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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"

19260 results found.

  1. EP260602d: J-band upper limit with WINTER
  2. EP260602b: J-band upper limit with WINTER
  3. GRB 260604C: LAST detection of optical counterpart candidate
  4. GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
  5. Fermi GRB 260604C: Global MASTER-Net observations report
  6. Fermi GRB 260604C: Global MASTER-Net observations report
  7. SVOM GRB260604.85: Global MASTER-Net observations report
  8. GRB 260604C: SVOM detection of a long burst
  9. GRB 260604C: Fermi GBM Final Real-time Localization
  10. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  11. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  12. GRB 260604B: Fermi GBM Final Real-time Localization
  13. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  14. EP260602a: EP-FXT follow-up observation
  15. EP260603a: Global MASTER-Net observations report
  16. EP260603a: Einstein Probe detection of a fast X-ray transient
  17. EP260602d: Optical Upper limits with kinder observations
  18. GRB 260604A: Fermi GBM Final Real-time Localization
  19. EP260602b: Liverpool Telescope observations
  20. EP260602a: Liverpool Telescope optical upper limits
  21. GRB 260603B: Fermi GBM Final Localization
  22. GRB 260603A: EP-FXT follow-up observation
  23. EP260601a/GRB 260601B: EP-FXT follow-up observation
  24. GRB 260601B / EP260601a: Mondy optical upper limit
  25. EP260602b: EP-FXT follow-up observation
  26. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  27. GRB 260603A: SVOM/VT optical observations
  28. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  29. EP260602d: Einstein Probe detection of a fast X-ray transient
  30. Fermi trigger No 802141998: Global MASTER-Net observations report
  31. GRB 260601A: SVOM/GRM observation of a short burst
  32. EP260602c: Einstein Probe detection of a fast X-ray transient
  33. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  34. EP260602a: COLIBRÍ optical observations
  35. GRB260601B/EP260601a: NOT near-infrared observations
  36. SVOM GRB260603.23: Global MASTER-Net observations report
  37. GRB 260603A: SVOM detection of a burst
  38. EP260602b: Einstein Probe detection of a fast X-ray transient
  39. GRB 260601B/EP260601a: Insight-HXMT detection
  40. Fermi GRB 260602B: Global MASTER-Net observations report
  41. Fermi GRB 260602B: Global MASTER-Net observations report
  42. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  43. EP260602a: SVOM/VT optical candidate
  44. GRB 260602B: Fermi GBM Final Localization
  45. GRB 260601A: GECAM-B observation of a short burst
  46. GRB 260601B/EP260601a: J-band upper limit with WINTER
  47. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  48. GRB 260602A: Fermi GBM Final Real-time Localization
  49. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  50. EP260602a: Optical upper limits with Kinder observations
  51. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  52. EP260602a: Einstein Probe detection of a fast X-ray transient
  53. GRB 260601B/EP260601a: SVOM/VT optical observations
  54. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  55. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  56. EP260601a: Einstein Probe detection of an X-ray transient
  57. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  58. GRB 260601A: Glowbug gamma-ray detection of a short burst
  59. GRB 260531B: Glowbug gamma-ray detection
  60. GRB 260516D: VLA radio detection
  61. GRB 260601A: Fermi GBM Observation
  62. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  63. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  64. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  65. Fermi GRB 260601A: Global MASTER-Net observations report
  66. GRB 260601A: Fermi GBM Final Real-time Localization
  67. GRB 260531B: GECAM-B observation
  68. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  69. The EP-WXT trigger 01709266272 is likely a flaring star
  70. GRB 260531C: Fermi GBM Final Localization Correction
  71. Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
  72. AT2026nik: EP-FXT X-ray counterpart
  73. Fermi trigger No 801900520: Global MASTER-Net observations report
  74. GRB 260531B: Fermi GBM Final Real-time Localization
  75. GRB 260531A: MAXI/GSC detection
  76. AT 2026nuz: COLIBRÍ optical observations
  77. EP260527a/GRB 260527A: further FTW optical and NIR observations
  78. GRB 260530B: SVOM/GRM detection of a possible bright short GRB
  79. GRB 260530A: Fermi GBM Final Real-time Localization
  80. GRB 260527A / EP260527a: VLA radio detection
  81. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  82. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  83. GRB 260529A: GOTO tentative optical afterglow candidate
  84. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  85. GRB 260527A/EP260527a: Insight-HXMT detection
  86. Fermi GRB 260529A: Global MASTER-Net observations report
  87. GRB 260529A: Fermi GBM Final Real-time Localization
  88. EP260526a: SVOM/VT optical upper limits
  89. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  90. EP260527a / GRB 260527A: NOT optical observations
  91. GRB 260527A/EP260527a: FTW optical and NIR observations
  92. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  93. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  94. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  95. GRB 260526A: GECAM-B observation
  96. EP260527a: SVOM/VT optical observation
  97. EP260527a: COLIBRÍ optical detection
  98. EP260527a: Einstein Probe detection of a fast X-ray transient
  99. The EP-WXT trigger 01709266172 is likely a flaring star
  100. The EP-WXT trigger 01709266147 is likely a flaring star

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