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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

28248 results found.

  1. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  2. LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate
  3. GRB 251113A: Glowbug gamma-ray detection
  4. GRB 251112A: Swift-BAT refined analysis
  5. Fermi trigger No 784717756: Global MASTER-Net observations report
  6. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  7. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  8. Fermi GRB 251114A: Global MASTER-Net observations report
  9. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  10. Fermi GRB 251113A: Global MASTER-Net observations report
  11. GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
  12. GRB 251112A: Swift/UVOT Upper Limits
  13. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  14. GRB 251112A: Swift-XRT refined Analysis
  15. GRB 251112B: MAXI/GSC detection
  16. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  17. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  18. GRB 251108B: Glowbug gamma-ray detection
  19. Swift Trigger 1413695: a possible GRB 251112A
  20. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  21. Fermi trigger No 784621743: Global MASTER-Net observations report
  22. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  23. GRB251111A: 1.3m DFOT optical upper limit
  24. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  25. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  26. GRB 251111A: Swift-XRT afterglow detection
  27. GRB 251111A: SVOM/VT optical observations with X-band data
  28. SVOM GRB251111.42: Global MASTER-Net observations report
  29. GRB 251111A: Swift-XRT observations
  30. SVOM GRB251111.22: Global MASTER-Net observations report
  31. GRB 251111A: EP-FXT counterpart detection
  32. GRB 251013C: Chandra X-ray observations and jet break detection
  33. GRB 251111A: SVOM/VT optical observations with VHF data
  34. GRB 251111A: LCO optical observation
  35. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  36. GRB 251103B: Swift-BAT refined analysis
  37. GRB 251106A: Swift/UVOT Upper Limits
  38. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  39. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  40. IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube
  41. LIGO/Virgo/KAGRA S251108fi: Updated Sky localization
  42. LIGO/Virgo/KAGRA S251108dn: Updated Sky localization
  43. Fermi trigger No 784329591: Global MASTER-Net observations report
  44. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  45. Fermi trigger No 784279167: Global MASTER-Net observations report
  46. SVOM GRB251108.54: Global MASTER-Net observations report
  47. GRB 251102B: SVOM/GRM observation
  48. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  49. SVOM GRB251106.83: Global MASTER-Net observations report
  50. LIGO/Virgo/KAGRA S251105aj: Updated Sky localization
  51. LIGO/Virgo/KAGRA S251103f: Updated Sky localization
  52. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  53. GRB 251106A: Swift-XRT afterglow detection
  54. GRB 251106A: Kilonova-Catcher optical upper limit
  55. Fermi GBM Sub-Threshold Detection of GRB 251106A
  56. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  57. GRB 251106A: MASTER optical observations
  58. GRB 251025C: TERI Gamma-ray detection
  59. GRB 251016B: TERI Gamma-ray detection
  60. GRB 251016A: TERI Gamma-ray detection of a short burst
  61. GRB 250920C: TERI Gamma-ray detection
  62. Fermi trigger No 784034269: Global MASTER-Net observations report
  63. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  64. GRB 251105A: Fermi GBM Observation
  65. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  66. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  67. Fermi GBM Sub-Threshold Detection of GRB 251105B
  68. GRB 251103B: Swift/UVOT Upper Limits
  69. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  70. GRB 251103B: Fermi GBM observation
  71. GRB 251103A: WFST optical observations
  72. GRB 251103A: OHP/T193 optical observations
  73. GRB 251103A: Xinglong 2.16m optical detection
  74. GRB 251103A: KAIT optical observations
  75. GRB 251103B: Nanshan/HMT optical upper limit
  76. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  77. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  78. GRB 251103B: MITSuME Akeno optical upper limits
  79. GRB 251103B: Swift-XRT refined Analysis
  80. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  81. EP251102a: NIR observations with WINTER
  82. GRB 251103A: J-band detection with WINTER
  83. GRB 251103B: GROWTH-India Telescope optical upper limits
  84. GRB 251103A: Kilonova-Catcher optical afterglow detection
  85. GRB 251103B: Enhanced Swift-XRT position
  86. GRB 251103B: Swift detection of a burst
  87. GRB 251103A: Swift/UVOT Detection
  88. GRB 251103A: Fermi GBM Observation
  89. GRB 251103A: Swift-XRT afterglow detection
  90. LIGO/Virgo/KAGRA S251031cq: Updated Sky localization
  91. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  92. EP251102a: Einstein Probe detection of a fast X-ray transient
  93. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  94. GRB 251103A: LCO optical observation
  95. EP251102.890: COLIBRÍ optical counterpart candidate
  96. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  97. GRB 251103A: LCO optical afterglow detection
  98. GRB 251103A: NOT optical afterglow candidate
  99. GRB 251031A: Fermi GBM Observation
  100. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate

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