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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"

2482 results found.

  1. EP260602d: Optical Upper limits with kinder observations
  2. GRB 260604A: Fermi GBM Final Real-time Localization
  3. EP260602b: Liverpool Telescope observations
  4. EP260602a: Liverpool Telescope optical upper limits
  5. GRB 260603B: Fermi GBM Final Localization
  6. GRB 260603A: EP-FXT follow-up observation
  7. EP260601a/GRB 260601B: EP-FXT follow-up observation
  8. GRB 260601B / EP260601a: Mondy optical upper limit
  9. EP260602b: EP-FXT follow-up observation
  10. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  11. GRB 260603A: SVOM/VT optical observations
  12. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  13. EP260602d: Einstein Probe detection of a fast X-ray transient
  14. Fermi trigger No 802141998: Global MASTER-Net observations report
  15. GRB 260601A: SVOM/GRM observation of a short burst
  16. EP260602c: Einstein Probe detection of a fast X-ray transient
  17. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  18. EP260602a: COLIBRÍ optical observations
  19. GRB260601B/EP260601a: NOT near-infrared observations
  20. SVOM GRB260603.23: Global MASTER-Net observations report
  21. GRB 260603A: SVOM detection of a burst
  22. EP260602b: Einstein Probe detection of a fast X-ray transient
  23. GRB 260601B/EP260601a: Insight-HXMT detection
  24. Fermi GRB 260602B: Global MASTER-Net observations report
  25. Fermi GRB 260602B: Global MASTER-Net observations report
  26. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  27. EP260602a: SVOM/VT optical candidate
  28. GRB 260602B: Fermi GBM Final Localization
  29. GRB 260601A: GECAM-B observation of a short burst
  30. GRB 260601B/EP260601a: J-band upper limit with WINTER
  31. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  32. GRB 260602A: Fermi GBM Final Real-time Localization
  33. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  34. EP260602a: Optical upper limits with Kinder observations
  35. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  36. EP260602a: Einstein Probe detection of a fast X-ray transient
  37. GRB 260601B/EP260601a: SVOM/VT optical observations
  38. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  39. EP260601a: Einstein Probe detection of an X-ray transient
  40. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  41. GRB 260601A: Glowbug gamma-ray detection of a short burst
  42. GRB 260531B: Glowbug gamma-ray detection
  43. GRB 260516D: VLA radio detection
  44. GRB 260601A: Fermi GBM Observation
  45. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  46. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  47. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  48. Fermi GRB 260601A: Global MASTER-Net observations report
  49. GRB 260601A: Fermi GBM Final Real-time Localization
  50. GRB 260531B: GECAM-B observation
  51. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  52. The EP-WXT trigger 01709266272 is likely a flaring star
  53. GRB 260531C: Fermi GBM Final Localization Correction
  54. Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
  55. AT2026nik: EP-FXT X-ray counterpart
  56. Fermi trigger No 801900520: Global MASTER-Net observations report
  57. GRB 260531B: Fermi GBM Final Real-time Localization
  58. GRB 260531A: MAXI/GSC detection
  59. AT 2026nuz: COLIBRÍ optical observations
  60. EP260527a/GRB 260527A: further FTW optical and NIR observations
  61. GRB 260530B: SVOM/GRM detection of a possible bright short GRB
  62. GRB 260530A: Fermi GBM Final Real-time Localization
  63. GRB 260527A / EP260527a: VLA radio detection
  64. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  65. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  66. GRB 260529A: GOTO tentative optical afterglow candidate
  67. GRB 260527A/EP260527a: Insight-HXMT detection
  68. Fermi GRB 260529A: Global MASTER-Net observations report
  69. GRB 260529A: Fermi GBM Final Real-time Localization
  70. EP260526a: SVOM/VT optical upper limits
  71. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  72. EP260527a / GRB 260527A: NOT optical observations
  73. GRB 260527A/EP260527a: FTW optical and NIR observations
  74. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  75. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  76. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  77. GRB 260526A: GECAM-B observation
  78. EP260527a: SVOM/VT optical observation
  79. EP260527a: COLIBRÍ optical detection
  80. EP260527a: Einstein Probe detection of a fast X-ray transient
  81. The EP-WXT trigger 01709266172 is likely a flaring star
  82. The EP-WXT trigger 01709266147 is likely a flaring star
  83. Fermi trigger No 801580882: Global MASTER-Net observations report
  84. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  85. EP260526a: LCO optical upper limits
  86. EP260526a: Einstein Probe detection of a fast X-ray transient
  87. GRB 260525A: AstroSat CZTI detection
  88. EP260526.405: COLIBRÍ optical upper limits
  89. The EP-WXT trigger 01709266106 is not a real source
  90. Fermi GRB 260526A: Global MASTER-Net observations report
  91. GRB 260526A: Fermi GBM Final Real-time Localization
  92. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  93. EP-WXT 01709266106: NOT optical upper limits
  94. Fermi GRB 260525A: Global MASTER-Net observations report
  95. GRB 260525A: Fermi GBM Final Real-time Localization
  96. GRB 260523B: AstroSat CZTI detection
  97. GRB 260523B: GECAM-B observation
  98. Fermi GRB 260523A: Global MASTER-Net observations report
  99. GRB 260523B: Fermi GBM Final Real-time Localization
  100. GRB 260523A: Fermi GBM Final Real-time Localization

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