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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

24364 results found.

  1. GRB 260604C: GOTO detections of the optical afterglow
  2. The EP-WXT trigger 01709266798 is likely a flaring star
  3. GRB 260604C: Fermi GBM Observation
  4. EP260602d: J-band upper limit with WINTER
  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 260604B: Fermi GBM Final Real-time Localization
  12. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  13. EP260602a: EP-FXT follow-up observation
  14. EP260603a: Global MASTER-Net observations report
  15. GRB 260604A: Fermi GBM Final Real-time Localization
  16. EP260602a: Liverpool Telescope optical upper limits
  17. GRB 260603B: Fermi GBM Final Localization
  18. Konus-Wind detection of GRB 260601B/EP260601a
  19. GRB 260603A: EP-FXT follow-up observation
  20. EP260601a/GRB 260601B: EP-FXT follow-up observation
  21. EP260602b: EP-FXT follow-up observation
  22. GRB 260603A: SVOM/VT optical observations
  23. EP260602a: NOT NIR J-band observations
  24. Fermi trigger No 802141998: Global MASTER-Net observations report
  25. EP260602a: SVOM/VT optical magnitudes correction
  26. GRB 260601A: SVOM/GRM observation of a short burst
  27. GRB260601B/EP260601a: NOT near-infrared observations
  28. SVOM GRB260603.23: Global MASTER-Net observations report
  29. GRB 260603A: SVOM detection of a burst
  30. Fermi GRB 260602B: Global MASTER-Net observations report
  31. Fermi GRB 260602B: Global MASTER-Net observations report
  32. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  33. EP260602a: SVOM/VT optical candidate
  34. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  35. GRB 260602B: Fermi GBM Final Localization
  36. GRB 260602A: Fermi GBM Final Real-time Localization
  37. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  38. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  39. GRB 260601B/EP260601a: SVOM/VT optical observations
  40. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  41. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  42. EP260601a: Einstein Probe detection of an X-ray transient
  43. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  44. GRB 260516D: VLA radio detection
  45. GRB 260601A: Fermi GBM Observation
  46. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  47. Fermi GRB 260601A: Global MASTER-Net observations report
  48. GRB 260601A: Fermi GBM Final Real-time Localization
  49. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  50. The EP-WXT trigger 01709266272 is likely a flaring star
  51. GRB 260531C: Fermi GBM Final Localization Correction
  52. AT2026nik: EP-FXT X-ray counterpart
  53. Fermi trigger No 801900520: Global MASTER-Net observations report
  54. GRB 260531B: Fermi GBM Final Real-time Localization
  55. GRB 260531A: MAXI/GSC detection
  56. IPN triangulation of GRB 260527A / EP260527a
  57. GRB 260530B: SVOM/GRM detection of a possible bright short GRB
  58. GRB 260530A: Fermi GBM Final Real-time Localization
  59. GRB 260527A / EP260527a: VLA radio detection
  60. GRB 260529A: GOTO tentative optical afterglow candidate
  61. Fermi GRB 260529A: Global MASTER-Net observations report
  62. GRB 260529A: Fermi GBM Final Real-time Localization
  63. EP260526a: SVOM/VT optical upper limits
  64. EP260527a / GRB 260527A: NOT optical observations
  65. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  66. EP260527a/GRB 260527A: EP-FXT follow-up observation
  67. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  68. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  69. EP260526a: EP-FXT follow-up observation
  70. EP260527a: SVOM/VT optical observation
  71. The EP-WXT trigger 01709266172 is likely a flaring star
  72. The EP-WXT trigger 01709266147 is likely a flaring star
  73. Fermi trigger No 801580882: Global MASTER-Net observations report
  74. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  75. The EP-WXT trigger 01709266106 is not a real source
  76. Fermi GRB 260526A: Global MASTER-Net observations report
  77. GRB 260526A: Fermi GBM Final Real-time Localization
  78. Fermi GRB 260525A: Global MASTER-Net observations report
  79. GRB 260525A: Fermi GBM Final Real-time Localization
  80. Fermi GRB 260523A: Global MASTER-Net observations report
  81. GRB 260523B: Fermi GBM Final Real-time Localization
  82. GRB 260523A: Fermi GBM Final Real-time Localization
  83. GRB 260522A: Fermi GBM Observation
  84. GRB 260522B: NuSTAR detection of prompt emission
  85. GRB 260522B: Fermi GBM Final Real-time Localization
  86. GRB 260522A: GOTO optical upper limit
  87. Fermi trigger No 801135305: Global MASTER-Net observations report
  88. Fermi GRB 260522A: Global MASTER-Net observations report
  89. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  90. GRB 260522A: Fermi-LAT detection
  91. GRB 260519C: SVOM/GRM observation
  92. GRB 260522A: Fermi GBM Final Real-time Localization
  93. Konus-Wind detection of GRB 260519C
  94. GRB 260520B: Fermi GBM Final Localization
  95. GRB 260509A: SVOM/ECLAIRs refined analysis
  96. GRB 260520A: Fermi GBM Final Localization
  97. GRB 260519D: Fermi GBM Final Localization Correction
  98. GRB 260519C: NuSTAR detection of prompt emission
  99. Konus-Wind detection of GRB 260518A
  100. GRB 260519B: Fermi GBM Final Localization

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