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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"

32498 results found.

  1. EP260602d: EP-FXT follow-up observation
  2. EP260602c: EP-FXT follow-up observation
  3. GRB 260601B / EP260601a: AstroSat CZTI detection
  4. GRB 260527A/EP260527a: 6 GHz VLA observations
  5. GRB 260604C: GOTO detections of the optical afterglow
  6. GRB 260604C: Correction to GCN 44828
  7. GRB 260604C: Kilonova-Catcher optical afterglow detection
  8. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  9. GRB 260604C: Jinshan optical observations
  10. GRB 260604C: Fermi GBM Observation
  11. EP260602d: J-band upper limit with WINTER
  12. EP260602b: J-band upper limit with WINTER
  13. GRB 260604C: LAST detection of optical counterpart candidate
  14. Fermi GRB 260604C: Global MASTER-Net observations report
  15. Fermi GRB 260604C: Global MASTER-Net observations report
  16. GRB 260604C: SVOM detection of a long burst
  17. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  18. GRB 260603A: NOT optical observations
  19. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  20. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  21. EP260602a: EP-FXT follow-up observation
  22. EP260603a: Global MASTER-Net observations report
  23. EP260602d: Optical Upper limits with kinder observations
  24. EP260602b: Liverpool Telescope observations
  25. EP260602a: Liverpool Telescope optical upper limits
  26. EP260602b: Liverpool Telescope and LCO observations
  27. EP260602a: GTC and Liverpool Telescope optical observations
  28. Konus-Wind detection of GRB 260601B/EP260601a
  29. GRB 260603A: EP-FXT follow-up observation
  30. EP260601a/GRB 260601B: EP-FXT follow-up observation
  31. GRB 260601B / EP260601a: Mondy optical upper limit
  32. EP260602b: EP-FXT follow-up observation
  33. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  34. GRB 260603A: Kilonova-Catcher optical upper limit
  35. GRB 260603A: SVOM/VT optical observations
  36. EP260602a: NOT NIR J-band observations
  37. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  38. EP260602d: Einstein Probe detection of a fast X-ray transient
  39. EP260602a: SVOM/VT optical magnitudes correction
  40. GRB 260601A: SVOM/GRM observation of a short burst
  41. EP260602c: Einstein Probe detection of a fast X-ray transient
  42. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  43. EP260602a: COLIBRÍ optical observations
  44. GRB260601B/EP260601a: NOT near-infrared observations
  45. EP260602b: Einstein Probe detection of a fast X-ray transient
  46. GRB 260601B/EP260601a: Insight-HXMT detection
  47. Fermi GRB 260602B: Global MASTER-Net observations report
  48. Fermi GRB 260602B: Global MASTER-Net observations report
  49. EP260602a: SVOM/VT optical candidate
  50. GRB 260601A: GECAM-B observation of a short burst
  51. GRB 260601B/EP260601a: J-band upper limit with WINTER
  52. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  53. EP260530a/AT 2026nwl: KAIT optical observations
  54. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  55. EP260602a: Optical upper limits with Kinder observations
  56. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  57. GRB 260601B/EP260601a: SVOM/VT optical observations
  58. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  59. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  60. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  61. GRB 260601A: Glowbug gamma-ray detection of a short burst
  62. GRB 260531B: Glowbug gamma-ray detection
  63. GRB 260516D: VLA radio detection
  64. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  65. Fermi GRB 260601A: Global MASTER-Net observations report
  66. GRB 260531B: GECAM-B observation
  67. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  68. AT 2026nuz: COLIBRÍ optical observations
  69. IPN triangulation of GRB 260527A / EP260527a
  70. EP260527a/GRB 260527A: further FTW optical and NIR observations
  71. GRB 260527A / EP260527a: VLA radio detection
  72. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  73. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  74. GRB 260529A: GOTO tentative optical afterglow candidate
  75. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  76. GRB 260527A/EP260527a: Insight-HXMT detection
  77. Fermi GRB 260529A: Global MASTER-Net observations report
  78. EP260526a: SVOM/VT optical upper limits
  79. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  80. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  81. EP260527a / GRB 260527A: NOT optical observations
  82. GRB 260527A/EP260527a: FTW optical and NIR observations
  83. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  84. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  85. EP260527a/GRB 260527A: EP-FXT follow-up observation
  86. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  87. GRB 260526A: GECAM-B observation
  88. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  89. EP260526a: EP-FXT follow-up observation
  90. EP260527a: SVOM/VT optical observation
  91. EP260527a: COLIBRÍ optical detection
  92. EP260526a: LCO optical upper limits
  93. EP260526a: Einstein Probe detection of a fast X-ray transient
  94. GRB 260525A: AstroSat CZTI detection
  95. The EP-WXT trigger 01709266106 is not a real source
  96. Fermi GRB 260526A: Global MASTER-Net observations report
  97. Fermi GRB 260525A: Global MASTER-Net observations report
  98. GRB 260523B: AstroSat CZTI detection
  99. GRB 260523B: GECAM-B observation
  100. Fermi GRB 260523A: Global MASTER-Net observations report

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