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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"

36043 results found.

  1. GRB 251013D: Fermi GBM Final Real-time Localization
  2. GRB 251013C: SVOM/VT optical observation
  3. GRB 251013C: SVOM detection of a burst
  4. GRB 251013C: Fermi GBM Final Real-time Localization
  5. GRB 251013B: SVOM/GRM observation
  6. GRB 251013A: SVOM/GRM observation
  7. GRB 251003A: Mondy optical upper limit
  8. GRB 251013B: Fermi GBM Final Real-time Localization
  9. Fermi GRB 251013A: Global MASTER-Net observations report
  10. GRB 251013A: Fermi GBM Final Real-time Localization
  11. GRB 251011B inspection: MASTER orphan GRB detection
  12. GRB 251011A: Insight-HXMT detection
  13. GRB 251011B: Swift/UVOT Upper Limits
  14. Fermi GRB 251011A: Global MASTER-Net observations report
  15. GRB 251012A: Fermi GBM Final Real-time Localization
  16. GRB 251011B: SVOM/GRM observation
  17. GRB 251011B: Swift-XRT refined Analysis
  18. GRB 251011B: Fermi GBM Observation
  19. GRB 251011B : MASTER optical observations
  20. GRB 251011C: Fermi GBM Final Real-time Localization
  21. GRB 251011B: Enhanced Swift-XRT position
  22. GRB 251010A: AstroSat CZTI detection
  23. GRB 251011A: AstroSat CZTI detection
  24. GRB 251009B: SVOM/GRM observation of short GRB
  25. GRB 251011B: Swift detection of a burst
  26. GRB 251011B: Fermi GBM Final Real-time Localization
  27. GRB 251011A: Fermi GBM Final Real-time Localization
  28. Fermi Gamma-ray Burst Monitor trigger 781824269/251010892 is not a GRB
  29. GRB 251007B: Swift/UVOT Upper Limits
  30. GRB 251010A: Fermi GBM Final Real-time Localization
  31. GRB251007A: Swift/UVOT Detection
  32. GRB 251009A: GECAM-B detection of a short burst
  33. GRB 251009A: Insight-HXMT detection of a short burst
  34. GRB 251009B (short): Glowbug gamma-ray detection
  35. GRB 251009B: Insight-HXMT detection of a short burst
  36. GRB 251007A: Swift-BAT refined analysis
  37. GRB 251009A: SVOM/GRM observation of short GRB with possible tail emission
  38. GRB 251007A: SVOM/GRM observation
  39. GRB 251007A: Insight-HXMT detection
  40. GRB 251006A: CALET Gamma-Ray Burst Monitor detection
  41. GRB 251007B - SVOM/ECLAIRs refined analysis
  42. GRB 251009A: Fermi GBM Final Localization
  43. GRB 250916A: TERI Gamma-ray detection
  44. GRB 250919A: TERI gamma-ray detection
  45. GRB 251006A: Fermi GBM Observation
  46. GRB 251007A: 1.5m OSN and 2.2m CAHA optical follow-up
  47. GRB 251002A - SVOM/ECLAIRs refined analysis
  48. GRB 251003A: Fermi GBM Observation
  49. GRB 251006B: Fermi GBM Observation
  50. GRB 251007B: COLIBRÍ optical upper limit
  51. GRB 251007A: AstroSat CZTI detection
  52. GRB 251006B/EP251006a: EP-FXT afterglow detection
  53. GRB 250917B: iTelescope T-26 upper limit
  54. EP250911a: Koshka Zeiss-1000 Optical Upper Limit
  55. GRB 251007B: SVOM/VT optical candidate
  56. GRB 251007A: Swift-XRT refined Analysis
  57. GRB 251007A: Enhanced Swift-XRT position
  58. GRB 251007B: Swift-XRT refined Analysis
  59. GRB 251007B: Enhanced Swift-XRT position
  60. GRB 251007A: NOT optical observations
  61. GRB 251007A: AKO Optical Upper Limit
  62. GRB 251007A: CALET Gamma-Ray Burst Monitor detection
  63. GRB 251006B: Insight-HXMT detection
  64. GRB 251007A: SVOM/C-GFT optical observations
  65. GRB 251005C: PRIME J-band upper limit
  66. Swift GRB 251007B: Global MASTER-Net observations report
  67. GRB 251007A: Glowbug gamma-ray detection
  68. GRB 251007B: SVOM/C-GFT upper limit
  69. Swift GRB 251007A: Global MASTER-Net observations report
  70. GRB 251007B: SVOM detection of a faint burst
  71. GRB 251007B: Swift detection of a burst
  72. GRB 251007A: Swift detection of a burst with an optical counterpart
  73. GRB 250702B/EP250702a: JWST/NIRCam Observations
  74. GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
  75. GRB 251005B: Glowbug gamma-ray detection
  76. GRB 251006B/EP251006a: SVOM/VT optical candidate
  77. GRB 251006B/EP251006a: EP-FXT follow-up observation
  78. GRB 251006B: SVOM/GRM observation
  79. GRB 251006B: COLIBRÍ optical upper limit
  80. GRB 251006B/EP251006a: EP-WXT detection
  81. GRB 251005C: SVOM/VT optical fading
  82. GRB 251005C: SVOM/GRM observation of a likely short GRB
  83. Fermi GRB 251006B: Global MASTER-Net observations report
  84. GRB 251006B: BALROG localization (Fermi Trigger 781473909 / GRB 251006837)
  85. GRB 251006B: Fermi GBM Final Real-time Localization
  86. GRB 251006A (short): Glowbug gamma-ray detection
  87. GRB 251005C: COLIBRÍ optical observations
  88. Fermi GRB 251006A: Global MASTER-Net observations report
  89. GRB 251005C: VLT/X-shooter Imaging
  90. GRB 251003A: LAST optical observations
  91. GRB 251002A: LAST optical observations
  92. GRB 251006A: Fermi GBM Final Real-time Localization
  93. GRB 251005C: SVOM/VT optical candidate
  94. GRB 251005C: AstroSat CZTI detection
  95. GRB 251005C: Swift/UVOT Upper Limits
  96. GRB 250902A: MSU cubesats detection
  97. GRB 251005C: Swift-XRT refined Analysis
  98. GRB 251005C: Fermi GBM Observation
  99. Swift GRB 251005A: Global MASTER-Net observations report
  100. GRB 251005C: Enhanced Swift-XRT position

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