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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"

27586 results found.

  1. Fermi GRB 260506A: Global MASTER-Net observations report
  2. GRB 260506A: Fermi GBM Final Real-time Localization
  3. IceCube Alert 260505A: Global MASTER-Net observations report
  4. GRB 260504B: SVOM/VT optical upper limits
  5. GRB 260504C: SVOM/GRM observation of short GRB
  6. GRB 260504B: SVOM/MXT refined analysis and potential detection
  7. GRB 260503A: SVOM/GRM observation of a GRB
  8. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  9. GRB 260504B: REM optical/NIR observations
  10. IPN triangulation of GRB 260429A
  11. GRB 260504B: LCO z-band upper limit
  12. SVOM GRB 260504B: MASTER-OAFA optical observations
  13. GRB 260504B: SVOM detection of a short burst
  14. Fermi GRB 260504A: Global MASTER-Net observations report
  15. GRB 260504A: Fermi GBM Final Real-time Localization
  16. GRB 260503A: Fermi GBM Final Real-time Localization
  17. GRB 260502A: Fermi GBM Final Localization
  18. The EP-WXT trigger 01709261576 is likely a flaring star
  19. GRB 260429B / EP260429a: EP-FXT follow-up observation
  20. EP260502a: BOOTES-7: early optical upper limit
  21. EP260502a: Las Cumbres upper limit
  22. GRB 260429A: SVOM/GRM observation of a short burst
  23. EP260429a: Global MASTER-Net observations report
  24. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  25. EP260429a: LCO optical upper limits
  26. EP260430a: LCO optical upper limits
  27. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  28. GRB 260429A: Fermi GBM Detection
  29. Fermi GRB 260429A: Global MASTER-Net observations report
  30. EP260430a: Global MASTER-Net observations report
  31. EP260430a: Einstein Probe detection of an X-ray transient
  32. GRB 260429A: Fermi GBM Final Real-time Localization
  33. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  34. Fermi GRB 260428A: Global MASTER-Net observations report
  35. GRB 260424B: COLIBRÍ optical upper limit
  36. GRB 260428A: Fermi GBM Final Real-time Localization
  37. GRB 260424C: Fermi GBM Final Localization
  38. GRB 260424B: SVOM/GRM detection of a short burst
  39. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  40. IceCube Alert 260425A: Global MASTER-Net observations report
  41. Fermi trigger No 798737427: Global MASTER-Net observations report
  42. The EP-WXT trigger 01709258652: Mondy optical observations
  43. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  44. GRB 260421B: SVOM/ECLAIRs refined analysis
  45. GRB 260421B: 3.6m DOT optical observation
  46. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  47. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  48. GRB 260421B: SVOM/GRM observation
  49. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  50. GRB 260421B: EP-FXT follow-up observation
  51. The EP-WXT trigger 01709260362 is likely a flaring star
  52. GRB 260421B: J-band upper limit with WINTER
  53. GRB 260421B: LCO optical counterpart detection
  54. GRB 260421B: Fermi GBM Observation
  55. Fermi Gamma-ray Burst Monitor trigger 798482368/260421694 is not a GRB
  56. GRB 260412A: SVOM/ECLAIRs refined analysis
  57. GRB 260421B: SVOM/VT optical observations
  58. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  59. GRB 260310A: Late-time Chandra X-ray Detection
  60. EP260416a: 1.3m DFOT optical observation
  61. Fermi GRB 260421C: Global MASTER-Net observations report
  62. GRB 260421C: Fermi GBM Final Real-time Localization
  63. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  64. Fermi GRB 260421B: Global MASTER-Net observations report
  65. GRB 260421B: LCO optical afterglow confirmation
  66. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  67. GRB 260421B: SVOM detection of a long burst
  68. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)
  69. GRB 260421B: Fermi GBM Final Real-time Localization
  70. Fermi GRB 260421A: Global MASTER-Net observations report
  71. GRB 260421A: Fermi GBM Final Real-time Localization
  72. EP260321a: VLA radio follow-up
  73. GRB 260412A: LCOGT Optical Upper Limits
  74. The EP-WXT trigger 01709260314 is likely a flaring star
  75. EP-WXT trigger 01709260303: KAIT optical observations
  76. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  77. The EP-WXT trigger 01709260303 is likely a flaring star
  78. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  79. GRB 260419B: Fermi GBM Final Real-time Localization
  80. GRB 260419A: Fermi GBM Final Real-time Localization
  81. Fermi trigger No 798275385: Global MASTER-Net observations report
  82. EP260417a: GROWTH-India Telescope optical upper limit
  83. Fermi GRB 260417B: Global MASTER-Net observations report
  84. EP260417b: GROWTH-India Telescope optical upper limit
  85. EP260416a: Ondrejov D50 optical detection
  86. GRB 260418B: Fermi GBM Final Real-time Localization
  87. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  88. EP260417a: Global MASTER-Net observations report
  89. GRB 260418A: Fermi GBM Final Real-time Localization
  90. EP260416a: GMG Optical Observation
  91. Fermi GRB 260417A: Global MASTER-Net observations report
  92. GRB 260417B: Fermi GBM Final Real-time Localization
  93. EP260416a: LCO observations confirm end of flaring phase
  94. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  95. EP260417a: TRT optical counterpart detection
  96. EP-WXT trigger 01709259586: KAIT optical observations
  97. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  98. EP260416a: WFST optical observations and rebrightening
  99. GRB 260417A: Fermi GBM Final Real-time Localization
  100. GOTO26djh/AT2026jpw: SVOM/VT optical observation

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