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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').
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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"

19879 results found.

  1. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  2. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  3. EP250704a/GRB250704B : HCT optical and NIR upper limits
  4. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  5. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  6. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  7. GRB 250702F: radio detection with the VLA
  8. IceCube-250706A: EP-FXT follow-up observations
  9. GRB 250706B/C: Fermi-LAT detection
  10. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  11. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  12. GRB 250706B: Swift/UVOT Detection
  13. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  14. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  15. GRB 250702F: GRANDMA observations
  16. GRB 250706A: Swift-XRT refined Analysis
  17. GRB 250706B: refined SVOM/MXT data analysis
  18. GRB 250706A: Swift/UVOT Upper Limits
  19. GRB 250706B: REM optical observations
  20. GRB 250706A: REM optical/NIR observations
  21. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  22. IceCube-250416A: DDOTI Optical Upper Limit
  23. IceCube-250706A: COLIBRÍ optical upper limits
  24. GRB 250706A: JinShan optical upper limits
  25. GRB 250706A: SAO RAS optical observations
  26. EP250704A: NOWT Detection
  27. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  28. GRB 250706B: iTelescope optical observations
  29. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  30. GRB 250706B: SVOM/VT optical observation
  31. GRB 250706B: TRT bright optical counterpart detection
  32. GRB 250706A: GROWTH-India Telescope optical upper limit
  33. GRB 250706B: SVOM detection of a long burst
  34. GRB 250706A: Swift detection of a burst
  35. GRB 250704B: Swift-XRT refined Analysis
  36. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  37. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  38. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  39. GRB 250704B: Swift/UVOT Upper Limits
  40. GRB 250704A: Swift/UVOT Detection
  41. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  42. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  43. Konus-Wind detection of GRB 250703A
  44. IPN triangulation of GRB 250703A
  45. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  46. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  47. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  48. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  49. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  50. GRB 250702F: Kilonova-Catcher optical afterglow detection
  51. GRB 250702F: Monte Agliale Observatory optical observations
  52. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  53. EP250704a / GRB 250704B: JinShan optical observations
  54. EP250704a / GRB 250704B: SAO RAS optical observations
  55. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  56. EP 250704a: BOOTES-5 optical detection
  57. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  58. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  59. GRB 250704A: Swift-XRT afterglow detection
  60. Konus-Wind detection of GRB 250702F
  61. EP250704a / GRB 250704B - REM observations
  62. GRB 250702F: GROWTH-India Telescope optical observations
  63. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  64. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  65. EP250702a: WFST optical observations
  66. EP250704a: COLIBRÍ optical counterpart candidate
  67. EP250704a: Einstein Probe detection of an X-ray transient
  68. GRB 250702F: optical photometry from Konkoly
  69. GRB 250704A: REM detection of the optical afterglow
  70. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  71. GRB 250704A: SVOM detection of a burst
  72. GRB 250702F: Swift/UVOT Detection
  73. GRB 250702F: Leavitt Observatory optical observations
  74. GRB 250702F: AKO Optical Afterglow Detection
  75. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  76. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  77. GRB 250702F: Skynet Optical Observations
  78. GRB 250424A: VIRT Optical Upper Limit
  79. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  80. GRB 250702F: TRT Optical Observation
  81. GRB 250703A: DDOTI Optical Upper Limit
  82. GRB 250702F: REM optical afterglow detection
  83. GRB 250702F: DDOTI Optical Observation
  84. GRB 250702F: COLIBRÍ Observations of the Afterglow
  85. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  86. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  87. GRB 250702F: Enhanced Swift-XRT position
  88. GRB 250702F: NOT observations of the optical afterglow
  89. GRB 250702F: Swift detection of a burst with an optical counterpart
  90. Konus-Wind detection of GRB 250627A
  91. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  92. LIGO/Virgo/KAGRA S250701bq: Identification of a GW compact binary merger candidate
  93. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  94. GRB 250628B: EP-FXT counterpart detection
  95. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  96. LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate
  97. GRB 250628A: REM optical/NIR upper limits
  98. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate
  99. GRB 250628B: SVOM detection of a long burst
  100. GRB 250628A: VLT/X-shooter upper limits

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