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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"
  1. EP260602b: Liverpool Telescope and LCO observations
  2. GRB 260603B: Fermi GBM Final Localization
  3. EP260602a: GTC and Liverpool Telescope optical observations
  4. Konus-Wind detection of GRB 260601B/EP260601a
  5. GRB 260603A: EP-FXT follow-up observation
  6. EP260601a/GRB 260601B: EP-FXT follow-up observation
  7. GRB 260601B / EP260601a: Mondy optical upper limit
  8. EP260602b: EP-FXT follow-up observation
  9. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  10. GRB 260603A: Kilonova-Catcher optical upper limit
  11. GRB 260603A: SVOM/VT optical observations
  12. EP260602a: NOT NIR J-band observations
  13. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  14. EP260602d: Einstein Probe detection of a fast X-ray transient
  15. Fermi trigger No 802141998: Global MASTER-Net observations report
  16. EP260602a: SVOM/VT optical magnitudes correction
  17. GRB 260601A: SVOM/GRM observation of a short burst
  18. EP260602c: Einstein Probe detection of a fast X-ray transient
  19. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  20. EP260602a: COLIBRÍ optical observations
  21. GRB260601B/EP260601a: NOT near-infrared observations
  22. SVOM GRB260603.23: Global MASTER-Net observations report
  23. GRB 260603A: SVOM detection of a burst
  24. EP260602b: Einstein Probe detection of a fast X-ray transient
  25. GRB 260601B/EP260601a: Insight-HXMT detection
  26. Fermi GRB 260602B: Global MASTER-Net observations report
  27. Fermi GRB 260602B: Global MASTER-Net observations report
  28. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  29. EP260602a: SVOM/VT optical candidate
  30. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  31. GRB 260602B: Fermi GBM Final Localization
  32. GRB 260601A: GECAM-B observation of a short burst
  33. GRB 260601B/EP260601a: J-band upper limit with WINTER
  34. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  35. EP260530a/AT 2026nwl: KAIT optical observations
  36. GRB 260602A: Fermi GBM Final Real-time Localization
  37. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  38. EP260602a: Optical upper limits with Kinder observations
  39. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  40. EP260602a: Einstein Probe detection of a fast X-ray transient
  41. GRB 260601B/EP260601a: SVOM/VT optical observations
  42. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  43. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  44. EP260601a: Einstein Probe detection of an X-ray transient
  45. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  46. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  47. GRB 260601A: Glowbug gamma-ray detection of a short burst
  48. GRB 260531B: Glowbug gamma-ray detection
  49. GRB 260516D: VLA radio detection
  50. GRB 260601A: Fermi GBM Observation
  51. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  52. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  53. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  54. Fermi GRB 260601A: Global MASTER-Net observations report
  55. GRB 260601A: Fermi GBM Final Real-time Localization
  56. GRB 260531B: GECAM-B observation
  57. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  58. The EP-WXT trigger 01709266272 is likely a flaring star
  59. GRB 260531C: Fermi GBM Final Localization Correction
  60. Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
  61. AT2026nik: EP-FXT X-ray counterpart
  62. Fermi trigger No 801900520: Global MASTER-Net observations report
  63. GRB 260531B: Fermi GBM Final Real-time Localization
  64. GRB 260531A: MAXI/GSC detection
  65. AT 2026nuz: COLIBRÍ optical observations
  66. IPN triangulation of GRB 260527A / EP260527a
  67. EP260527a/GRB 260527A: further FTW optical and NIR observations
  68. GRB 260530B: SVOM/GRM detection of a possible bright short GRB
  69. GRB 260530A: Fermi GBM Final Real-time Localization
  70. GRB 260527A / EP260527a: VLA radio detection
  71. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  72. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  73. GRB 260529A: GOTO tentative optical afterglow candidate
  74. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  75. GRB 260527A/EP260527a: Insight-HXMT detection
  76. Fermi GRB 260529A: Global MASTER-Net observations report
  77. GRB 260529A: Fermi GBM Final Real-time Localization
  78. EP260526a: SVOM/VT optical upper limits
  79. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  80. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  81. EP260527a / GRB 260527A: NOT optical observations
  82. GRB 260527A/EP260527a: FTW optical and NIR observations
  83. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  84. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  85. EP260527a/GRB 260527A: EP-FXT follow-up observation
  86. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  87. GRB 260526A: GECAM-B observation
  88. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  89. EP260526a: EP-FXT follow-up observation
  90. EP260527a: SVOM/VT optical observation
  91. EP260527a: COLIBRÍ optical detection
  92. EP260527a: Einstein Probe detection of a fast X-ray transient
  93. The EP-WXT trigger 01709266172 is likely a flaring star
  94. The EP-WXT trigger 01709266147 is likely a flaring star
  95. Fermi trigger No 801580882: Global MASTER-Net observations report
  96. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  97. EP260526a: LCO optical upper limits
  98. EP260526a: Einstein Probe detection of a fast X-ray transient
  99. GRB 260525A: AstroSat CZTI detection
  100. EP260526.405: COLIBRÍ optical upper limits

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