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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"

32509 results found.

  1. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  2. GRB 260607A: Fermi GBM Final Real-time Localization (duplicate submission)
  3. GRB 260604C: GECAM-B observation
  4. GRB 260604C: 6 GHz VLA observations
  5. GRB 260604C: SAO RAS optical observations
  6. GRB 260604C: GRANDMA observations
  7. GRB 260604B: SVOM/GRM detection
  8. GRB260603A: SVOM/ECLAIRs refined analysis
  9. EP260603a: COLIBRÍ optical upper limit
  10. GRB 260604A: Glowbug gamma-ray detection
  11. GRB 260604C: LCO optical upper limit
  12. GRB 260604C: Liverpool Telescope optical detection
  13. EP260602d: EP-FXT follow-up observation
  14. EP260602c: EP-FXT follow-up observation
  15. GRB 260601B / EP260601a: AstroSat CZTI detection
  16. GRB 260527A/EP260527a: 6 GHz VLA observations
  17. GRB 260604C: GOTO detections of the optical afterglow
  18. GRB 260604C: Correction to GCN 44828
  19. GRB 260604C: Kilonova-Catcher optical afterglow detection
  20. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  21. GRB 260604C: Jinshan optical observations
  22. GRB 260604C: Fermi GBM Observation
  23. EP260602d: J-band upper limit with WINTER
  24. EP260602b: J-band upper limit with WINTER
  25. GRB 260604C: LAST detection of optical counterpart candidate
  26. Fermi GRB 260604C: Global MASTER-Net observations report
  27. Fermi GRB 260604C: Global MASTER-Net observations report
  28. GRB 260604C: SVOM detection of a long burst
  29. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  30. GRB 260603A: NOT optical observations
  31. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  32. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  33. EP260602a: EP-FXT follow-up observation
  34. EP260603a: Global MASTER-Net observations report
  35. EP260602d: Optical Upper limits with kinder observations
  36. EP260602b: Liverpool Telescope observations
  37. EP260602a: Liverpool Telescope optical upper limits
  38. EP260602b: Liverpool Telescope and LCO observations
  39. EP260602a: GTC and Liverpool Telescope optical observations
  40. Konus-Wind detection of GRB 260601B/EP260601a
  41. GRB 260603A: EP-FXT follow-up observation
  42. EP260601a/GRB 260601B: EP-FXT follow-up observation
  43. GRB 260601B / EP260601a: Mondy optical upper limit
  44. EP260602b: EP-FXT follow-up observation
  45. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  46. GRB 260603A: Kilonova-Catcher optical upper limit
  47. GRB 260603A: SVOM/VT optical observations
  48. EP260602a: NOT NIR J-band observations
  49. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  50. EP260602d: Einstein Probe detection of a fast X-ray transient
  51. EP260602a: SVOM/VT optical magnitudes correction
  52. GRB 260601A: SVOM/GRM observation of a short burst
  53. EP260602c: Einstein Probe detection of a fast X-ray transient
  54. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  55. EP260602a: COLIBRÍ optical observations
  56. GRB260601B/EP260601a: NOT near-infrared observations
  57. EP260602b: Einstein Probe detection of a fast X-ray transient
  58. GRB 260601B/EP260601a: Insight-HXMT detection
  59. Fermi GRB 260602B: Global MASTER-Net observations report
  60. Fermi GRB 260602B: Global MASTER-Net observations report
  61. EP260602a: SVOM/VT optical candidate
  62. GRB 260601A: GECAM-B observation of a short burst
  63. GRB 260601B/EP260601a: J-band upper limit with WINTER
  64. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  65. EP260530a/AT 2026nwl: KAIT optical observations
  66. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  67. EP260602a: Optical upper limits with Kinder observations
  68. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  69. GRB 260601B/EP260601a: SVOM/VT optical observations
  70. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  71. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  72. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  73. GRB 260601A: Glowbug gamma-ray detection of a short burst
  74. GRB 260531B: Glowbug gamma-ray detection
  75. GRB 260516D: VLA radio detection
  76. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  77. Fermi GRB 260601A: Global MASTER-Net observations report
  78. GRB 260531B: GECAM-B observation
  79. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  80. AT 2026nuz: COLIBRÍ optical observations
  81. IPN triangulation of GRB 260527A / EP260527a
  82. EP260527a/GRB 260527A: further FTW optical and NIR observations
  83. GRB 260527A / EP260527a: VLA radio detection
  84. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  85. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  86. GRB 260529A: GOTO tentative optical afterglow candidate
  87. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  88. GRB 260527A/EP260527a: Insight-HXMT detection
  89. Fermi GRB 260529A: Global MASTER-Net observations report
  90. EP260526a: SVOM/VT optical upper limits
  91. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  92. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  93. EP260527a / GRB 260527A: NOT optical observations
  94. GRB 260527A/EP260527a: FTW optical and NIR observations
  95. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  96. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  97. EP260527a/GRB 260527A: EP-FXT follow-up observation
  98. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  99. GRB 260526A: GECAM-B observation
  100. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a

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