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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"

19261 results found.

  1. GRB 260604C: Fermi GBM Observation
  2. EP260602d: J-band upper limit with WINTER
  3. EP260602b: J-band upper limit with WINTER
  4. GRB 260604C: LAST detection of optical counterpart candidate
  5. GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
  6. Fermi GRB 260604C: Global MASTER-Net observations report
  7. Fermi GRB 260604C: Global MASTER-Net observations report
  8. SVOM GRB260604.85: Global MASTER-Net observations report
  9. GRB 260604C: SVOM detection of a long burst
  10. GRB 260604C: Fermi GBM Final Real-time Localization
  11. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  12. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  13. GRB 260604B: Fermi GBM Final Real-time Localization
  14. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  15. EP260602a: EP-FXT follow-up observation
  16. EP260603a: Global MASTER-Net observations report
  17. EP260603a: Einstein Probe detection of a fast X-ray transient
  18. EP260602d: Optical Upper limits with kinder observations
  19. GRB 260604A: Fermi GBM Final Real-time Localization
  20. EP260602b: Liverpool Telescope observations
  21. EP260602a: Liverpool Telescope optical upper limits
  22. GRB 260603B: Fermi GBM Final Localization
  23. GRB 260603A: EP-FXT follow-up observation
  24. EP260601a/GRB 260601B: EP-FXT follow-up observation
  25. GRB 260601B / EP260601a: Mondy optical upper limit
  26. EP260602b: EP-FXT follow-up observation
  27. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  28. GRB 260603A: SVOM/VT optical observations
  29. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  30. EP260602d: Einstein Probe detection of a fast X-ray transient
  31. Fermi trigger No 802141998: Global MASTER-Net observations report
  32. GRB 260601A: SVOM/GRM observation of a short burst
  33. EP260602c: Einstein Probe detection of a fast X-ray transient
  34. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  35. EP260602a: COLIBRÍ optical observations
  36. GRB260601B/EP260601a: NOT near-infrared observations
  37. SVOM GRB260603.23: Global MASTER-Net observations report
  38. GRB 260603A: SVOM detection of a burst
  39. EP260602b: Einstein Probe detection of a fast X-ray transient
  40. GRB 260601B/EP260601a: Insight-HXMT detection
  41. Fermi GRB 260602B: Global MASTER-Net observations report
  42. Fermi GRB 260602B: Global MASTER-Net observations report
  43. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  44. EP260602a: SVOM/VT optical candidate
  45. GRB 260602B: Fermi GBM Final Localization
  46. GRB 260601A: GECAM-B observation of a short burst
  47. GRB 260601B/EP260601a: J-band upper limit with WINTER
  48. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  49. GRB 260602A: Fermi GBM Final Real-time Localization
  50. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  51. EP260602a: Optical upper limits with Kinder observations
  52. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  53. EP260602a: Einstein Probe detection of a fast X-ray transient
  54. GRB 260601B/EP260601a: SVOM/VT optical observations
  55. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  56. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  57. EP260601a: Einstein Probe detection of an X-ray transient
  58. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  59. GRB 260601A: Glowbug gamma-ray detection of a short burst
  60. GRB 260531B: Glowbug gamma-ray detection
  61. GRB 260516D: VLA radio detection
  62. GRB 260601A: Fermi GBM Observation
  63. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  64. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  65. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  66. Fermi GRB 260601A: Global MASTER-Net observations report
  67. GRB 260601A: Fermi GBM Final Real-time Localization
  68. GRB 260531B: GECAM-B observation
  69. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  70. The EP-WXT trigger 01709266272 is likely a flaring star
  71. GRB 260531C: Fermi GBM Final Localization Correction
  72. Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
  73. AT2026nik: EP-FXT X-ray counterpart
  74. Fermi trigger No 801900520: Global MASTER-Net observations report
  75. GRB 260531B: Fermi GBM Final Real-time Localization
  76. GRB 260531A: MAXI/GSC detection
  77. AT 2026nuz: COLIBRÍ optical observations
  78. EP260527a/GRB 260527A: further FTW optical and NIR observations
  79. GRB 260530B: SVOM/GRM detection of a possible bright short GRB
  80. GRB 260530A: Fermi GBM Final Real-time Localization
  81. GRB 260527A / EP260527a: VLA radio detection
  82. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  83. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  84. GRB 260529A: GOTO tentative optical afterglow candidate
  85. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  86. GRB 260527A/EP260527a: Insight-HXMT detection
  87. Fermi GRB 260529A: Global MASTER-Net observations report
  88. GRB 260529A: Fermi GBM Final Real-time Localization
  89. EP260526a: SVOM/VT optical upper limits
  90. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  91. EP260527a / GRB 260527A: NOT optical observations
  92. GRB 260527A/EP260527a: FTW optical and NIR observations
  93. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  94. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  95. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  96. GRB 260526A: GECAM-B observation
  97. EP260527a: SVOM/VT optical observation
  98. EP260527a: COLIBRÍ optical detection
  99. EP260527a: Einstein Probe detection of a fast X-ray transient
  100. The EP-WXT trigger 01709266172 is likely a flaring star

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