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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"

26341 results found.

  1. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  2. GRB 260604A: SVOM/GRM detection
  3. GRB 260607B: Fermi GBM Observation
  4. GRB 260607B: Fermi-LAT detection
  5. GRB 260607B: Fermi GBM Final Localization Correction
  6. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  7. GRB 260604C: GECAM-B observation
  8. GRB 260604C: 6 GHz VLA observations
  9. GRB 260604C: SAO RAS optical observations
  10. GRB 260604C: GRANDMA observations
  11. GRB 260604B: SVOM/GRM detection
  12. GRB 260605A: Insight-HXMT/HE detection
  13. GRB260603A: SVOM/ECLAIRs refined analysis
  14. EP260605a: Einstein Probe detection of a fast X-ray transient
  15. EP260603a: COLIBRÍ optical upper limit
  16. GRB 260604A: Glowbug gamma-ray detection
  17. GRB 260604C: LCO optical upper limit
  18. EP260602d: EP-FXT follow-up observation
  19. EP260602c: EP-FXT follow-up observation
  20. GRB 260601B / EP260601a: AstroSat CZTI detection
  21. GRB 260527A/EP260527a: 6 GHz VLA observations
  22. GRB 260604C: GOTO detections of the optical afterglow
  23. GRB 260604C: Kilonova-Catcher optical afterglow detection
  24. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  25. GRB 260604C: Jinshan optical observations
  26. GRB 260604C: Fermi GBM Observation
  27. EP260602d: J-band upper limit with WINTER
  28. EP260602b: J-band upper limit with WINTER
  29. GRB 260604C: LAST detection of optical counterpart candidate
  30. SVOM GRB260604.85: Global MASTER-Net observations report
  31. GRB 260604C: SVOM detection of a long burst
  32. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  33. GRB 260603A: NOT optical observations
  34. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  35. EP260602a: EP-FXT follow-up observation
  36. EP260603a: Einstein Probe detection of a fast X-ray transient
  37. Konus-Wind detection of GRB 260601B/EP260601a
  38. GRB 260603A: EP-FXT follow-up observation
  39. EP260601a/GRB 260601B: EP-FXT follow-up observation
  40. EP260602b: EP-FXT follow-up observation
  41. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  42. GRB 260603A: Kilonova-Catcher optical upper limit
  43. GRB 260603A: SVOM/VT optical observations
  44. EP260602a: NOT NIR J-band observations
  45. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  46. EP260602d: Einstein Probe detection of a fast X-ray transient
  47. EP260602a: SVOM/VT optical magnitudes correction
  48. GRB 260601A: SVOM/GRM observation of a short burst
  49. EP260602c: Einstein Probe detection of a fast X-ray transient
  50. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  51. EP260602a: COLIBRÍ optical observations
  52. SVOM GRB260603.23: Global MASTER-Net observations report
  53. GRB 260603A: SVOM detection of a burst
  54. EP260602b: Einstein Probe detection of a fast X-ray transient
  55. GRB 260601B/EP260601a: Insight-HXMT detection
  56. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  57. EP260602a: SVOM/VT optical candidate
  58. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  59. GRB 260601A: GECAM-B observation of a short burst
  60. GRB 260601B/EP260601a: J-band upper limit with WINTER
  61. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  62. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  63. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  64. EP260602a: Einstein Probe detection of a fast X-ray transient
  65. GRB 260601B/EP260601a: SVOM/VT optical observations
  66. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  67. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  68. EP260601a: Einstein Probe detection of an X-ray transient
  69. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  70. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  71. GRB 260601A: Glowbug gamma-ray detection of a short burst
  72. GRB 260531B: Glowbug gamma-ray detection
  73. GRB 260601A: Fermi GBM Observation
  74. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  75. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  76. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  77. GRB 260531B: GECAM-B observation
  78. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  79. GRB 260531C: Fermi GBM Final Localization Correction
  80. AT 2026nuz: COLIBRÍ optical observations
  81. IPN triangulation of GRB 260527A / EP260527a
  82. GRB 260530B: SVOM/GRM detection of a possible bright short GRB
  83. GRB 260527A / EP260527a: VLA radio detection
  84. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  85. GRB 260529A: GOTO tentative optical afterglow candidate
  86. GRB 260527A/EP260527a: Insight-HXMT detection
  87. EP260526a: SVOM/VT optical upper limits
  88. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  89. EP260527a/GRB 260527A: EP-FXT follow-up observation
  90. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  91. GRB 260526A: GECAM-B observation
  92. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  93. EP260526a: EP-FXT follow-up observation
  94. EP260527a: SVOM/VT optical observation
  95. EP260527a: COLIBRÍ optical detection
  96. EP260527a: Einstein Probe detection of a fast X-ray transient
  97. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  98. EP260526a: LCO optical upper limits
  99. EP260526a: Einstein Probe detection of a fast X-ray transient
  100. GRB 260525A: AstroSat CZTI detection

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