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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

27039 results found.

  1. Swift Trigger 1404295 is not a GRB
  2. GRB 251017A: COLIBRÍ Early Afterglow Detection
  3. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  4. GRB 251017A: Swift detection of a burst with an optical counterpart
  5. GRB 251016A: CALET Gamma-Ray Burst Monitor detection
  6. GRB 251016B: CALET Gamma-Ray Burst Monitor detection
  7. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  8. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  9. GRB 251007B: Swift-BAT refined analysis
  10. GRB 251016B: Fermi GBM Final Real-time Localization
  11. GRB 251014D: Swift-BAT refined analysis
  12. GRB 251016A: BOOTES-6/DPRT optical upper limit
  13. GRB 251016A: Glowbug gamma-ray detection of a short burst
  14. sb25101602: Swift-XRT counterpart detection
  15. Fermi GRB 251016A: Global MASTER-Net observations report
  16. GRB 251016A: Fermi GBM Final Localization
  17. GRB 251016A: SVOM detection of a short burst
  18. GRB 251014B: PRIME J-band upper limit
  19. IceCube Alert 251014.77: Global MASTER-Net observations report
  20. Swift GRB251015.60: Global MASTER-Net observations report
  21. GRB 251013C: Kilonova-Catcher optical afterglow detection
  22. GRB 251013D: Swift/UVOT Observations
  23. GRB 251013C: Swift/UVOT Detection
  24. Fermi Gamma-ray Burst Monitor trigger 782237334/251015673 is not a GRB
  25. GRB 251015A: Fermi GBM Final Real-time Localization
  26. GRB 251013C: SVOM/ECLAIRs refined analysis
  27. Swift Trigger 1404295: possible GRB 251015A
  28. GRB 251014B: Swift/UVOT Upper Limits
  29. GRB 251014B: VLT/FORS2 Optical Observation
  30. GRB 251014D: Swift/UVOT Upper Limits
  31. GRB 251014D: BOOTES-6/DPRT optical upper limit
  32. GRB 251011B: SVOM/VT optical upper limit
  33. GRB 251013D: Fermi GBM Observation
  34. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
  35. GRB 251014A: Swift-BAT refined analysis
  36. GRB 251014D: Swift detection of a burst
  37. GRB 251014C: Fermi GBM Final Localization
  38. GRB 251014A: VLT/FORS2 Optical Observation
  39. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  40. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  41. GRB 251013C: Bassano Bresciano Observatory optical observations
  42. GRB 251013C: Early and late-time optical counterpart detection by LCO
  43. GRB 251013C: Fermi GBM Observation
  44. GRB 251014A: DDOTI Upper Limit
  45. GRB 251013C NUTTelA-TAO / BSTI Early Measurements
  46. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  47. GRB 251013A: CALET Gamma-Ray Burst Monitor detection
  48. GRB 251013C: ABObservatory optical observations
  49. GRB 251014A: Fermi GBM Observation
  50. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  51. GRB 251013C: EP-FXT counterpart detection
  52. GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst
  53. GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
  54. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) detection of the optical counterpart
  55. GRB 251013C: DDOTI detection of the optical afterglow
  56. GRB 251013C: SLKT optical afterglow photometry
  57. Swift GRB 251014A: Global MASTER-Net observations report
  58. GRB 251014A: Swift detection of a possibly-short burst
  59. GRB 251014A: Fermi GBM Final Real-time Localization
  60. Fermi trigger No 782044789: Global MASTER-Net observations report
  61. Fermi GRB 251013C: Global MASTER-Net observations report
  62. Fermi GRB 251013B: Global MASTER-Net observations report
  63. Fermi GRB 251013D: Global MASTER-Net observations report
  64. GRB 251013C: Swift-XRT counterpart detection
  65. GRB 251013C: GOTO optical afterglow detection
  66. GRB 251013D: Fermi GBM Final Real-time Localization
  67. GRB 251013C: SVOM/VT optical observation
  68. GRB 251013C: SVOM detection of a burst
  69. GRB 251013C: Fermi GBM Final Real-time Localization
  70. GRB 251013B: SVOM/GRM observation
  71. GRB 251013A: SVOM/GRM observation
  72. GRB 251003A: Mondy optical upper limit
  73. MASTER OT J011025.98-583210.6 : SVOM/VT optical observation
  74. GRB 251013B: Fermi GBM Final Real-time Localization
  75. Fermi GRB 251013A: Global MASTER-Net observations report
  76. GRB 251013A: Fermi GBM Final Real-time Localization
  77. GRB 251011B: Swift/UVOT Upper Limits
  78. Fermi GRB 251011A: Global MASTER-Net observations report
  79. GRB 251012A: Fermi GBM Final Real-time Localization
  80. GRB 251011B: SVOM/GRM observation
  81. GRB 251011B: Swift-XRT refined Analysis
  82. GRB 251011B: Fermi GBM Observation
  83. GRB 251011C: Fermi GBM Final Real-time Localization
  84. GRB 251009B: SVOM/GRM observation of short GRB
  85. GRB 251011B: Swift detection of a burst
  86. GRB 251011B: Fermi GBM Final Real-time Localization
  87. GRB 251011A: Fermi GBM Final Real-time Localization
  88. Fermi Gamma-ray Burst Monitor trigger 781824269/251010892 is not a GRB
  89. GRB 251007B: Swift/UVOT Upper Limits
  90. GRB 251010A: Fermi GBM Final Real-time Localization
  91. GRB251007A: Swift/UVOT Detection
  92. GRB 251009A: GECAM-B detection of a short burst
  93. GRB 251007A: Swift-BAT refined analysis
  94. GRB 251009A: SVOM/GRM observation of short GRB with possible tail emission
  95. GRB 251007A: SVOM/GRM observation
  96. GRB 251006A: CALET Gamma-Ray Burst Monitor detection
  97. GRB 251007B - SVOM/ECLAIRs refined analysis
  98. SVOM/sb25101004: SVOM detection of a stellar flare
  99. GRB 251009A: Fermi GBM Final Localization
  100. GRB 251006A: Fermi GBM Observation

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