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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"

23574 results found.

  1. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  2. EP260623a: OSIRIS+/GTC redshift z = 0.703
  3. EP260623a: Las Cumbres discovery of the optical counterpart
  4. GRB 260614B: EP-FXT follow-up observation
  5. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  6. GRB 260619A: TRT optical counterpart confirmation
  7. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  8. GRB 260604B: 239Alferov CubeSat detection
  9. GRB 260604A: 239Alferov CubeSat detection
  10. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  11. Konus-Wind detection of GRB 260617A
  12. GRB 260616B: AstroSat CZTI detection
  13. GRB 260619A: Kilonova-Catcher optical upper limit
  14. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  15. EP260618a: COLIBRÍ optical counterpart candidate
  16. IPN triangulation of GRB 260617A (short)
  17. GRB 260506B: cubesat Avion detection
  18. Konus-Wind detection of GRB 260616B/EP260616a
  19. Konus-Wind detection of GRB 260616A
  20. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  21. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  22. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  23. GRB260616C: MAXI/GSC detection
  24. GRB 260616A: Fermi-LAT detection
  25. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  26. GRB 260614A: AstroSat CZTI detection
  27. GRB 260610B / AT 2026owq: Possible re-brightening identified from Pan-STARRS observations
  28. GRB 260604C: GRANDMA late observations with CFHT/MegaCam
  29. GRB 260614B: SVOM/ECLAIRs refined analysis
  30. GRB 260610B: SVOM/GRM observation
  31. GRB 260614B: SVOM/VT optical afterglow confirmation
  32. GRB 260614B: Fermi GBM Observation
  33. GRB 260614A: GECAM-B observation
  34. GRB 260614B: SVOM/VT optical candidate from VHF data
  35. GRB 260614B: SVOM detection of a burst
  36. GRB 260611B: SVOM/GRM detection
  37. The EP-WXT trigger 01709269488 is likely a flaring star
  38. GRB 260610B / AT2026owq: GRANDMA optical observations
  39. GRB 260610B / AT2026owq: further SAO RAS optical observations
  40. EP260605a: COLIBRÍ optical upper limits
  41. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  42. GRB 260610B / AT2026owq: OASDG optical observations
  43. GRB 260610B: IAC-80 Optical observations
  44. GRB 260610B / AT2026owq: SAO RAS optical observations
  45. GRB 260610B: optical counterpart shows spectroscopic redshift of z=0.473
  46. GRB 260610B / AT2026owq: Early ATLAS observations
  47. GRB 260610B: TRT optical observation
  48. GRB 260610B: DDOTI optical observations
  49. GRB 260610B: GOTO optical counterpart candidate
  50. Konus-Wind detection of GRB 260601A
  51. IPN triangulation of GRB 260601A (short/hard)
  52. EP260610a: COLIBRÍ optical upper limits
  53. Konus-Wind detection of GRB 260604C
  54. GRB 260604C: AstroSat CZTI detection
  55. IPN triangulation of GRB 260601B / EP260601a
  56. GRB 260604C: SVOM/ECLAIRs refined analysis
  57. GRB 260608A: SVOM/ECLAIRs refined analysis
  58. Konus-Wind detection of GRB 260607B
  59. GRB 260604C: further SAO RAS optical observations
  60. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  61. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  62. GRB 260608A: SVOM detection of a burst
  63. EP260605a: EP-FXT follow-up observation
  64. GRB 260607A: TRT optical observations
  65. GRB 260604C: GRANDMA further observations
  66. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  67. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  68. GRB 260607B: Fermi GBM Final Localization Correction
  69. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  70. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  71. GRB 260604C: 6 GHz VLA observations
  72. GRB 260604C: SAO RAS optical observations
  73. GRB 260604C: GRANDMA observations
  74. GRB260603A: SVOM/ECLAIRs refined analysis
  75. EP260603a: COLIBRÍ optical upper limit
  76. GRB 260604A: Glowbug gamma-ray detection
  77. GRB 260601B / EP260601a: AstroSat CZTI detection
  78. GRB 260527A/EP260527a: 6 GHz VLA observations
  79. GRB 260604C: GOTO detections of the optical afterglow
  80. GRB 260604C: Correction to GCN 44828
  81. GRB 260604C: Kilonova-Catcher optical afterglow detection
  82. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  83. EP260602d: J-band upper limit with WINTER
  84. EP260602b: J-band upper limit with WINTER
  85. GRB 260604C: LAST detection of optical counterpart candidate
  86. Fermi GRB 260604C: Global MASTER-Net observations report
  87. Fermi GRB 260604C: Global MASTER-Net observations report
  88. SVOM GRB260604.85: Global MASTER-Net observations report
  89. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  90. EP260602a: EP-FXT follow-up observation
  91. EP260603a: Global MASTER-Net observations report
  92. EP260602d: Optical Upper limits with kinder observations
  93. GRB 260603B: Fermi GBM Final Localization
  94. Konus-Wind detection of GRB 260601B/EP260601a
  95. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  96. GRB 260603A: Kilonova-Catcher optical upper limit
  97. GRB 260603A: SVOM/VT optical observations
  98. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  99. Fermi trigger No 802141998: Global MASTER-Net observations report
  100. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate

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