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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"

32505 results found.

  1. GRB 260604C: SAO RAS optical observations
  2. GRB 260604C: GRANDMA observations
  3. GRB 260604B: SVOM/GRM detection
  4. GRB260603A: SVOM/ECLAIRs refined analysis
  5. EP260603a: COLIBRÍ optical upper limit
  6. GRB 260604A: Glowbug gamma-ray detection
  7. GRB 260604C: LCO optical upper limit
  8. GRB 260604C: Liverpool Telescope optical detection
  9. EP260602d: EP-FXT follow-up observation
  10. EP260602c: EP-FXT follow-up observation
  11. GRB 260601B / EP260601a: AstroSat CZTI detection
  12. GRB 260527A/EP260527a: 6 GHz VLA observations
  13. GRB 260604C: GOTO detections of the optical afterglow
  14. GRB 260604C: Correction to GCN 44828
  15. GRB 260604C: Kilonova-Catcher optical afterglow detection
  16. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  17. GRB 260604C: Jinshan optical observations
  18. GRB 260604C: Fermi GBM Observation
  19. EP260602d: J-band upper limit with WINTER
  20. EP260602b: J-band upper limit with WINTER
  21. GRB 260604C: LAST detection of optical counterpart candidate
  22. Fermi GRB 260604C: Global MASTER-Net observations report
  23. Fermi GRB 260604C: Global MASTER-Net observations report
  24. GRB 260604C: SVOM detection of a long burst
  25. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  26. GRB 260603A: NOT optical observations
  27. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  28. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  29. EP260602a: EP-FXT follow-up observation
  30. EP260603a: Global MASTER-Net observations report
  31. EP260602d: Optical Upper limits with kinder observations
  32. EP260602b: Liverpool Telescope observations
  33. EP260602a: Liverpool Telescope optical upper limits
  34. EP260602b: Liverpool Telescope and LCO observations
  35. EP260602a: GTC and Liverpool Telescope optical observations
  36. Konus-Wind detection of GRB 260601B/EP260601a
  37. GRB 260603A: EP-FXT follow-up observation
  38. EP260601a/GRB 260601B: EP-FXT follow-up observation
  39. GRB 260601B / EP260601a: Mondy optical upper limit
  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. GRB260601B/EP260601a: NOT near-infrared observations
  53. EP260602b: Einstein Probe detection of a fast X-ray transient
  54. GRB 260601B/EP260601a: Insight-HXMT detection
  55. Fermi GRB 260602B: Global MASTER-Net observations report
  56. Fermi GRB 260602B: Global MASTER-Net observations report
  57. EP260602a: SVOM/VT optical candidate
  58. GRB 260601A: GECAM-B observation of a short burst
  59. GRB 260601B/EP260601a: J-band upper limit with WINTER
  60. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  61. EP260530a/AT 2026nwl: KAIT optical observations
  62. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  63. EP260602a: Optical upper limits with Kinder observations
  64. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  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. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  69. GRB 260601A: Glowbug gamma-ray detection of a short burst
  70. GRB 260531B: Glowbug gamma-ray detection
  71. GRB 260516D: VLA radio detection
  72. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  73. Fermi GRB 260601A: Global MASTER-Net observations report
  74. GRB 260531B: GECAM-B observation
  75. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  76. AT 2026nuz: COLIBRÍ optical observations
  77. IPN triangulation of GRB 260527A / EP260527a
  78. EP260527a/GRB 260527A: further FTW optical and NIR observations
  79. GRB 260527A / EP260527a: VLA radio detection
  80. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  81. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  82. GRB 260529A: GOTO tentative optical afterglow candidate
  83. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  84. GRB 260527A/EP260527a: Insight-HXMT detection
  85. Fermi GRB 260529A: Global MASTER-Net observations report
  86. EP260526a: SVOM/VT optical upper limits
  87. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  88. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  89. EP260527a / GRB 260527A: NOT optical observations
  90. GRB 260527A/EP260527a: FTW optical and NIR observations
  91. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  92. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  93. EP260527a/GRB 260527A: EP-FXT follow-up observation
  94. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  95. GRB 260526A: GECAM-B observation
  96. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  97. EP260526a: EP-FXT follow-up observation
  98. EP260527a: SVOM/VT optical observation
  99. EP260527a: COLIBRÍ optical detection
  100. EP260526a: LCO optical upper limits

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