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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"
  1. EP260213a: SVOM/VT optical upper limit
  2. EP260213a: Mondy R-band optical upper limit
  3. EP260213a: NUTTelA-TAO Early Optical Limits
  4. EP260213a: SVOM/C-GFT upper limit
  5. EP260213a: refined analysis of the EP-FXT observation
  6. EP260213a: Einstein Probe detection of a fast X-ray transient
  7. EP/WXT 01709258378: NOT optical upper limits
  8. GRB 260212A: SVOM/GRM observation of a long burst
  9. GRB 260213B: Fermi GBM Final Localization
  10. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  11. GRB 260211A - SVOM/ECLAIRs refined analysis
  12. GRB 260204A: SVOM/ECLAIRs refined analysis
  13. GRB 260213A: Fermi GBM Final Localization
  14. GRB 260211A: EP-FXT follow-up observation
  15. GRB 260211A: SVOM/VT optical observation
  16. GRB 260212A: Glowbug gamma-ray detection
  17. GRB 260211A: GOTO optical upper limit
  18. Fermi GRB 260212A: Global MASTER-Net observations report
  19. GRB 260212A: Fermi GBM Final Real-time Localization
  20. GRB 260211A: LAST optical upper limit
  21. GRB 260210A: SVOM/GRM observation
  22. Fermi GBM Sub-Threshold Detection of GRB 260211A
  23. Konus-Wind detection of GRB 260207B
  24. GRB 260128B: SVOM/ECLAIRs refined analysis
  25. GRID detection of GRB 260207B
  26. GRB 260211A: LCO optical upper limits
  27. GRB260131A/B: 3.6m DOT Optical Observations
  28. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  29. Fermi trigger No 792537871: Global MASTER-Net observations report
  30. GRB 260211A: SVOM detection of a burst
  31. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  32. Konus-Wind detection of GRB 260209B
  33. GRB 260208A: Swift UVOT detection
  34. Konus-Wind detection of GRB 260127B
  35. EP260209a: COLIBRÍ optical upper limit
  36. Fermi GRB 260210C: Global MASTER-Net observations report
  37. EP260209a: LCO optical upper limits
  38. EP260210a: Global MASTER-Net observations report
  39. EP260210a: refined analysis of the EP-FXT observation
  40. EP260209a: Global MASTER-Net observations report
  41. GRB 260208A: LCO detection of the optical counterpart
  42. EP260209a: Einstein Probe detection of a fast X-ray transient
  43. EP260210a: Optical upper limits with Kinder observations
  44. IPN triangulation of GRB 260207B (short/hard with EE)
  45. GRB 260210C: Fermi GBM Final Real-time Localization
  46. GRB 260210A: Glowbug gamma-ray detection
  47. GRB 260210B: Fermi GBM Final Real-time Localization
  48. EP260210a: SVOM/VT optical upper limit
  49. GRB 260210A: AstroSat CZTI detection
  50. GRB 260208C: AstroSat CZTI detection
  51. EP260210a: COLIBRÍ optical upper limit
  52. EP260210a: SVOM/C-GFT upper limit
  53. GRB 260208B: refined analysis of the EP-FXT observation
  54. EP260210a: Einstein Probe detection of an X-ray transient
  55. GRB 260207B: AstroSat CZTI detection
  56. GRB 260208C: SVOM/GRM observation
  57. GRB 260204A: Swift-XRT afterglow detection
  58. GRB 260208B: AstroSat CZTI detection of a bright long burst
  59. GRB260208A: Liverpool Telescope optical follow-up observations
  60. GRB 260208A: Glowbug gamma-ray detection
  61. GRB 260208A: NuSTAR detection of prompt emission
  62. GRB 260208A: Fermi GBM Observation
  63. Fermi GRB 260209A: Global MASTER-Net observations report
  64. GRB 260208B: Swift-XRT observations
  65. GRB 260131A/B: continued Mondy optical observations
  66. GRB 260204A: Swift/UVOT Upper Limits
  67. GRB 260208B: COLIBRÍ optical observations
  68. GRB 260208A: Mondy optical observations (duplicate submission)
  69. GRB 260208A: Mondy optical observations
  70. GRB 260208A: 1.3m DFOT optical detection
  71. GRB 260208A: COLIBRÍ optical observations
  72. GRB 260208B: EP-FXT observation
  73. GRB 260208A: NOT spectroscopic redshift z = 2.36
  74. GRB 260208A: Liverpool Telescope optical detection
  75. Fermi GRB 260208C: Global MASTER-Net observations report
  76. GRB 260208B: SVOM/VT optical candidate
  77. GRB 260208A: GECAM-B observation of a bright burst
  78. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  79. GRB 260209A: Fermi GBM Final Real-time Localization
  80. GRB 260208A: SVOM/VT optical observation
  81. Fermi GRB 260208D: Global MASTER-Net observations report
  82. GRB 260208D: Fermi GBM Final Real-time Localization
  83. GRB 260208A: Swift-XRT observations
  84. GRB 260208B: Swift ToO observations
  85. GRB 260208B: SVOM/GRM observation of a bright burst
  86. GRB 260208B: Fermi GBM Detection
  87. LAT GRB 260208B: Global MASTER-Net observations report
  88. GRB 260208B: Fermi-LAT detection
  89. GRB 260208C: Fermi GBM Final Real-time Localization
  90. GRB 260208A: Fermi-LAT detection
  91. GRB 260207B: GECAM-B observation
  92. GRB 260208A: Swift ToO observations
  93. GRB 260208A: Fermi GBM Classification Correction
  94. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  95. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  96. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  97. GRB 260208B: Fermi GBM Final Real-time Localization
  98. Fermi GRB 260208A: Global MASTER-Net observations report
  99. Fermi Gamma-ray Burst Monitor trigger 792220053/260208214 is not a GRB
  100. GRB 260208A: Fermi GBM Final Real-time Localization

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