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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"

27032 results found.

  1. Fermi GRB 260604C: Global MASTER-Net observations report
  2. Fermi GRB 260604C: Global MASTER-Net observations report
  3. SVOM GRB260604.85: Global MASTER-Net observations report
  4. GRB 260604C: SVOM detection of a long burst
  5. GRB 260604C: Fermi GBM Final Real-time Localization
  6. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  7. GRB 260603A: NOT optical observations
  8. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  9. GRB 260604B: Fermi GBM Final Real-time Localization
  10. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  11. EP260602a: EP-FXT follow-up observation
  12. EP260603a: Global MASTER-Net observations report
  13. EP260603a: Einstein Probe detection of a fast X-ray transient
  14. GRB 260604A: Fermi GBM Final Real-time Localization
  15. EP260602b: Liverpool Telescope observations
  16. EP260602a: Liverpool Telescope optical upper limits
  17. GRB 260603B: Fermi GBM Final Localization
  18. GRB 260603A: EP-FXT follow-up observation
  19. EP260601a/GRB 260601B: EP-FXT follow-up observation
  20. EP260602b: EP-FXT follow-up observation
  21. GRB 260603A: Kilonova-Catcher optical upper limit
  22. GRB 260603A: SVOM/VT optical observations
  23. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  24. EP260602d: Einstein Probe detection of a fast X-ray transient
  25. Fermi trigger No 802141998: Global MASTER-Net observations report
  26. GRB 260601A: SVOM/GRM observation of a short burst
  27. EP260602c: Einstein Probe detection of a fast X-ray transient
  28. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  29. EP260602a: COLIBRÍ optical observations
  30. GRB260601B/EP260601a: NOT near-infrared observations
  31. SVOM GRB260603.23: Global MASTER-Net observations report
  32. GRB 260603A: SVOM detection of a burst
  33. EP260602b: Einstein Probe detection of a fast X-ray transient
  34. Fermi GRB 260602B: Global MASTER-Net observations report
  35. Fermi GRB 260602B: Global MASTER-Net observations report
  36. EP260602a: SVOM/VT optical candidate
  37. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  38. GRB 260602B: Fermi GBM Final Localization
  39. GRB 260601A: GECAM-B observation of a short burst
  40. GRB 260601B/EP260601a: J-band upper limit with WINTER
  41. GRB 260602A: Fermi GBM Final Real-time Localization
  42. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  43. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  44. EP260602a: Einstein Probe detection of a fast X-ray transient
  45. GRB 260601B/EP260601a: SVOM/VT optical observations
  46. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  47. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  48. EP260601a: Einstein Probe detection of an X-ray transient
  49. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  50. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  51. GRB 260601A: Glowbug gamma-ray detection of a short burst
  52. GRB 260516D: VLA radio detection
  53. GRB 260601A: Fermi GBM Observation
  54. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  55. Fermi GRB 260601A: Global MASTER-Net observations report
  56. GRB 260601A: Fermi GBM Final Real-time Localization
  57. GRB 260531B: GECAM-B observation
  58. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  59. The EP-WXT trigger 01709266272 is likely a flaring star
  60. GRB 260531C: Fermi GBM Final Localization Correction
  61. Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
  62. Fermi trigger No 801900520: Global MASTER-Net observations report
  63. GRB 260531B: Fermi GBM Final Real-time Localization
  64. AT 2026nuz: COLIBRÍ optical observations
  65. IPN triangulation of GRB 260527A / EP260527a
  66. EP260527a/GRB 260527A: further FTW optical and NIR observations
  67. GRB 260530B: SVOM/GRM detection of a possible bright short GRB
  68. GRB 260530A: Fermi GBM Final Real-time Localization
  69. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  70. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  71. GRB 260529A: GOTO tentative optical afterglow candidate
  72. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  73. Fermi GRB 260529A: Global MASTER-Net observations report
  74. GRB 260529A: Fermi GBM Final Real-time Localization
  75. EP260526a: SVOM/VT optical upper limits
  76. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  77. EP260527a / GRB 260527A: NOT optical observations
  78. GRB 260527A/EP260527a: FTW optical and NIR observations
  79. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  80. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  81. EP260527a/GRB 260527A: EP-FXT follow-up observation
  82. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  83. GRB 260526A: GECAM-B observation
  84. EP260526a: EP-FXT follow-up observation
  85. EP260527a: SVOM/VT optical observation
  86. EP260527a: COLIBRÍ optical detection
  87. EP260527a: Einstein Probe detection of a fast X-ray transient
  88. The EP-WXT trigger 01709266172 is likely a flaring star
  89. The EP-WXT trigger 01709266147 is likely a flaring star
  90. Fermi trigger No 801580882: Global MASTER-Net observations report
  91. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  92. EP260526a: Einstein Probe detection of a fast X-ray transient
  93. EP260526.405: COLIBRÍ optical upper limits
  94. The EP-WXT trigger 01709266106 is not a real source
  95. Fermi GRB 260526A: Global MASTER-Net observations report
  96. GRB 260526A: Fermi GBM Final Real-time Localization
  97. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  98. EP-WXT 01709266106: NOT optical upper limits
  99. Fermi GRB 260525A: Global MASTER-Net observations report
  100. GRB 260525A: Fermi GBM Final Real-time Localization

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