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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"

18503 results found.

  1. GRB 250809A: Swift-XRT refined Analysis
  2. EP250807a: EP-FXT follow-up observation upper limit
  3. GRB 250809A: LCOGT Optical Upper Limits
  4. GRB 250808A: VLT X-shooter candidate counterpart
  5. GRB 250809A: Swift detection of a gamma ray burst
  6. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  7. GRB 250808A: Fermi GBM Observation
  8. GRB 250807B: Swift/UVOT Detection
  9. GRB 250807B: Kilonova-Catcher optical afterglow detection
  10. GRB 250807A: Swift/UVOT Detection
  11. EP250807a: NTT z-band optical upper limit
  12. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  13. GRB 250807A: SVOM/GRM observation
  14. GRB 250807B: Swift-XRT refined Analysis
  15. EP250807a: EP-WXT detection of a fast X-ray transient
  16. EP 250807.979: GOTO optical upper limit
  17. EP250807a: COLIBRÍ optical upper limit
  18. GRB 250807B: Enhanced Swift-XRT position
  19. GRB 250807A: Enhanced Swift-XRT position
  20. GRB 250807B: Swift detection of a burst with an optical counterpart.
  21. GRB 250805A: Kilonova-Catcher optical upper limits
  22. GRB 250805A: Swift/UVOT Upper Limits
  23. GRB 250806A: Swift/UVOT U-band detection
  24. EP250806a: Liverpool telescope optical upper limit
  25. GRB 250807A: Swift detection of a burst with an optical counterpart
  26. GRB 250806A: EP-FXT observation
  27. EP250802a: EP-FXT follow-up observation
  28. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  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. EP250806a: COLIBRÍ optical upper limit
  34. GRB 250806A: Kilonova-Catcher optical upper limits
  35. EP250806a: Einstein Probe detection of an X-ray transient
  36. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  37. GRB 250806A: SVOM/VT optical upper limit
  38. GRB 250806A: SVOM detection of a soft burst
  39. GRB 250805A: SVOM/VT optical counterpart
  40. GRB 250805A: Enhanced Swift-XRT position
  41. GRB 250804C: AstroSat CZTI detection of a long burst
  42. GRB 250805A: TRT optical upper limits
  43. GRB 250805A: Swift-XRT observations
  44. GRB 250804B: SVOM/GRM observation of a short burst
  45. EP250802a: additional Liverpool Telescope upper limits
  46. EP250730a: SVOM/VT optical upper limit
  47. EP250802a: Liverpool Telescope optical upper limits
  48. EP250802a: GROWTH-India Telescope optical upper limit
  49. EP250802a: Einstein Probe detection of an X-ray transient
  50. The EP-WXT trigger 01709198251 is likely a flaring star
  51. The EP-WXT trigger 01709198202 is likely a flaring star
  52. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  53. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  54. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  55. EP250711a: CrAO and Assy optical observations
  56. EP250730a: COLIBRÍ optical upper limit
  57. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  58. EP250730a: Einstein Probe detection of an X-ray transient
  59. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  60. GRB 250725A: AstroSat CZTI detection
  61. GRB 250727A: EP-FXT follow-up observation
  62. GRB 250725A: PRIME near-infrared observations
  63. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  64. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  65. GRB 250728A: COLIBRÍ optical upper limit
  66. GRB 250727A: AST3-2 Upper limit
  67. GRB 250727A: EP-FXT counterpart detection
  68. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  69. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  70. The EP-WXT trigger 01709195487 is likely a flaring star
  71. Konus-Wind detection of GRB 250725A
  72. GRB 250725A: SVOM/GRM observation
  73. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  74. GRB 250725A: Swift/UVOT Upper Limits
  75. GRB 250725A: SVOM/VT optical candidate
  76. GRB 250725A: Enhanced Swift-XRT position
  77. GRB 250725A: Swift detection of a burst
  78. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  79. SVOM J195836+32283 is not a real source
  80. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  81. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  82. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  83. GRB 250721A: Swift-XRT observations
  84. GRB 250717B: SVOM/GRM observation
  85. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  86. GRB 250717B: COLIBRÍ optical upper limit
  87. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  88. GRB 270713A: Kitab and AbAO Optical Observations
  89. GRB 250716A: Swift-XRT afterglow detection
  90. GRB 250714A: SVOM/GRM observation
  91. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  92. GRB 250713A: Mephisto optical upper limits
  93. GRB 250713A: SVOM/VT optical upper limit
  94. GRB 250713A: NOT optical upper limits
  95. GRB 250713A: OHP/T193 upper limit
  96. GRB 250713A: SVOM/C-GFT upper limit
  97. GRB 250706B/C: 7DT Follow-up Observations
  98. GRB 250713A: EP-FXT counterpart detection
  99. EP250711a: COLIBRÍ continuous optical observations
  100. GRB 250628A: Swift-BAT refined analysis

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