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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"

37764 results found.

  1. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  2. GRB 250807B: NTT optical observations
  3. GRB 250807A: SVOM/VT optical observation
  4. EP250806a: Upper limit from Fermi-GBM Observations
  5. GRB 250807B: Enhanced Swift-XRT position
  6. GRB 250807A: Enhanced Swift-XRT position
  7. GRB 250807B: Swift detection of a burst with an optical counterpart.
  8. GRB 250805A: Kilonova-Catcher optical upper limits
  9. GRB 250805A: Swift/UVOT Upper Limits
  10. GRB 250806A: Swift/UVOT U-band detection
  11. GRB 250807A: Swift detection of a burst with an optical counterpart
  12. GRB 250806A: EP-FXT observation
  13. GRB 250806A: J-band upper limit from WINTER
  14. GRB 250805A: Swift-BAT refined analysis
  15. GRB 250806A: KAIT optical upper limit
  16. GRB 250806A: SVOM/VT refined analysis
  17. GRB 250806A: Swift-XRT counterpart detection
  18. GRB 250806A: Kilonova-Catcher optical upper limits
  19. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  20. GRB 250806A: SVOM/VT optical upper limit
  21. GRB 250806A: SVOM detection of a soft burst
  22. GRB 250805A: SVOM/VT optical counterpart
  23. GRB 250805A: ESO/VLT observations
  24. GRB 250805A: Swift-XRT refined Analysis
  25. GRB 250804B: Swift-XRT observations
  26. GRB 250805A: Enhanced Swift-XRT position
  27. GRB 250804C: AstroSat CZTI detection of a long burst
  28. GRB 250805A: TRT optical upper limits
  29. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  30. GRB 250805A: Swift-XRT observations
  31. GRB 250805A: Swift detection of a burst
  32. GRB 250804B: Tiled Swift observations
  33. Fermi trigger No 776041355: Global MASTER-Net observations report
  34. GRB 250804B: SVOM/GRM observation of a short burst
  35. GRB 250804A: Fermi GBM Final Localization
  36. Fermi Gamma-ray Burst Monitor trigger 775945985/250803856 is not a GRB
  37. GRB 250702B: SMA observations
  38. EP250711a: CrAO and Assy optical observations
  39. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  40. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  41. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  42. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  43. GRB 250725A: AstroSat CZTI detection
  44. GRB 250727A: EP-FXT follow-up observation
  45. GRB 250725A: PRIME near-infrared observations
  46. GRB: Clarification on Gamma-Ray Burst Naming Convention
  47. GRB 250728A: Swift-XRT observations
  48. GRB 250727A: SVOM/ECLAIRs refined analysis
  49. GRB 250728A: COLIBRÍ optical upper limit
  50. GRB 250728A: Fermi GBM Observation
  51. Fermi trigger No 775387550: Global MASTER-Net observations report
  52. GRB 250728A: Swift ToO observations
  53. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  54. GRB 250727A: AST3-2 Upper limit
  55. GRB 250727A: EP-FXT counterpart detection
  56. GRB250727A: SVOM/VT optical upper limit
  57. GRB 250727A: Swift-XRT observations
  58. GRB 250727A: SVOM detection of a burst
  59. GRB 250725A: Swift-XRT refined Analysis
  60. GRB 250725A: Fermi GBM Observation
  61. GRB 250725A: Swift-BAT refined analysis
  62. Konus-Wind detection of GRB 250725A
  63. GRB 250725A: SVOM/GRM observation
  64. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  65. GRB 250725A: Swift/UVOT Upper Limits
  66. GRB 250725A: Fermi-LAT detection
  67. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  68. GRB 250725A: BOOTES-7 early optical detection
  69. GRB 250725A: SVOM/VT optical candidate
  70. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  71. GRB 250725A: Enhanced Swift-XRT position
  72. GRB 250725A: Swift detection of a burst
  73. Swift GRB 250725A: Global MASTER-Net OT detection
  74. GRB 250725A: Fermi GBM Final Real-time Localization
  75. Fermi GRB 250725A: Global MASTER-Net observations report
  76. Swift GRB 250725A: Global MASTER-Net observations report
  77. GRB 250723B: Fermi GBM Final Real-time Localization
  78. GRB 250721A: Fermi GBM Observation
  79. GRB 250723A: Fermi GBM Final Real-time Localization
  80. Swift-BAT trigger 1334535 is not a GRB
  81. GRB 250721A: Swift-XRT observations
  82. GRB 250722A: Fermi GBM Final Real-time Localization
  83. GRB 250713A : SVOM/ECLAIRs refined analysis
  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 250721A: Tiled Swift observations
  87. GRB 250721A: MAXI/GSC detection
  88. GRB 250721A: Fermi GBM Final Localization
  89. GRB 250720B: Fermi GBM Final Localization Correction
  90. GRB 250720A: Fermi GBM Final Localization
  91. Fermi trigger No 774730635: Global MASTER-Net observations report
  92. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  93. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  94. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  95. GRB 250717B: COLIBRÍ optical upper limit
  96. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  97. GRB 250717B: Swift-XRT observations
  98. GRB 250718B: Fermi GBM Final Localization Correction
  99. GRB 250718B: Fermi GBM Final Real-time Localization
  100. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits

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