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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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

36314 results found.

  1. Fermi Gamma-ray Burst Monitor trigger 775945985/250803856 is not a GRB
  2. GRB 250702B: SMA observations
  3. EP250711a: CrAO and Assy optical observations
  4. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  5. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  6. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  7. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  8. GRB 250725A: AstroSat CZTI detection
  9. GRB 250727A: EP-FXT follow-up observation
  10. GRB 250725A: PRIME near-infrared observations
  11. GRB: Clarification on Gamma-Ray Burst Naming Convention
  12. GRB 250728A: Swift-XRT observations
  13. GRB 250727A: SVOM/ECLAIRs refined analysis
  14. GRB 250728A: COLIBRÍ optical upper limit
  15. GRB 250728A: Fermi GBM Observation
  16. GRB 250728A: Swift ToO observations
  17. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  18. GRB 250727A: AST3-2 Upper limit
  19. GRB 250727A: EP-FXT counterpart detection
  20. GRB250727A: SVOM/VT optical upper limit
  21. GRB 250727A: Swift-XRT observations
  22. GRB 250727A: SVOM detection of a burst
  23. GRB 250725A: Swift-XRT refined Analysis
  24. GRB 250725A: Fermi GBM Observation
  25. GRB 250725A: Swift-BAT refined analysis
  26. Konus-Wind detection of GRB 250725A
  27. GRB 250725A: SVOM/GRM observation
  28. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  29. GRB 250725A: Swift/UVOT Upper Limits
  30. GRB 250725A: Fermi-LAT detection
  31. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  32. GRB 250725A: BOOTES-7 early optical detection
  33. GRB 250725A: SVOM/VT optical candidate
  34. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  35. GRB 250725A: Enhanced Swift-XRT position
  36. GRB 250725A: Swift detection of a burst
  37. Swift GRB 250725A: Global MASTER-Net OT detection
  38. GRB 250725A: Fermi GBM Final Real-time Localization
  39. Fermi GRB 250725A: Global MASTER-Net observations report
  40. Swift GRB 250725A: Global MASTER-Net observations report
  41. GRB 250723B: Fermi GBM Final Real-time Localization
  42. GRB 250721A: Fermi GBM Observation
  43. GRB 250723A: Fermi GBM Final Real-time Localization
  44. Swift-BAT trigger 1334535 is not a GRB
  45. GRB 250721A: Swift-XRT observations
  46. GRB 250722A: Fermi GBM Final Real-time Localization
  47. GRB 250713A : SVOM/ECLAIRs refined analysis
  48. GRB 250717B: SVOM/GRM observation
  49. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  50. GRB 250721A: Tiled Swift observations
  51. GRB 250721A: MAXI/GSC detection
  52. GRB 250721A: Fermi GBM Final Localization
  53. GRB 250720B: Fermi GBM Final Localization Correction
  54. GRB 250720A: Fermi GBM Final Localization
  55. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  56. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  57. GRB 250717B: COLIBRÍ optical upper limit
  58. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  59. GRB 250717B: Swift-XRT observations
  60. GRB 250718B: Fermi GBM Final Localization Correction
  61. GRB 250718B: Fermi GBM Final Real-time Localization
  62. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  63. Swift Trigger 1334535: a possible GRB 250718A
  64. GRB 250717B: Swift ToO observations
  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. Konus-Wind detection of GRB 250716A
  69. GRB 250716A: Swift-XRT afterglow detection
  70. GRB 250717B: Fermi GBM Final Real-time Localization
  71. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  72. GRB 250717A: Fermi GBM Final Real-time Localization
  73. GRB 250716A: Swift ToO observations
  74. GRB 250716A: GOTO tentative optical counterpart candidate
  75. GRB 250716A: Fermi GBM Observation
  76. GRB 250714A: SVOM/GRM observation
  77. Fermi GRB 250716A: Global MASTER-Net observations report
  78. GRB 250716A: Fermi GBM Final Real-time Localization
  79. Fermi GRB 250715A: Global MASTER-Net observations report
  80. GRB 250715A: Fermi GBM Final Real-time Localization
  81. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  82. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  83. GRB 250713A: Mephisto optical upper limits
  84. Fermi GRB 250714A: Global MASTER-Net observations report
  85. GRB 250713A: SVOM/VT optical upper limit
  86. GRB 250713A: NOT optical upper limits
  87. GRB 250713A: OHP/T193 upper limit
  88. GRB 250713A: SVOM/C-GFT upper limit
  89. GRB 250714A: Fermi GBM Final Real-time Localization
  90. GRB 250706B/C: 7DT Follow-up Observations
  91. GRB 250713A: Swift-XRT observations
  92. GRB 250713A: EP-FXT counterpart detection
  93. GRB 250706A: Swift-BAT refined analysis
  94. GRB 250702F: Swift-BAT refined analysis
  95. GRB 250628A: Swift-BAT refined analysis
  96. GRB 250713A: JinShan optical upper limits
  97. GRB 250713A: SVOM detection of a long burst
  98. GRB 250711A: DDOTI Optical Upper Limit
  99. GRB 250711A: SVOM/GRM observation
  100. Fermi GRB 250711A: Global MASTER-Net observations report

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