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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').
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"

18512 results found.

  1. GRB 250812A: EP-FXT counterpart detection
  2. EP 250812a: GOTO optical upper limit
  3. GRB 250812A: Kilonova-Catcher optical afterglow detection
  4. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  5. EP250812a: Einstein Probe detection of an X-ray transient
  6. GRB 250812A: Swift-XRT afterglow detection
  7. GRB 250812A: TRT likely optical counterpart detection
  8. GRB 250809A: Swift/UVOT Detection
  9. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  10. GRB 250809A: Swift-XRT refined Analysis
  11. EP250807a: EP-FXT follow-up observation upper limit
  12. GRB 250809A: LCOGT Optical Upper Limits
  13. GRB 250808A: VLT X-shooter candidate counterpart
  14. GRB 250809A: Swift detection of a gamma ray burst
  15. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  16. GRB 250808A: Fermi GBM Observation
  17. GRB 250807B: Swift/UVOT Detection
  18. GRB 250807B: Kilonova-Catcher optical afterglow detection
  19. GRB 250807A: Swift/UVOT Detection
  20. EP250807a: NTT z-band optical upper limit
  21. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  22. GRB 250807A: SVOM/GRM observation
  23. GRB 250807B: Swift-XRT refined Analysis
  24. EP250807a: EP-WXT detection of a fast X-ray transient
  25. EP 250807.979: GOTO optical upper limit
  26. EP250807a: COLIBRÍ optical upper limit
  27. GRB 250807B: Enhanced Swift-XRT position
  28. GRB 250807A: Enhanced Swift-XRT position
  29. GRB 250807B: Swift detection of a burst with an optical counterpart.
  30. GRB 250805A: Kilonova-Catcher optical upper limits
  31. GRB 250805A: Swift/UVOT Upper Limits
  32. GRB 250806A: Swift/UVOT U-band detection
  33. EP250806a: Liverpool telescope optical upper limit
  34. GRB 250807A: Swift detection of a burst with an optical counterpart
  35. GRB 250806A: EP-FXT observation
  36. EP250802a: EP-FXT follow-up observation
  37. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  38. EP250806a: SVOM /VT optical candidate
  39. GRB 250806A: J-band upper limit from WINTER
  40. GRB 250806A: KAIT optical upper limit
  41. GRB 250806A: SVOM/VT refined analysis
  42. EP250806a: COLIBRÍ optical upper limit
  43. GRB 250806A: Kilonova-Catcher optical upper limits
  44. EP250806a: Einstein Probe detection of an X-ray transient
  45. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  46. GRB 250806A: SVOM/VT optical upper limit
  47. GRB 250806A: SVOM detection of a soft burst
  48. GRB 250805A: SVOM/VT optical counterpart
  49. GRB 250805A: Enhanced Swift-XRT position
  50. GRB 250804C: AstroSat CZTI detection of a long burst
  51. GRB 250805A: TRT optical upper limits
  52. GRB 250805A: Swift-XRT observations
  53. GRB 250804B: SVOM/GRM observation of a short burst
  54. EP250802a: additional Liverpool Telescope upper limits
  55. EP250730a: SVOM/VT optical upper limit
  56. EP250802a: Liverpool Telescope optical upper limits
  57. EP250802a: GROWTH-India Telescope optical upper limit
  58. EP250802a: Einstein Probe detection of an X-ray transient
  59. The EP-WXT trigger 01709198251 is likely a flaring star
  60. The EP-WXT trigger 01709198202 is likely a flaring star
  61. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  62. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  63. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  64. EP250711a: CrAO and Assy optical observations
  65. EP250730a: COLIBRÍ optical upper limit
  66. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  67. EP250730a: Einstein Probe detection of an X-ray transient
  68. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  69. GRB 250725A: AstroSat CZTI detection
  70. GRB 250727A: EP-FXT follow-up observation
  71. GRB 250725A: PRIME near-infrared observations
  72. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  73. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  74. GRB 250728A: COLIBRÍ optical upper limit
  75. GRB 250727A: AST3-2 Upper limit
  76. GRB 250727A: EP-FXT counterpart detection
  77. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  78. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  79. The EP-WXT trigger 01709195487 is likely a flaring star
  80. Konus-Wind detection of GRB 250725A
  81. GRB 250725A: SVOM/GRM observation
  82. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  83. GRB 250725A: Swift/UVOT Upper Limits
  84. GRB 250725A: SVOM/VT optical candidate
  85. GRB 250725A: Enhanced Swift-XRT position
  86. GRB 250725A: Swift detection of a burst
  87. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  88. SVOM J195836+32283 is not a real source
  89. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  90. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  91. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  92. GRB 250721A: Swift-XRT observations
  93. GRB 250717B: SVOM/GRM observation
  94. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  95. GRB 250717B: COLIBRÍ optical upper limit
  96. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  97. GRB 270713A: Kitab and AbAO Optical Observations
  98. GRB 250716A: Swift-XRT afterglow detection
  99. GRB 250714A: SVOM/GRM observation
  100. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations

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