to three 2MASS stars in the field. The source is also marginally detected in J and H. We suggest this is most likely the afterglow of GRB 081221, but that its faintness and red colour (H-K>~2) argue for a dusty sight-line rather than a high redshift as the explanation for the absence of an optical detection (GCN 8688 and GCN 8689). Further analysis is ongoing. We thank Ricardo Schiavon (Gemini) for his assistance in obtaining these observations.
GCN 8700 table
GRB_name GRB081221A
GCN_number 8700
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 8700 SUBJECT: GRB 081221: pseudo-redshift (pz=0.7) from the spectral parameters of the prompt emission DATE: 08/12/22 14:02:52 GMT FROM: Jean-Luc Atteia at Lab d Astrophys.,OMP,Toulouse A. Pelangeon and J-L. Atteia (LATT-OMP) report: We have used the spectral parameters of GRB 081221 provided by Golenetskii et al. (GCN Circ. 8694) to compute the spectral pseudo-redshift** of this burst detected by Swift-BAT (Hoversten et al. GCNC 8687). We find a pseudo-redshift pz = 0.7 +/- 0.1 ** http://cosmos.ast.obs-mip.fr/projet/index.html
GCN 8701 table
GRB_name GRB081221A
GCN_number 8701
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 8701 SUBJECT: GRB 081221: Swift-XRT Refined Analysis DATE: 08/12/22 14:26:07 GMT FROM: Michael Stroh at PSU/Swift M.C. Stroh and E. A. Hoversten (PSU) report on behalf of the Swift-XRT team: We have analyzed the first seven orbits of XRT data from GRB 081221 (Hoversten et al., GCN 8687) beginning 73s after the trigger. The Swift-XRT data consists of 803s in Windowed Timing (WT) mode and 5.9ks in Photon Counting (PC) mode. The enhanced XRT position for this burst was reported by Evans et al. (GCN Circ. 8690). The X-ray light curve begins with count rates near 10^3 cts/s and has an early flare reaching 1130 cts/s at T+103s. Following the flare, the light curve can be modeled with a double broken power-law with initial decay rate of 5.48 +/- 0.08, initial break time at T+207s, second decay rate of 0.68 +/- 0.20, second break time at T+896s, and a final decay rate of 1.35 +/- 0.04. If the light curve follows the same decline, we predict count rates at T+24hr and T+48hr to be 1.6e-2 and 6.4e-3 respectively. The time-averaged WT spectrum can be fit with an absorbed power law with photon index Gamma = 1.994 (+/-0.014) and nH of 3.24 (+/- 0.05) e21 cm^-2 which is in excess of the Galactic value of 2.03e20 cm^-2 (Kalberla et al. 2005). The absorbed (unabsorbed) 0.3-10.0 keV flux is 2.44 (3.86) e-9 ergs/cm^2/s. The time-averaged PC spectrum can be fit with an absorbed power law with photon index Gamma = 2.37 (+/-0.15) and nH of 3.5 (+/-0.5) e21 cm^-2. The absorbed (unabsorbed) 0.3-10.0 keV flux is 1.04 (2.17) e-11 ergs/cm^2/s. This circular is an official product of the Swift-XRT team.
GCN 8703 table
GRB_name GRB081221A
GCN_number 8703
Detection_method Swift-UVOT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 8703 SUBJECT: Swift/UVOT observations of GRB 081221 DATE: 08/12/22 14:56:47 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (MSSL/UCL) and E. A. Hoversten (PSU) report on behalf of the Swift UVOT team. The Swift UltraViolet/Optical Telescope (UVOT) began settled observations of GRB081221 (Swift BAT trigger number 337889, Hoversten et al., GCN Circ. 8687), on December 21, 2008, at 16:22:29, 78 seconds after the trigger with a white finding chart. We do not detect any new source at the enhanced XRT position reported in GCN Circ. 8690 (Evans et al.). The observed magnitude upper limits for GRB 081221 are given below for the first observations and the summed exposures in the UVOT filters: Filter Tstart(s) Tstop(s) Exp(s) Magnitude wh 78 228 149.8 >20.84 (3-sigma UL) v 619 639 19.4 >17.89 (3-sigma UL) b 545 565 19.4 >18.85 (3-sigma UL) u 290 540 245.8 >20.15 (3-sigma UL) uvw1 668 688 19.4 >18.10 (3-sigma UL) uvm2 644 664 19.5 >17.71 (3-sigma UL) uvw2 595 615 19.4 >18.08 (3-sigma UL) wh 78 6086 381.0 >21.41 (3-sigma UL) v 59 34696 2192.4 >20.74 (3-sigma UL) b 545 41269 1765.2 >21.55 (3-sigma UL) u 290 40478 3667.7 >21.69 (3-sigma UL) uvw1 668 39565 3758.4 >21.57 (3-sigma UL) uvm2 644 45178 3409.4 >21.55 (3-sigma UL) uvw2 595 33783 2005.6 >21.35 (3-sigma UL) The values quoted above are on the UVOT Photometric System (Poole et al, 2008, MNRAS 383,627). They are not corrected for the expected galactic reddening of E(B-V) = 0.021 in the direction of the burst (Schlegel et al. 1998).
GCN 8704 table
GRB_name GRB081221A
GCN_number 8704
Detection_method Fermi GBM Det
t_trigger 16:21:12.220 UTC
ra 17.2000°
decl -24.8000°
Circular_text TITLE: GCN CIRCULAR NUMBER: 8704 SUBJECT: GRB081221: Fermi GBM observation DATE: 08/12/22 16:09:29 GMT FROM: Colleen A. Wilson at NASA/MSFC/NSSTC Colleen A. Wilson-Hodge (NASA/MSFC) reports on behalf of the Fermi GBM Team: "At 16:21:12.22 UT on 21 December 2008, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 081221 (trigger 251569273 / 081221681), which was also detected by the SWIFT-BAT and XRT (Hoversten et al. 2008, GCN 8687). The on-ground calculated location, using the GBM trigger data, is RA = 17.2, DEC = -24.8 (J2000 degrees, equivalent to 01 h 09 m, -24 d 50'), with an uncertainty of less than 1.0 degree (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 78 degrees. The GBM light curve consists of a weak initial peak and a bright second peak with a duration (T90) of about 40 s (8-1000 keV). The time-averaged spectrum from T0+0.003 s to T0+38.401 s is adequately fit by a Band function with Epeak = 77 +/- 1 keV, alpha = -0.42 +/- 0.03, and beta = -2.91 +/- 0.08. These spectral parameters are consistent with Konus-Wind observations (Golenetskii et al. 2008, GCN 8694.) The event fluence (8-1000 keV) in this time interval is (3.7 +/- 0.1)E-05 erg/cm^2. The 64-msec peak photon flux measured starting from T0+19.3923 s in the 8-1000 keV band is 33 +/- 9 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN 8708 table
GRB_name GRB081221A
GCN_number 8708
Detection_method Swift-BAT Det
ra 15.8010°
decl -24.5420°
Circular_text TITLE: GCN CIRCULAR NUMBER: 8708 SUBJECT: GRB 081221, Swift-BAT refined analysis DATE: 08/12/22 19:27:08 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), E. A. Hoversten (PSU), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+873 sec from the recent telemetry downlink, we report further analysis of BAT GRB 081221 (trigger #337889) (Hoversten, et al., GCN Circ. 8687). The BAT ground-calculated position is RA, Dec = 15.801, -24.542 deg which is RA(J2000) = 01h 03m 12.2s Dec(J2000) = -24d 32' 32.8" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 61%. The mask-weighted light curve shows two main overlapping peaks, the smaller from about T+0 to T+12 sec and the larger from about T+12 to T+40 sec, with multiple subsidiary peaks and an extended tail visible to about T+150 sec. T90 (15-350 keV) is 34 +- 1 sec (estimated error including systematics). The time-averaged spectrum from T-0.3 to T+112.6 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.21 +- 0.13, and Epeak of 69.9 +- 3.9 keV (chi squared 37.73 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.81 +- 0.03 x 10-05 erg/cm2 and the 1-sec peak flux measured from T+21.42 sec in the 15-150 keV band is 18.2 +- 0.5 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.86 (chi squared 119.90 for 57 d.o.f.). 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/337889/BA/
GCN 8711 table
GRB_name GRB081221A
GCN_number 8711
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 8711 SUBJECT: GRB 081221: Probable host galaxy in Keck imaging DATE: 08/12/23 11:23:47 GMT FROM: Daniel Perley at U.C. Berkeley D. A. Perley, J. S. Bloom (UC Berkeley), J. Kalirai (STSCI), R. Strickler, E. Ramirez-Ruiz (UCSC), and A. A. Miller (UCB) report: We began a series of deep optical imaging exposures on the field of GRB 081221 (Hoversten et al., GCN 8687) using the Keck I telescope (+LRIS) starting at 2008-12-23 at 5:06 UT. We acquired 10x330s in g-band and 10x300s in I-band (simultaneously using the 560 dichroic). A extended source coincident with the Gemini (Tanvir et al., GCN 8698) and Swift XRT (GCN 8690) afterglow positions is clearly detected in our g-band stack, which we tentatively identify as the host galaxy. The magnitude within a 1.0" aperture of this object is approximately B~25.4 (calibrated relative to the USNO star at RA=15.797098, dec=-24.412259, B2=19.59). It is only marginally detected in the I-band imaging, with an estimated magnitude of I~24.5, though photometry in this band is complicated by blending with a nearby object. The detection of a host galaxy would be consistent with a low-redshift origin (GCN 8698). Within the significant uncertainties of the photometric calibration the color of the galaxy appears typical of normal GRB hosts. Further analysis is planned. An image of the field is posted to: http://lyra.berkeley.edu/~dperley/081221/081221hostkeck.png
GCN 8719 table
GRB_name GRB081221A
GCN_number 8719
Detection_method GROND
Circular_text TITLE: GCN CIRCULAR NUMBER: 8719 SUBJECT: GRB 081221: GROND observations DATE: 08/12/23 20:22:43 GMT FROM: Paulo M. J. Afonso at MPE GRB 081221: GROND observations P. Afonso, T. Kruehler, J. Greiner, C. Clemens (all MPE Garching) and A. Updike (Clemson University) report on behalf of the GROND team: GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile) imaged the field of GRB 081221 (Swift trigger 337889, Hoversten et al., GCN #8687) on two epochs simultaneously in g'r'i'z'JHK. This burst was also detected by Konus-Wind (Golenetskii et al. GCN #8694) and the Fermi GBM (Wilson-Hodge, GCN #8704). The first epoch started on 2008-12-22 at 01:33:08 UT roughly 9 hours after the trigger and consisted of 16 images of 375s exposure in g'r'i'z' and 480 images of 10s exposure in JHK. An equal amount of images were obtained during the second epoch in the following night from 01:19:56 UT on, 33 hours after the burst. Inside the refined XRT error circle (Stroh & Hoversten, GCN #8701) we detect in both epochs the object reported by Tanvir et al.(GCN #8698) and Perley et al. (GCN #8711) in g'r'i', but not in z'JHK. No variability between the two epochs is evident, and no other source is detected inside the XRT error circle. Preliminary VEGA magnitudes from the second epoch calibrated against USNO-B field stars and upper limits are as follows: g' = 25.2 +/- 0.3 r' = 24.7 +/- 0.2 i' = 24.4 +/- 0.4 z' > 24.0 J > 21.0 H > 19.8 K > 19.0 Given the large errors due to image statistics, photometric calibration and complicated photometry as pointed out by Perley et al. (GCN #8711), these values are consistent with what is reported in GCNs #8698 and #8711.
GCN 8741 table
GRB_name GRB081221A
GCN_number 8741
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 8741 SUBJECT: VLA radio observation of GRB 081221 DATE: 08/12/27 20:13:00 GMT FROM: Poonam Chandra at U Virginia/NRAO Poonam Chandra (RMC) 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 081221 (GCN 8687) at a frequency of 8.46 GHz on 2008 Dec 27.14 UT. The GRB radio afterglow is undetected at 3-sigma level. However, there is a 2.5 sigma source (97 +/- 38 uJy) at the Gemini optical afterglow position reported by Tanvir et al. (GCN 8698). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc."
GCN 8748 table
GRB_name GRB081221A
GCN_number 8748
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 8748 SUBJECT: VLA radio detection of GRB 081221 DATE: 08/12/28 16:10:17 GMT FROM: Poonam Chandra at U Virginia/NRAO Poonam Chandra (RMC) and Dale A. Frail (NRAO) report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration: "We used the Very Large Array to re-observe the field of view toward GRB 081221 (GCN 8687) at a frequency of 8.46 GHz on 2008 Dec 28.16 UT for a longer integration. The GRB radio afterglow is clearly detected at the Gemini optical afterglow position (GCN 8698) with the flux density of 167 +/- 27 uJy. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc."