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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"

23601 results found.

  1. GRB 260705C: Glowbug gamma-ray detection of a short burst
  2. GRB 260706A: SVOM/ECLAIRs refined analysis
  3. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  4. GRB 260706A: REM optical/NIR observations
  5. GRB 260706A: LCO optical upper limit
  6. GRB 260705A: SVOM/ECLAIRs refined analysis
  7. GRB 260706A: SVOM detection of a burst
  8. GRB 260706A: Fermi GBM Final Real-time Localization
  9. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  10. IceCube260704A: OHP/T193 optical observations
  11. GRB 260629A: AstroSat CZTI detection
  12. Fermi trigger No 804738310: Global MASTER-Net observations report
  13. Fermi GRB 260703A: Global MASTER-Net observations report
  14. GRB 260623A: Glowbug gamma-ray detection
  15. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  16. Fermi trigger No 804552016: Global MASTER-Net observations report
  17. Fermi GRB 260628A: Global MASTER-Net observations report
  18. EP260626a: COLIBRÍ optical upper limit
  19. Konus-Wind detection of GRB 260623B / EP260623a
  20. EP260623a: TNG NIR afterglow detection
  21. Konus-Wind detection of GRB 260618B
  22. EP260623a: WINTER J-band observations
  23. GRB 260617A: Glowbug gamma-ray detection of a short burst
  24. EP260623a: Optical follow-up observations with Kinder
  25. EP260623a: TRT optical observations
  26. EP260623a: REM optical/NIR afterglow detection
  27. EP 260623a: COLIBRÍ optical observations
  28. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  29. EP260623a: OSIRIS+/GTC redshift z = 0.703
  30. EP260623a: Las Cumbres discovery of the optical counterpart
  31. GRB 260614B: EP-FXT follow-up observation
  32. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  33. GRB 260619A: TRT optical counterpart confirmation
  34. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  35. GRB 260604B: 239Alferov CubeSat detection
  36. GRB 260604A: 239Alferov CubeSat detection
  37. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  38. Konus-Wind detection of GRB 260617A
  39. GRB 260616B: AstroSat CZTI detection
  40. GRB 260619A: Kilonova-Catcher optical upper limit
  41. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  42. EP260618a: COLIBRÍ optical counterpart candidate
  43. IPN triangulation of GRB 260617A (short)
  44. GRB 260506B: cubesat Avion detection
  45. Konus-Wind detection of GRB 260616B/EP260616a
  46. Konus-Wind detection of GRB 260616A
  47. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  48. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  49. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  50. GRB260616C: MAXI/GSC detection
  51. GRB 260616A: Fermi-LAT detection
  52. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  53. GRB 260614A: AstroSat CZTI detection
  54. GRB 260610B / AT 2026owq: Possible re-brightening identified from Pan-STARRS observations
  55. GRB 260604C: GRANDMA late observations with CFHT/MegaCam
  56. GRB 260614B: SVOM/ECLAIRs refined analysis
  57. GRB 260610B: SVOM/GRM observation
  58. GRB 260614B: SVOM/VT optical afterglow confirmation
  59. GRB 260614B: Fermi GBM Observation
  60. GRB 260614A: GECAM-B observation
  61. GRB 260614B: SVOM/VT optical candidate from VHF data
  62. GRB 260614B: SVOM detection of a burst
  63. GRB 260611B: SVOM/GRM detection
  64. The EP-WXT trigger 01709269488 is likely a flaring star
  65. GRB 260610B / AT2026owq: GRANDMA optical observations
  66. GRB 260610B / AT2026owq: further SAO RAS optical observations
  67. EP260605a: COLIBRÍ optical upper limits
  68. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  69. GRB 260610B / AT2026owq: OASDG optical observations
  70. GRB 260610B: IAC-80 Optical observations
  71. GRB 260610B / AT2026owq: SAO RAS optical observations
  72. GRB 260610B: optical counterpart shows spectroscopic redshift of z=0.473
  73. GRB 260610B / AT2026owq: Early ATLAS observations
  74. GRB 260610B: TRT optical observation
  75. GRB 260610B: DDOTI optical observations
  76. GRB 260610B: GOTO optical counterpart candidate
  77. Konus-Wind detection of GRB 260601A
  78. IPN triangulation of GRB 260601A (short/hard)
  79. EP260610a: COLIBRÍ optical upper limits
  80. Konus-Wind detection of GRB 260604C
  81. GRB 260604C: AstroSat CZTI detection
  82. IPN triangulation of GRB 260601B / EP260601a
  83. GRB 260604C: SVOM/ECLAIRs refined analysis
  84. GRB 260608A: SVOM/ECLAIRs refined analysis
  85. Konus-Wind detection of GRB 260607B
  86. GRB 260604C: further SAO RAS optical observations
  87. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  88. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  89. GRB 260608A: SVOM detection of a burst
  90. EP260605a: EP-FXT follow-up observation
  91. GRB 260607A: TRT optical observations
  92. GRB 260604C: GRANDMA further observations
  93. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  94. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  95. GRB 260607B: Fermi GBM Final Localization Correction
  96. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  97. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  98. GRB 260604C: 6 GHz VLA observations
  99. GRB 260604C: SAO RAS optical observations
  100. GRB 260604C: GRANDMA observations

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