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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"

20901 results found.

  1. IceCube Alert 260722A: Global MASTER-Net observations report
  2. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  3. GRB 260705A: Retraction of optical counterpart
  4. Fermi trigger No 806104130: Global MASTER-Net observations report
  5. Fermi GRB 260718A: Global MASTER-Net observations report
  6. GRB 260718A : GRANDMA and KNC upper limits
  7. GRB 260718A: SVOM/VT optical upper limits
  8. GRB 260718A: SVOM detection of a burst
  9. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  10. GRB 260714B: COLIBRÍ optical counterpart candidate
  11. SVOM sb26071506: Global MASTER-Net observations report
  12. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  13. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  14. GRB 260706A: ATCA detection of possible radio counterpart
  15. GRB 260705A: ATCA radio observations
  16. GRB 260619A: SVOM/VT continuous optical observations
  17. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  18. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  19. EP260623a: KAIT optical observations
  20. GRB 260708A: GRANDMA Optical Observations
  21. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  22. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  23. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  24. GRB 260708A: LCO optical observations
  25. EP260711a: Einstein Probe detection of an X-ray transient
  26. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  27. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  28. GRB 260704A: SVOM/ECLAIRs refined analysis
  29. GRB 260706A : GRANDMA Upper limits
  30. GRB 260708A: Kilonova-Catcher optical afterglow detection
  31. IceCube-260708A: One candidate from the Zwicky Transient Facility
  32. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  33. IceCube Alert 260709A: Global MASTER-Net observations report
  34. LAT GRB260708.42: Global MASTER-Net observations report
  35. GRB 260706A: SVOM/VT optical upper limits
  36. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  37. GRB 260706A: SVOM/ECLAIRs refined analysis
  38. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  39. GRB 260706A: REM optical/NIR observations
  40. IceCube-260704A: No candidates from the Zwicky Transient Facility
  41. GRB 260705A: SVOM/ECLAIRs refined analysis
  42. IceCube260704A: OHP/T193 optical observations
  43. GRB 260704A: NOT optical upper limits
  44. EP260703a: EP-WXT detection of a fast X-ray transient
  45. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  46. Fermi trigger No 804738310: Global MASTER-Net observations report
  47. Fermi GRB 260703A: Global MASTER-Net observations report
  48. GRB 260610B: VLA detection
  49. GRB 260614B: ATCA Radio Upper Limits
  50. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  51. Fermi trigger No 804552016: Global MASTER-Net observations report
  52. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  53. Fermi GRB 260628A: Global MASTER-Net observations report
  54. EP260628a: EP-WXT detection of a fast X-ray transient
  55. EP260626a: EP-WXT detection of a fast X-ray transient
  56. EP260623a: FTW optical and NIR observations
  57. GRB 260619A: SVOM/ECLAIRs refined analysis
  58. EP260623a: Liverpool Telescope optical observations
  59. EP260623a: WINTER J-band observations
  60. EP260623a: Optical follow-up observations with Kinder
  61. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  62. EP260623a: SVOM/VT optical observations
  63. EP260623a: TRT optical observations
  64. EP260623a: REM optical/NIR afterglow detection
  65. EP 260623a: COLIBRÍ optical observations
  66. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  67. EP260618a: Liverpool Telescope optical observations
  68. GRB 260619A: NOT optical observations
  69. GRB 260618B: LCO optical observations
  70. EP260618a: JinShan optical observations
  71. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  72. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  73. GRB 260619A: SVOM/VT optical counterpart confirmation
  74. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  75. GRB 260618B: SVOM/VT optical candidate
  76. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  77. EP260618a: OHP/T193 optical observations
  78. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  79. GRB 260619A: Kilonova-Catcher optical upper limit
  80. EP260618a: EP-FXT follow-up observation
  81. EP260618a: COLIBRÍ optical counterpart candidate
  82. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  83. EP260618a: EP-WXT detection of an X-ray transient
  84. GRB 260610B: AbAO optical observations
  85. EP260616a/GRB 260616B: EP-FXT follow-up observation
  86. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  87. GRB260616C: MAXI/GSC detection
  88. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  89. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  90. EP260616a: EP-WXT detection of a fast X-ray transient
  91. GRB 260610B / AT 2026owq: Possible re-brightening identified from Pan-STARRS observations
  92. GRB 260604C: GRANDMA late observations with CFHT/MegaCam
  93. GRB 260614B: SVOM/ECLAIRs refined analysis
  94. GRB 260610B: Terskol optical observations
  95. GRB 260614B: SVOM/VT optical afterglow confirmation
  96. GRB 260610B: ALMA detection
  97. GRB 260610B: further Liverpool Telescope optical observations
  98. GRB 260610B / AT2026owq: GRANDMA optical observations
  99. GRB 260610B / AT2026owq: further SAO RAS optical observations
  100. EP260605a: COLIBRÍ optical upper limits

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