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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"

21795 results found.

  1. GRB 260601B / EP260601a: Mondy optical upper limit
  2. EP260602b: EP-FXT follow-up observation
  3. GRB 260603A: Kilonova-Catcher optical upper limit
  4. GRB 260603A: SVOM/VT optical observations
  5. EP260602a: NOT NIR J-band observations
  6. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  7. EP260602d: Einstein Probe detection of a fast X-ray transient
  8. GRB 260601A: SVOM/GRM observation of a short burst
  9. EP260602c: Einstein Probe detection of a fast X-ray transient
  10. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  11. EP260602a: COLIBRÍ optical observations
  12. GRB260601B/EP260601a: NOT near-infrared observations
  13. GRB 260603A: SVOM detection of a burst
  14. EP260602b: Einstein Probe detection of a fast X-ray transient
  15. EP260602a: SVOM/VT optical candidate
  16. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  17. GRB 260601B/EP260601a: J-band upper limit with WINTER
  18. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  19. EP260530a/AT 2026nwl: KAIT optical observations
  20. EP260602a: Optical upper limits with Kinder observations
  21. EP260602a: Einstein Probe detection of a fast X-ray transient
  22. GRB 260601B/EP260601a: SVOM/VT optical observations
  23. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  24. EP260601a: Einstein Probe detection of an X-ray transient
  25. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  26. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  27. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  28. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  29. GRB 260531B: GECAM-B observation
  30. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  31. AT2026nik: EP-FXT X-ray counterpart
  32. AT 2026nuz: COLIBRÍ optical observations
  33. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  34. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  35. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  36. EP260526a: SVOM/VT optical upper limits
  37. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  38. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  39. EP260527a/GRB 260527A: EP-FXT follow-up observation
  40. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  41. EP260527a: SVOM/VT optical observation
  42. EP260527a: COLIBRÍ optical detection
  43. EP260527a: Einstein Probe detection of a fast X-ray transient
  44. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  45. EP260526a: LCO optical upper limits
  46. EP260526a: Einstein Probe detection of a fast X-ray transient
  47. EP260526.405: COLIBRÍ optical upper limits
  48. The EP-WXT trigger 01709266106 is not a real source
  49. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  50. EP-WXT 01709266106: NOT optical upper limits
  51. GRB 260522A: GOTO optical upper limit
  52. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  53. GRB 260522A: Fermi-LAT detection
  54. GRB 260519C: SVOM/GRM observation
  55. GRB 260511A: iTelescope T-75 optical detection
  56. GRB 260520B: SVOM/GRM observation
  57. Konus-Wind detection of GRB 260519C
  58. GRB 260509A: SVOM/ECLAIRs refined analysis
  59. GRB 260518A: AstroSat CZTI detection of a long burst
  60. GRB 260516D: SVOM/ECLAIRs refined analysis
  61. GRB 260515A: SVOM/ECLAIRs refined analysis
  62. GRB 260421B: radio detection with the VLA
  63. GRB 260509A: CrAO ZTSh optical upper limit
  64. GRB 260516D: GOTO optical counterpart detection
  65. GRB 260516D: LCO optical observations
  66. GRB 260515A: further Liverpool Telescope observations
  67. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  68. GRB 260516D: GROWTH-India Telescope optical detection
  69. GRB 260516D: SVOM/VT optical bright candidate
  70. GRB 260515A: CrAO ZTSh BVRI optical observations
  71. GRB 260516D: SVOM possible detection of a burst
  72. GRB 260515A: Liverpool Telescope optical detection
  73. GRB 260515A: LCO optical counterpart detection
  74. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  75. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  76. EP260514a: NOT optical counterpart confirmation
  77. EP260514a: TRT optical counterpart candidate
  78. EP260514a: SVOM/VT optical candidate
  79. GRB 260515A: OHP/T193 optical observations
  80. EP260514a: COLIBRÍ optical upper limits
  81. GRB 260515A: LCO optical observations
  82. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  83. GRB 260515A: SVOM/VT optical candidate from VHF data
  84. GRB 260515A: JinShan optical counterpart candidate
  85. GRB 260515A: SVOM detection of a burst
  86. EP260514a: GROWTH-India Telescope optical upper limit
  87. Konus-Wind detection of GRB 260512A
  88. GRB 260511B: GMG Optical Upper Limit
  89. EP260514a: Einstein Probe detection of a fast X-ray transient
  90. EP260512a: LCO optical upper limits
  91. GRB 260511B: Mephisto multi-band optical followup
  92. GRB 260512A: AstroSat CZTI detection
  93. EP260512a: EP-FXT follow-up observation
  94. EP260507a: Xinglong Schmidt optical counterpart detection
  95. GRB 260511B: further SAO RAS optical observations
  96. Konus-Wind detection of GRB 260511B
  97. EP260512a: COLIBRÍ optical upper limits
  98. EP260512a: Einstein Probe detection of an X-ray transient
  99. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  100. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.

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