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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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').
Advanced Search

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"

16195 results found.

  1. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  2. GRB 250704A: GRANDMA observations
  3. GRB 250702B,D,E / EP250702a: ALMA detection
  4. IceCube-250708A: No Candidates from WINTER
  5. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  6. EP250704a/GRB 250704B: 10 GHz VLA detection
  7. The EP-WXT trigger 01709181970 is likely a flaring star
  8. IceCube-250706A: No Candidates from WINTER
  9. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  10. EP250704a/GRB250704B : HCT optical and NIR upper limits
  11. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  12. GRB 250702F: radio detection with the VLA
  13. IceCube-250706A: EP-FXT follow-up observations
  14. GRB 250706B/C: Fermi-LAT detection
  15. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  16. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  17. GRB 250706B: Swift/UVOT Detection
  18. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  19. GRB 250702F: GRANDMA observations
  20. GRB 250706A: Swift/UVOT Upper Limits
  21. GRB 250706B: REM optical observations
  22. GRB 250706A: REM optical/NIR observations
  23. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  24. IceCube-250416A: DDOTI Optical Upper Limit
  25. IceCube-250706A: COLIBRÍ optical upper limits
  26. GRB 250706A: JinShan optical upper limits
  27. GRB 250706A: SAO RAS optical observations
  28. EP250704A: NOWT Detection
  29. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  30. The EP-WXT trigger 01709181580 is likely a flaring star
  31. GRB 250706B: iTelescope optical observations
  32. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  33. GRB 250706B: SVOM/VT optical observation
  34. GRB 250706B: TRT bright optical counterpart detection
  35. GRB 250706A: GROWTH-India Telescope optical upper limit
  36. GRB 250706B: SVOM detection of a long burst
  37. GRB 250706A: Swift detection of a burst
  38. GRB 250704B: Swift-XRT refined Analysis
  39. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  40. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  41. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  42. GRB 250704B: Swift/UVOT Upper Limits
  43. GRB 250704A: Swift/UVOT Detection
  44. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  45. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  46. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  47. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  48. GRB 250702F: Kilonova-Catcher optical afterglow detection
  49. GRB 250702F: Monte Agliale Observatory optical observations
  50. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  51. EP250704a / GRB 250704B: JinShan optical observations
  52. EP250704a / GRB 250704B: SAO RAS optical observations
  53. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  54. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  55. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  56. GRB 250704A: Swift-XRT afterglow detection
  57. EP250704a / GRB 250704B - REM observations
  58. GRB 250702F: GROWTH-India Telescope optical observations
  59. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  60. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  61. EP250702a: WFST optical observations
  62. EP250704a: COLIBRÍ optical counterpart candidate
  63. EP250704a: Einstein Probe detection of an X-ray transient
  64. GRB 250704A: REM detection of the optical afterglow
  65. GRB 250704A: SVOM detection of a burst
  66. GRB 250702F: Swift/UVOT Detection
  67. GRB 250702F: Leavitt Observatory optical observations
  68. GRB 250702F: AKO Optical Afterglow Detection
  69. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  70. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  71. GRB 250702F: Skynet Optical Observations
  72. GRB 250424A: VIRT Optical Upper Limit
  73. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  74. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  75. GRB 250702F: TRT Optical Observation
  76. GRB 250703A: DDOTI Optical Upper Limit
  77. GRB 250702F: REM optical afterglow detection
  78. GRB 250702F: DDOTI Optical Observation
  79. GRB 250702F: COLIBRÍ Observations of the Afterglow
  80. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  81. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  82. GRB 250702F: Enhanced Swift-XRT position
  83. GRB 250702F: NOT observations of the optical afterglow
  84. GRB 250702F: Swift detection of a burst with an optical counterpart
  85. GRB 250702A: Fermi GBM Detection
  86. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  87. GRB 250628B: EP-FXT counterpart detection
  88. GRB 250628A: REM optical/NIR upper limits
  89. GRB 250628A: VLT/X-shooter upper limits
  90. GRB 250628A: Swift/UVOT Upper Limits
  91. GRB 250628A: Enhanced Swift-XRT position
  92. GRB 250628A: Swift detection of a burst
  93. GRB 250625A: Leavitt Observatory afterglow detection
  94. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  95. The EP-WXT trigger 01709179435 is likely a new outburst of the CV SS Cyg
  96. GRB 250625A: SVOM/C-GFT upper limit in early phase
  97. GRB 250625A: Swift/UVOT Upper Limits
  98. GRB 250625A: ABObservatory afterglow detection
  99. GRB 250625A: OHP/T193 optical detection
  100. GRB 250625A: COLIBRÍ optical observations

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