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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"

32501 results found.

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

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