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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"

38431 results found.

  1. GRB 260604C: SVOM/C-GFT upper limit
  2. GRB 260607B: AstroSat CZTI detection
  3. GRB 260608A: SVOM detection of a burst
  4. GRB 260608A: Fermi GBM Final Real-time Localization
  5. EP260605a: EP-FXT follow-up observation
  6. GRB 260604C: GRANDMA further observations
  7. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  8. GRB 260604A: SVOM/GRM detection
  9. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  10. GRB 260607B: Fermi GBM Observation
  11. GRB 260607B: Fermi-LAT detection
  12. GRB 260607B: Fermi GBM Final Localization Correction
  13. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  14. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  15. GRB 260607A: Fermi GBM Final Real-time Localization
  16. GRB 260604C: GECAM-B observation
  17. GRB 260604C: 6 GHz VLA observations
  18. GRB 260604C: SAO RAS optical observations
  19. GRB 260604C: GRANDMA observations
  20. GRB 260604B: SVOM/GRM detection
  21. GRB 260605A: Insight-HXMT/HE detection
  22. GRB260603A: SVOM/ECLAIRs refined analysis
  23. EP260605a: Einstein Probe detection of a fast X-ray transient
  24. EP260603a: COLIBRÍ optical upper limit
  25. GRB 260604A: Glowbug gamma-ray detection
  26. GRB 260604C: LCO optical upper limit
  27. GRB 260604C: Liverpool Telescope optical detection
  28. The EP-WXT trigger 01709267001 is likely a flaring star
  29. EP260602d: EP-FXT follow-up observation
  30. EP260602c: EP-FXT follow-up observation
  31. GRB 260601B / EP260601a: AstroSat CZTI detection
  32. GRB 260527A/EP260527a: 6 GHz VLA observations
  33. GRB 260604C: GOTO detections of the optical afterglow
  34. GRB 260604C: Correction to GCN 44828
  35. GRB 260604C: Kilonova-Catcher optical afterglow detection
  36. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  37. The EP-WXT trigger 01709266798 is likely a flaring star
  38. GRB 260604C: Jinshan optical observations
  39. GRB 260604C: Fermi GBM Observation
  40. GRB 260604C: LAST detection of optical counterpart candidate
  41. GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
  42. SVOM GRB260604.85: Global MASTER-Net observations report
  43. GRB 260604C: SVOM detection of a long burst
  44. GRB 260604C: Fermi GBM Final Real-time Localization
  45. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  46. GRB 260603A: NOT optical observations
  47. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  48. GRB 260604B: Fermi GBM Final Real-time Localization
  49. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  50. EP260602a: EP-FXT follow-up observation
  51. EP260603a: Einstein Probe detection of a fast X-ray transient
  52. EP260602d: Optical Upper limits with kinder observations
  53. GRB 260604A: Fermi GBM Final Real-time Localization
  54. EP260602b: Liverpool Telescope observations
  55. EP260602a: Liverpool Telescope optical upper limits
  56. EP260602b: Liverpool Telescope and LCO observations
  57. GRB 260603B: Fermi GBM Final Localization
  58. EP260602a: GTC and Liverpool Telescope optical observations
  59. Konus-Wind detection of GRB 260601B/EP260601a
  60. GRB 260603A: EP-FXT follow-up observation
  61. EP260601a/GRB 260601B: EP-FXT follow-up observation
  62. GRB 260601B / EP260601a: Mondy optical upper limit
  63. EP260602b: EP-FXT follow-up observation
  64. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  65. GRB 260603A: Kilonova-Catcher optical upper limit
  66. GRB 260603A: SVOM/VT optical observations
  67. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  68. EP260602d: Einstein Probe detection of a fast X-ray transient
  69. EP260602a: SVOM/VT optical magnitudes correction
  70. GRB 260601A: SVOM/GRM observation of a short burst
  71. EP260602c: Einstein Probe detection of a fast X-ray transient
  72. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  73. EP260602a: COLIBRÍ optical observations
  74. SVOM GRB260603.23: Global MASTER-Net observations report
  75. GRB 260603A: SVOM detection of a burst
  76. EP260602b: Einstein Probe detection of a fast X-ray transient
  77. GRB 260601B/EP260601a: Insight-HXMT detection
  78. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  79. EP260602a: SVOM/VT optical candidate
  80. GRB 260602B: Fermi GBM Final Localization
  81. GRB 260601A: GECAM-B observation of a short burst
  82. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  83. EP260530a/AT 2026nwl: KAIT optical observations
  84. GRB 260602A: Fermi GBM Final Real-time Localization
  85. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  86. EP260602a: Optical upper limits with Kinder observations
  87. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  88. EP260602a: Einstein Probe detection of a fast X-ray transient
  89. GRB 260601B/EP260601a: SVOM/VT optical observations
  90. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  91. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  92. EP260601a: Einstein Probe detection of an X-ray transient
  93. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  94. GRB 260601A: Glowbug gamma-ray detection of a short burst
  95. GRB 260531B: Glowbug gamma-ray detection
  96. GRB 260516D: VLA radio detection
  97. GRB 260601A: Fermi GBM Observation
  98. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  99. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  100. GRB 260527A/EP260527a: Glowbug gamma-ray detection

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