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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"

15247 results found.

  1. GRB 260604A: SVOM/GRM detection
  2. GRB 260607B: Fermi GBM Observation
  3. GRB 260607B: Fermi-LAT detection
  4. GRB 260604C: GECAM-B observation
  5. GRB 260604C: GRANDMA observations
  6. GRB 260604B: SVOM/GRM detection
  7. GRB 260605A: Insight-HXMT/HE detection
  8. GRB260603A: SVOM/ECLAIRs refined analysis
  9. EP260605a: Einstein Probe detection of a fast X-ray transient
  10. The EP-WXT trigger 01709267001 is likely a flaring star
  11. GRB 260601B / EP260601a: AstroSat CZTI detection
  12. GRB 260527A/EP260527a: 6 GHz VLA observations
  13. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  14. The EP-WXT trigger 01709266798 is likely a flaring star
  15. GRB 260604C: Jinshan optical observations
  16. GRB 260604C: Fermi GBM Observation
  17. GRB 260604C: LAST detection of optical counterpart candidate
  18. GRB 260604C: SVOM detection of a long burst
  19. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  20. Konus-Wind detection of GRB 260601B/EP260601a
  21. EP260601a/GRB 260601B: EP-FXT follow-up observation
  22. GRB 260601B / EP260601a: Mondy optical upper limit
  23. GRB 260603A: Kilonova-Catcher optical upper limit
  24. EP260602a: NOT NIR J-band observations
  25. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  26. GRB 260601A: SVOM/GRM observation of a short burst
  27. EP260602a: COLIBRÍ optical observations
  28. GRB260601B/EP260601a: NOT near-infrared observations
  29. GRB 260603A: SVOM detection of a burst
  30. EP260602b: Einstein Probe detection of a fast X-ray transient
  31. GRB 260601B/EP260601a: Insight-HXMT detection
  32. GRB 260601A: GECAM-B observation of a short burst
  33. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  34. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  35. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  36. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  37. GRB 260601A: Fermi GBM Observation
  38. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  39. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  40. GRB 260531B: GECAM-B observation
  41. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  42. AT2026nik: EP-FXT X-ray counterpart
  43. AT 2026nuz: COLIBRÍ optical observations
  44. GRB 260530B: SVOM/GRM detection of a possible bright short GRB
  45. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  46. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  47. GRB 260527A/EP260527a: Insight-HXMT detection
  48. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  49. EP260527a / GRB 260527A: NOT optical observations
  50. GRB 260527A/EP260527a: FTW optical and NIR observations
  51. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  52. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  53. GRB 260526A: GECAM-B observation
  54. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  55. EP260527a: COLIBRÍ optical detection
  56. The EP-WXT trigger 01709266172 is likely a flaring star
  57. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  58. EP260526a: LCO optical upper limits
  59. GRB 260525A: AstroSat CZTI detection
  60. EP260526.405: COLIBRÍ optical upper limits
  61. GRB 260523B: AstroSat CZTI detection
  62. GRB 260523B: GECAM-B observation
  63. GRB 260522A: Fermi GBM Observation
  64. GRB 260522A: Fermi-LAT detection
  65. GRB 260519C: SVOM/GRM observation
  66. GRB 260520B: SVOM/GRM observation
  67. GRB 260411B: TERI Gamma-ray detection
  68. GRB 260407A: TERI Gamma-ray detection
  69. GRB 260307A: TERI Gamma-ray detection
  70. GRB 260225D: TERI Gamma-ray detection
  71. GRB 251118A: TERI Gamma-ray detection
  72. GRB 251113A: TERI Gamma-ray detection
  73. GRB 260428A: TERI Gamma-ray detection
  74. Konus-Wind detection of GRB 260519C
  75. GRB 260509A: SVOM/ECLAIRs refined analysis
  76. Konus-Wind detection of GRB 260518A
  77. GRB 260518A: AstroSat CZTI detection of a long burst
  78. GRB 260516D: SVOM/ECLAIRs refined analysis
  79. GRB 260515A: SVOM/ECLAIRs refined analysis
  80. GRB 260516D: GOTO optical counterpart detection
  81. GRB 260515A: further Liverpool Telescope observations
  82. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  83. GRB 260516D: GROWTH-India Telescope optical detection
  84. GRB 260516D: SVOM possible detection of a burst
  85. Konus-Wind detection of GRB 260515A
  86. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  87. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  88. EP260514a: TRT optical counterpart candidate
  89. EP260514a: COLIBRÍ optical upper limits
  90. GRB 260515A: SVOM/VT optical candidate from VHF data
  91. GRB 260515A: SVOM detection of a burst
  92. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  93. Konus-Wind detection of GRB 260512A
  94. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  95. GRB 260511B: Mephisto multi-band optical followup
  96. GRB 260512A: AstroSat CZTI detection
  97. The EP-WXT trigger 01709262077 is likely a flaring star
  98. EP260507a: Xinglong Schmidt optical counterpart detection
  99. Konus-Wind detection of GRB 260511B
  100. EP260512a: COLIBRÍ optical upper limits

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