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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"

45443 results found.

  1. GRB 260604C: further SAO RAS optical observations
  2. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  3. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  4. GRB 260608B: Fermi GBM Final Localization
  5. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  6. GRB 260604C: SVOM/C-GFT upper limit
  7. GRB 260607B: AstroSat CZTI detection
  8. GRB 260608A: SVOM detection of a burst
  9. GRB 260608A: Fermi GBM Final Real-time Localization (duplicate submission)
  10. GRB 260608A: Fermi GBM Final Real-time Localization
  11. EP260605a: EP-FXT follow-up observation
  12. GRB 260607A: TRT optical observations
  13. GRB 260604C: GRANDMA further observations
  14. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  15. GRB 260604A: SVOM/GRM detection
  16. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  17. GRB 260607B: Fermi GBM Observation
  18. GRB 260607B: Fermi-LAT detection
  19. GRB 260607B: Fermi GBM Final Localization Correction
  20. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  21. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  22. GRB 260607A: Fermi GBM Final Real-time Localization (duplicate submission)
  23. GRB 260607A: Fermi GBM Final Real-time Localization
  24. GRB 260604C: GECAM-B observation
  25. GRB 260604C: 6 GHz VLA observations
  26. GRB 260604C: SAO RAS optical observations
  27. GRB 260604C: GRANDMA observations
  28. GRB 260604B: SVOM/GRM detection
  29. GRB 260605A: Insight-HXMT/HE detection
  30. GRB260603A: SVOM/ECLAIRs refined analysis
  31. EP260605a: Einstein Probe detection of a fast X-ray transient
  32. EP260603a: COLIBRÍ optical upper limit
  33. GRB 260604A: Glowbug gamma-ray detection
  34. GRB 260604C: LCO optical upper limit
  35. GRB 260604C: Liverpool Telescope optical detection
  36. The EP-WXT trigger 01709267001 is likely a flaring star
  37. EP260602d: EP-FXT follow-up observation
  38. EP260602c: EP-FXT follow-up observation
  39. GRB 260601B / EP260601a: AstroSat CZTI detection
  40. GRB 260527A/EP260527a: 6 GHz VLA observations
  41. GRB 260604C: GOTO detections of the optical afterglow
  42. GRB 260604C: Correction to GCN 44828
  43. GRB 260604C: Kilonova-Catcher optical afterglow detection
  44. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  45. The EP-WXT trigger 01709266798 is likely a flaring star
  46. GRB 260604C: Jinshan optical observations
  47. GRB 260604C: Fermi GBM Observation
  48. EP260602d: J-band upper limit with WINTER
  49. EP260602b: J-band upper limit with WINTER
  50. GRB 260604C: LAST detection of optical counterpart candidate
  51. Fermi GRB 260604C: Global MASTER-Net observations report
  52. Fermi GRB 260604C: Global MASTER-Net observations report
  53. SVOM GRB260604.85: Global MASTER-Net observations report
  54. GRB 260604C: SVOM detection of a long burst
  55. GRB 260604C: Fermi GBM Final Real-time Localization
  56. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  57. GRB 260603A: NOT optical observations
  58. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  59. GRB 260604B: Fermi GBM Final Real-time Localization
  60. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  61. EP260602a: EP-FXT follow-up observation
  62. EP260603a: Global MASTER-Net observations report
  63. EP260603a: Einstein Probe detection of a fast X-ray transient
  64. EP260602d: Optical Upper limits with kinder observations
  65. GRB 260604A: Fermi GBM Final Real-time Localization
  66. EP260602b: Liverpool Telescope observations
  67. EP260602a: Liverpool Telescope optical upper limits
  68. EP260602b: Liverpool Telescope and LCO observations
  69. GRB 260603B: Fermi GBM Final Localization
  70. EP260602a: GTC and Liverpool Telescope optical observations
  71. Konus-Wind detection of GRB 260601B/EP260601a
  72. GRB 260603A: EP-FXT follow-up observation
  73. EP260601a/GRB 260601B: EP-FXT follow-up observation
  74. GRB 260601B / EP260601a: Mondy optical upper limit
  75. EP260602b: EP-FXT follow-up observation
  76. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  77. GRB 260603A: Kilonova-Catcher optical upper limit
  78. GRB 260603A: SVOM/VT optical observations
  79. EP260602a: NOT NIR J-band observations
  80. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  81. EP260602d: Einstein Probe detection of a fast X-ray transient
  82. Fermi trigger No 802141998: Global MASTER-Net observations report
  83. EP260602a: SVOM/VT optical magnitudes correction
  84. GRB 260601A: SVOM/GRM observation of a short burst
  85. EP260602c: Einstein Probe detection of a fast X-ray transient
  86. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  87. EP260602a: COLIBRÍ optical observations
  88. GRB260601B/EP260601a: NOT near-infrared observations
  89. SVOM GRB260603.23: Global MASTER-Net observations report
  90. GRB 260603A: SVOM detection of a burst
  91. EP260602b: Einstein Probe detection of a fast X-ray transient
  92. GRB 260601B/EP260601a: Insight-HXMT detection
  93. Fermi GRB 260602B: Global MASTER-Net observations report
  94. Fermi GRB 260602B: Global MASTER-Net observations report
  95. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  96. EP260602a: SVOM/VT optical candidate
  97. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  98. GRB 260602B: Fermi GBM Final Localization
  99. GRB 260601A: GECAM-B observation of a short burst
  100. GRB 260601B/EP260601a: J-band upper limit with WINTER

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