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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"

2410 results found.

  1. EP250812a: SVOM/VT optical counterpart
  2. GRB 250812A: EP-FXT counterpart detection
  3. GRB 250812A: Swift ToO observations
  4. GRB 250812A: Kilonova-Catcher optical afterglow detection
  5. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  6. GRB 250812A: SVOM/VT optical afterglow confirmation
  7. GRB 250812A: TRT likely optical counterpart detection
  8. GRB 250812A: SVOM detection of a faint long burst
  9. GRB 250807B: SVOM/VT optical observation
  10. GRB 250808A: VLT X-shooter candidate counterpart
  11. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  12. GRB 250808A: Fermi GBM Observation
  13. GRB 250808A: Swift-XRT candidate counterpart detection
  14. GRB 250807A: SVOM/VT optical continued observation
  15. GRB 250808A: SVOM detection of a long burst
  16. Konus-Wind detection of GRB 250807A
  17. GRB 250806A: SVOM/MXT refined analysis
  18. GRB 250806A: SVOM/ECLAIRs refined analysis
  19. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  20. GRB 250804B: Insight-HXMT detection
  21. GRB 250807A: SVOM/GRM observation
  22. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  23. GRB 250807A: SVOM/VT optical observation
  24. GRB 250805A: Kilonova-Catcher optical upper limits
  25. EP250806a:SVOM/VT refined analysis
  26. GRB 250806A: Swift/UVOT U-band detection
  27. EP250806a: Liverpool telescope optical upper limit
  28. GRB 250806A: EP-FXT observation
  29. EP250806a: SVOM /VT optical candidate
  30. GRB 250806A: J-band upper limit from WINTER
  31. GRB 250806A: KAIT optical upper limit
  32. GRB 250806A: SVOM/VT refined analysis
  33. GRB 250806A: Swift-XRT counterpart detection
  34. GRB 250806A: Kilonova-Catcher optical upper limits
  35. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  36. GRB 250806A: SVOM/VT optical upper limit
  37. GRB 250806A: SVOM detection of a soft burst
  38. GRB 250805A: SVOM/VT optical counterpart
  39. GRB 250804B: SVOM/GRM observation of a short burst
  40. EP250730a: SVOM/VT optical upper limit
  41. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  42. GRB 250725A: AstroSat CZTI detection
  43. GRB 250727A: EP-FXT follow-up observation
  44. GRB 250727A: SVOM/ECLAIRs refined analysis
  45. GRB 250727A: AST3-2 Upper limit
  46. GRB 250727A: EP-FXT counterpart detection
  47. GRB250727A: SVOM/VT optical upper limit
  48. GRB 250727A: Swift-XRT observations
  49. GRB 250727A: SVOM detection of a burst
  50. Konus-Wind detection of GRB 250725A
  51. GRB 250725A: SVOM/GRM observation
  52. GRB 250725A: Fermi-LAT detection
  53. GRB 250725A: SVOM/VT optical candidate
  54. SVOM J195836+32283 is not a real source
  55. SVOM J195836+32283/sb25072103: Second VT observation
  56. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  57. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  58. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  59. GRB 250713A : SVOM/ECLAIRs refined analysis
  60. GRB 250717B: SVOM/GRM observation
  61. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  62. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  63. GRB 270713A: Kitab and AbAO Optical Observations
  64. GRB 250714A: SVOM/GRM observation
  65. GRB 250713A: Mephisto optical upper limits
  66. GRB 250713A: SVOM/VT optical upper limit
  67. GRB 250713A: NOT optical upper limits
  68. GRB 250713A: SVOM/C-GFT upper limit
  69. GRB 250713A: Swift-XRT observations
  70. GRB 250713A: EP-FXT counterpart detection
  71. GRB 250713A: JinShan optical upper limits
  72. GRB 250713A: SVOM detection of a long burst
  73. GRB 250711A: DDOTI Optical Upper Limit
  74. GRB 250711A: SVOM/GRM observation
  75. GRB 250704A: GRANDMA observations
  76. GRB 250704A: SVOM/ECLAIRs refined analysis
  77. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  78. GRB 250706B/C: Insight-HXMT detection
  79. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  80. EP250704a/GRB250704B : HCT optical and NIR upper limits
  81. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  82. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  83. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  84. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  85. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  86. GRB 250706B/C: Fermi-LAT detection
  87. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  88. GRB 250706B: Swift/UVOT Detection
  89. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  90. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  91. GRB 250706B: refined SVOM/MXT data analysis
  92. GRB 250706B: REM optical observations
  93. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  94. GRB250706B: Swift-XRT counterpart detection
  95. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  96. GRB 250706B: SVOM/VT optical observation
  97. GRB 250706B: TRT bright optical counterpart detection
  98. GRB 250706B: SVOM detection of a long burst
  99. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  100. GRB 250704B: Swift/UVOT Upper Limits

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