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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"

28300 results found.

  1. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  2. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  3. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  4. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  5. EP250711a: CrAO and Assy optical observations
  6. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  7. EP250730a: COLIBRÍ optical upper limit
  8. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  9. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  10. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  11. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  12. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  13. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  14. GRB 250727A: EP-FXT follow-up observation
  15. GRB 250725A: PRIME near-infrared observations
  16. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  17. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  18. GRB 250728A: Swift-XRT observations
  19. GRB 250728A: COLIBRÍ optical upper limit
  20. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  21. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  22. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  23. GRB 250727A: EP-FXT counterpart detection
  24. GRB 250727A: Swift-XRT observations
  25. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  26. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  27. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  28. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  29. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  30. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  31. GRB 250725A: Swift-XRT refined Analysis
  32. GRB 250725A: Fermi GBM Observation
  33. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  34. GRB 250725A: Swift-BAT refined analysis
  35. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  36. GRB 250725A: SVOM/GRM observation
  37. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  38. GRB 250725A: Swift/UVOT Upper Limits
  39. GRB 250725A: Fermi-LAT detection
  40. GRB 250725A: BOOTES-7 early optical detection
  41. GRB 250725A: SVOM/VT optical candidate
  42. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  43. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  44. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  45. GRB 250725A: Enhanced Swift-XRT position
  46. GRB 250725A: Swift detection of a burst
  47. Swift GRB 250725A: Global MASTER-Net OT detection
  48. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  49. SVOM J195836+32283 is not a real source
  50. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  51. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  52. GRB 250721A: Fermi GBM Observation
  53. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  54. GRB 250721A: Swift-XRT observations
  55. GRB 250717B: SVOM/GRM observation
  56. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  57. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  58. GRB 250721A: MAXI/GSC detection
  59. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  60. GRB 250717B: COLIBRÍ optical upper limit
  61. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  62. GRB 250717B: Swift-XRT observations
  63. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  64. Swift GRB250718.01: Global MASTER-Net observations report
  65. GRB 270713A: Kitab and AbAO Optical Observations
  66. GRB 250717B: Fermi GBM Observation
  67. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  68. GRB 250716A: Swift-XRT afterglow detection
  69. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  70. GRB 250716A: Fermi GBM Observation
  71. GRB 250714A: SVOM/GRM observation
  72. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  73. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  74. GRB 250713A: Mephisto optical upper limits
  75. GRB 250713A: SVOM/VT optical upper limit
  76. GRB 250713A: NOT optical upper limits
  77. GRB 250713A: OHP/T193 upper limit
  78. GRB 250713A: SVOM/C-GFT upper limit
  79. GRB 250706B/C: 7DT Follow-up Observations
  80. GRB 250713A: Swift-XRT observations
  81. GRB 250713A: EP-FXT counterpart detection
  82. EP250711a: COLIBRÍ continuous optical observations
  83. GRB 250706A: Swift-BAT refined analysis
  84. GRB 250702F: Swift-BAT refined analysis
  85. GRB 250628A: Swift-BAT refined analysis
  86. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  87. GRB 250713A: JinShan optical upper limits
  88. GRB 250713A: SVOM detection of a long burst
  89. EP250711a: Global MASTER-Net observations report
  90. GRB 250711A: DDOTI Optical Upper Limit
  91. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  92. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  93. GRB 250711A: SVOM/GRM observation
  94. EP250711a: NOT optical counterpart candidate
  95. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  96. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  97. GRB 250704A: GRANDMA observations
  98. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  99. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  100. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO

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