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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"

28117 results found.

  1. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  2. EP260530a/AT 2026nwl: KAIT optical observations
  3. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  4. EP260602a: Optical upper limits with Kinder observations
  5. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  6. EP260602a: Einstein Probe detection of a fast X-ray transient
  7. GRB 260601B/EP260601a: SVOM/VT optical observations
  8. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  9. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  10. EP260601a: Einstein Probe detection of an X-ray transient
  11. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  12. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  13. GRB 260601A: Glowbug gamma-ray detection of a short burst
  14. GRB 260531B: Glowbug gamma-ray detection
  15. GRB 260601A: Fermi GBM Observation
  16. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  17. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  18. Fermi GRB 260601A: Global MASTER-Net observations report
  19. GRB 260601A: Fermi GBM Final Real-time Localization
  20. The EP-WXT trigger 01709266272 is likely a flaring star
  21. AT2026nik: EP-FXT X-ray counterpart
  22. Fermi trigger No 801900520: Global MASTER-Net observations report
  23. GRB 260531A: MAXI/GSC detection
  24. AT 2026nuz: COLIBRÍ optical observations
  25. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  26. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  27. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  28. Fermi GRB 260529A: Global MASTER-Net observations report
  29. EP260526a: SVOM/VT optical upper limits
  30. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  31. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  32. EP260527a/GRB 260527A: EP-FXT follow-up observation
  33. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  34. EP260527a: SVOM/VT optical observation
  35. EP260527a: COLIBRÍ optical detection
  36. EP260527a: Einstein Probe detection of a fast X-ray transient
  37. Fermi trigger No 801580882: Global MASTER-Net observations report
  38. EP260526a: LCO optical upper limits
  39. EP260526a: Einstein Probe detection of a fast X-ray transient
  40. EP260526.405: COLIBRÍ optical upper limits
  41. The EP-WXT trigger 01709266106 is not a real source
  42. Fermi GRB 260526A: Global MASTER-Net observations report
  43. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  44. EP-WXT 01709266106: NOT optical upper limits
  45. Fermi GRB 260525A: Global MASTER-Net observations report
  46. GRB 260523B: AstroSat CZTI detection
  47. Fermi GRB 260523A: Global MASTER-Net observations report
  48. GRB 260522A: Fermi GBM Observation
  49. GRB 260522B: NuSTAR detection of prompt emission
  50. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  51. Fermi trigger No 801135305: Global MASTER-Net observations report
  52. Fermi GRB 260522A: Global MASTER-Net observations report
  53. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  54. GRB 260511A: iTelescope T-75 optical detection
  55. GRB 260520B: SVOM/GRM observation
  56. GRB 260411B: TERI Gamma-ray detection
  57. GRB 260407A: TERI Gamma-ray detection
  58. GRB 260307A: TERI Gamma-ray detection
  59. GRB 260225D: TERI Gamma-ray detection
  60. GRB 251118A: TERI Gamma-ray detection
  61. GRB 251113A: TERI Gamma-ray detection
  62. GRB 260428A: TERI Gamma-ray detection
  63. GRB 260519C: NuSTAR detection of prompt emission
  64. Konus-Wind detection of GRB 260518A
  65. GRB 260516D: SVOM/ECLAIRs refined analysis
  66. GRB 260421B: radio detection with the VLA
  67. GRB 260509A: CrAO ZTSh optical upper limit
  68. GRB 260516D: GOTO optical counterpart detection
  69. GRB 260516D: LCO optical observations
  70. GRB 260515A: further Liverpool Telescope observations
  71. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  72. GRB 260516D: GROWTH-India Telescope optical detection
  73. GRB 260516D: SVOM/VT optical bright candidate
  74. GRB 260515A: CrAO ZTSh BVRI optical observations
  75. Fermi GRB 260516C: Global MASTER-Net observations report
  76. SVOM GRB260516D: Global MASTER-Net observations report
  77. GRB 260516D: SVOM possible detection of a burst
  78. GRB 260515A: LCO optical counterpart detection
  79. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  80. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  81. EP260514a: NOT optical counterpart confirmation
  82. EP260514a: TRT optical counterpart candidate
  83. EP260514a: SVOM/VT optical candidate
  84. Fermi GRB 260516B: Global MASTER-Net observations report
  85. GRB 260515A: OHP/T193 optical observations
  86. EP260514a: COLIBRÍ optical upper limits
  87. GRB 260515A: LCO optical observations
  88. SVOM GRB 260515A: Global MASTER-Net observations report
  89. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  90. GRB 260515A: SVOM/VT optical candidate from VHF data
  91. GRB 260515A: JinShan optical counterpart candidate
  92. GRB 260515A: SVOM detection of a burst
  93. GRB 260510C: Glowbug gamma-ray detection
  94. EP260514a: GROWTH-India Telescope optical upper limit
  95. GRB 260511B: GMG Optical Upper Limit
  96. EP260514a: Global MASTER-Net observations report
  97. EP260514a: Einstein Probe detection of a fast X-ray transient
  98. EP260512a: LCO optical upper limits
  99. GRB 260511B: Mephisto multi-band optical followup
  100. Fermi GRB 260514A: Global MASTER-Net observations report

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