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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"

36195 results found.

  1. GRB 250806A: J-band upper limit from WINTER
  2. GRB 250805A: Swift-BAT refined analysis
  3. GRB 250806A: KAIT optical upper limit
  4. GRB 250806A: SVOM/VT refined analysis
  5. GRB 250806A: Swift-XRT counterpart detection
  6. GRB 250806A: Kilonova-Catcher optical upper limits
  7. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  8. GRB 250806A: SVOM/VT optical upper limit
  9. GRB 250806A: SVOM detection of a soft burst
  10. GRB 250805A: SVOM/VT optical counterpart
  11. GRB 250805A: ESO/VLT observations
  12. GRB 250805A: Swift-XRT refined Analysis
  13. GRB 250804B: Swift-XRT observations
  14. GRB 250805A: Enhanced Swift-XRT position
  15. GRB 250804C: AstroSat CZTI detection of a long burst
  16. GRB 250805A: TRT optical upper limits
  17. GRB 250805A: Swift-XRT observations
  18. GRB 250805A: Swift detection of a burst
  19. GRB 250804B: Tiled Swift observations
  20. GRB 250804B: SVOM/GRM observation of a short burst
  21. GRB 250804A: Fermi GBM Final Localization
  22. Fermi Gamma-ray Burst Monitor trigger 775945985/250803856 is not a GRB
  23. GRB 250702B: SMA observations
  24. EP250711a: CrAO and Assy optical observations
  25. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  26. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  27. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  28. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  29. GRB 250725A: AstroSat CZTI detection
  30. GRB 250727A: EP-FXT follow-up observation
  31. GRB 250725A: PRIME near-infrared observations
  32. GRB: Clarification on Gamma-Ray Burst Naming Convention
  33. GRB 250728A: Swift-XRT observations
  34. GRB 250727A: SVOM/ECLAIRs refined analysis
  35. GRB 250728A: COLIBRÍ optical upper limit
  36. GRB 250728A: Fermi GBM Observation
  37. GRB 250728A: Swift ToO observations
  38. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  39. GRB 250727A: AST3-2 Upper limit
  40. GRB 250727A: EP-FXT counterpart detection
  41. GRB250727A: SVOM/VT optical upper limit
  42. GRB 250727A: Swift-XRT observations
  43. GRB 250727A: SVOM detection of a burst
  44. GRB 250725A: Swift-XRT refined Analysis
  45. GRB 250725A: Fermi GBM Observation
  46. GRB 250725A: Swift-BAT refined analysis
  47. Konus-Wind detection of GRB 250725A
  48. GRB 250725A: SVOM/GRM observation
  49. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  50. GRB 250725A: Swift/UVOT Upper Limits
  51. GRB 250725A: Fermi-LAT detection
  52. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  53. GRB 250725A: BOOTES-7 early optical detection
  54. GRB 250725A: SVOM/VT optical candidate
  55. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  56. GRB 250725A: Enhanced Swift-XRT position
  57. GRB 250725A: Swift detection of a burst
  58. Swift GRB 250725A: Global MASTER-Net OT detection
  59. GRB 250725A: Fermi GBM Final Real-time Localization
  60. Fermi GRB 250725A: Global MASTER-Net observations report
  61. Swift GRB 250725A: Global MASTER-Net observations report
  62. GRB 250723B: Fermi GBM Final Real-time Localization
  63. GRB 250721A: Fermi GBM Observation
  64. GRB 250723A: Fermi GBM Final Real-time Localization
  65. Swift-BAT trigger 1334535 is not a GRB
  66. GRB 250721A: Swift-XRT observations
  67. GRB 250722A: Fermi GBM Final Real-time Localization
  68. GRB 250713A : SVOM/ECLAIRs refined analysis
  69. GRB 250717B: SVOM/GRM observation
  70. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  71. GRB 250721A: Tiled Swift observations
  72. GRB 250721A: MAXI/GSC detection
  73. GRB 250721A: Fermi GBM Final Localization
  74. GRB 250720B: Fermi GBM Final Localization Correction
  75. GRB 250720A: Fermi GBM Final Localization
  76. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  77. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  78. GRB 250717B: COLIBRÍ optical upper limit
  79. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  80. GRB 250717B: Swift-XRT observations
  81. GRB 250718B: Fermi GBM Final Localization Correction
  82. GRB 250718B: Fermi GBM Final Real-time Localization
  83. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  84. Swift Trigger 1334535: a possible GRB 250718A
  85. GRB 250717B: Swift ToO observations
  86. GRB 270713A: Kitab and AbAO Optical Observations
  87. GRB 250717B: Fermi GBM Observation
  88. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  89. Konus-Wind detection of GRB 250716A
  90. GRB 250716A: Swift-XRT afterglow detection
  91. GRB 250717B: Fermi GBM Final Real-time Localization
  92. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  93. GRB 250717A: Fermi GBM Final Real-time Localization
  94. GRB 250716A: Swift ToO observations
  95. GRB 250716A: GOTO tentative optical counterpart candidate
  96. GRB 250716A: Fermi GBM Observation
  97. GRB 250714A: SVOM/GRM observation
  98. Fermi GRB 250716A: Global MASTER-Net observations report
  99. GRB 250716A: Fermi GBM Final Real-time Localization
  100. Fermi GRB 250715A: Global MASTER-Net observations report

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