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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"

35451 results found.

  1. GRB 260213A: GECAM-B observation of a short burst
  2. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  3. GRB 260216A: Fermi GBM Final Real-time Localization
  4. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  5. EP260214a: Optical upper limits with Kinder observations
  6. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  7. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  8. GRB 260211A: SVOM/VT optical counterpart
  9. GRB 260212A: AstroSat CZTI detection
  10. GRB 260212A: Fermi GBM Observation
  11. GRB 260212A: GECAM-B observation
  12. EP260213a: Mondy R-band optical upper limit
  13. GRB 260212A: SVOM/GRM observation of a long burst
  14. GRB 260213B: Fermi GBM Final Localization
  15. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  16. GRB 260211A - SVOM/ECLAIRs refined analysis
  17. GRB 260204A: SVOM/ECLAIRs refined analysis
  18. GRB 260213A: Fermi GBM Final Localization
  19. GRB 260211A: EP-FXT follow-up observation
  20. GRB 260211A: SVOM/VT optical observation
  21. GRB 260212A: Glowbug gamma-ray detection
  22. GRB 260211A: GOTO optical upper limit
  23. Fermi GRB 260212A: Global MASTER-Net observations report
  24. GRB 260212A: Fermi GBM Final Real-time Localization
  25. GRB 260211A: LAST optical upper limit
  26. GRB 260210A: SVOM/GRM observation
  27. Fermi GBM Sub-Threshold Detection of GRB 260211A
  28. Konus-Wind detection of GRB 260207B
  29. GRB 260128B: SVOM/ECLAIRs refined analysis
  30. GRID detection of GRB 260207B
  31. GRB 260211A: LCO optical upper limits
  32. GRB260131A/B: 3.6m DOT Optical Observations
  33. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  34. GRB 260211A: SVOM detection of a burst
  35. Konus-Wind detection of GRB 260209B
  36. GRB 260208A: Swift UVOT detection
  37. Konus-Wind detection of GRB 260127B
  38. Fermi GRB 260210C: Global MASTER-Net observations report
  39. GRB 260208A: LCO detection of the optical counterpart
  40. IPN triangulation of GRB 260207B (short/hard with EE)
  41. GRB 260210C: Fermi GBM Final Real-time Localization
  42. GRB 260210A: Glowbug gamma-ray detection
  43. GRB 260210B: Fermi GBM Final Real-time Localization
  44. GRB 260210A: AstroSat CZTI detection
  45. GRB 260208C: AstroSat CZTI detection
  46. GRB 260208B: refined analysis of the EP-FXT observation
  47. GRB 260207B: AstroSat CZTI detection
  48. GRB 260208C: SVOM/GRM observation
  49. GRB 260204A: Swift-XRT afterglow detection
  50. GRB 260208B: AstroSat CZTI detection of a bright long burst
  51. GRB 260208A: Glowbug gamma-ray detection
  52. GRB 260208A: NuSTAR detection of prompt emission
  53. GRB 260208A: Fermi GBM Observation
  54. Fermi GRB 260209A: Global MASTER-Net observations report
  55. GRB 260208B: Swift-XRT observations
  56. GRB 260131A/B: continued Mondy optical observations
  57. GRB 260204A: Swift/UVOT Upper Limits
  58. GRB 260208B: COLIBRÍ optical observations
  59. GRB 260208A: Mondy optical observations (duplicate submission)
  60. GRB 260208A: Mondy optical observations
  61. GRB 260208A: 1.3m DFOT optical detection
  62. GRB 260208A: COLIBRÍ optical observations
  63. GRB 260208B: EP-FXT observation
  64. GRB 260208A: NOT spectroscopic redshift z = 2.36
  65. GRB 260208A: Liverpool Telescope optical detection
  66. Fermi GRB 260208C: Global MASTER-Net observations report
  67. GRB 260208B: SVOM/VT optical candidate
  68. GRB 260208A: GECAM-B observation of a bright burst
  69. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  70. GRB 260209A: Fermi GBM Final Real-time Localization
  71. GRB 260208A: SVOM/VT optical observation
  72. Fermi GRB 260208D: Global MASTER-Net observations report
  73. GRB 260208D: Fermi GBM Final Real-time Localization
  74. GRB 260208A: Swift-XRT observations
  75. GRB 260208B: Swift ToO observations
  76. GRB 260208B: SVOM/GRM observation of a bright burst
  77. GRB 260208B: Fermi GBM Detection
  78. LAT GRB 260208B: Global MASTER-Net observations report
  79. GRB 260208B: Fermi-LAT detection
  80. GRB 260208C: Fermi GBM Final Real-time Localization
  81. GRB 260208A: Fermi-LAT detection
  82. GRB 260207B: GECAM-B observation
  83. GRB 260208A: Swift ToO observations
  84. GRB 260208A: Fermi GBM Classification Correction
  85. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  86. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  87. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  88. GRB 260208B: Fermi GBM Final Real-time Localization
  89. Fermi GRB 260208A: Global MASTER-Net observations report
  90. Fermi Gamma-ray Burst Monitor trigger 792220053/260208214 is not a GRB
  91. GRB 260208A: Fermi GBM Final Real-time Localization
  92. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  93. GRB 260207A : MASTER optical counterpart discovery
  94. GRB 260131A/B: Mondy and Terskol optical observations
  95. Fermi GRB 260207B: Global MASTER-Net observations report
  96. GRB 260206A: Swift-XRT observations
  97. GRB 260207B: Fermi GBM Final Real-time Localization
  98. GRB 260207A: Fermi GBM Final Localization
  99. EP260131a: VLA detection
  100. GRB 260206A: Tiled Swift observations

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