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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"

21799 results found.

  1. Konus-Wind detection of GRB 250807A
  2. GRB 250807B: Swift/UVOT Detection
  3. GRB 250807B: Kilonova-Catcher optical afterglow detection
  4. GRB 250807A: Swift/UVOT Detection
  5. GRB 250807A: Swift-XRT refined Analysis
  6. GRB 250806A: SVOM/MXT refined analysis
  7. EP250807a: NTT z-band optical upper limit
  8. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  9. GRB 250807A: SVOM/GRM observation
  10. GRB 250807A: AstroSat CZTI detection of bright long burst
  11. EP250807a: EP-WXT detection of a fast X-ray transient
  12. EP 250807.979: GOTO optical upper limit
  13. EP250807a: COLIBRÍ optical upper limit
  14. GRB 250807B: Enhanced Swift-XRT position
  15. GRB 250807A: Enhanced Swift-XRT position
  16. GRB 250807B: Swift detection of a burst with an optical counterpart.
  17. GRB 250805A: Kilonova-Catcher optical upper limits
  18. GRB 250805A: Swift/UVOT Upper Limits
  19. GRB 250806A: Swift/UVOT U-band detection
  20. EP250806a: Liverpool telescope optical upper limit
  21. GRB 250807A: Swift detection of a burst with an optical counterpart
  22. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  23. EP250806a: SVOM /VT optical candidate
  24. GRB 250806A: J-band upper limit from WINTER
  25. GRB 250806A: KAIT optical upper limit
  26. GRB 250806A: Swift-XRT counterpart detection
  27. EP250806a: COLIBRÍ optical upper limit
  28. GRB 250806A: Kilonova-Catcher optical upper limits
  29. EP250806a: Einstein Probe detection of an X-ray transient
  30. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  31. GRB 250806A: SVOM/VT optical upper limit
  32. GRB 250806A: SVOM detection of a soft burst
  33. GRB 250805A: SVOM/VT optical counterpart
  34. GRB 250804B: Swift-XRT observations
  35. GRB 250805A: Enhanced Swift-XRT position
  36. GRB 250805A: TRT optical upper limits
  37. GRB 250805A: Swift-XRT observations
  38. GRB 250804B: SVOM/GRM observation of a short burst
  39. EP250802a: additional Liverpool Telescope upper limits
  40. EP250730a: SVOM/VT optical upper limit
  41. EP250802a: Liverpool Telescope optical upper limits
  42. EP250802a: GROWTH-India Telescope optical upper limit
  43. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  44. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  45. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  46. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  47. EP250711a: CrAO and Assy optical observations
  48. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  49. EP250730a: COLIBRÍ optical upper limit
  50. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  51. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  52. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  53. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  54. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  55. GRB 250725A: PRIME near-infrared observations
  56. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  57. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  58. GRB 250727A: SVOM/ECLAIRs refined analysis
  59. GRB 250728A: COLIBRÍ optical upper limit
  60. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  61. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  62. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  63. GRB 250727A: SVOM detection of a burst
  64. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  65. Konus-Wind detection of GRB 250725A
  66. GRB 250725A: SVOM/GRM observation
  67. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  68. GRB 250725A: Swift/UVOT Upper Limits
  69. GRB 250725A: Fermi-LAT detection
  70. GRB 250725A: SVOM/VT optical candidate
  71. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  72. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  73. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  74. GRB 250725A: Enhanced Swift-XRT position
  75. GRB 250725A: Swift detection of a burst
  76. Swift GRB 250725A: Global MASTER-Net OT detection
  77. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  78. SVOM J195836+32283 is not a real source
  79. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  80. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  81. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  82. GRB 250721A: Swift-XRT observations
  83. GRB 250717B: SVOM/GRM observation
  84. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  85. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  86. GRB 250717B: COLIBRÍ optical upper limit
  87. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  88. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  89. GRB 270713A: Kitab and AbAO Optical Observations
  90. GRB 250717B: Fermi GBM Observation
  91. Konus-Wind detection of GRB 250716A
  92. GRB 250716A: Swift-XRT afterglow detection
  93. GRB 250716A: GOTO tentative optical counterpart candidate
  94. GRB 250714A: SVOM/GRM observation
  95. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  96. GRB 250713A: Mephisto optical upper limits
  97. GRB 250713A: SVOM/VT optical upper limit
  98. GRB 250713A: NOT optical upper limits
  99. GRB 250713A: OHP/T193 upper limit
  100. GRB 250713A: SVOM/C-GFT upper limit

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