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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"

21787 results found.

  1. GRB 260726A: SVOM detection of a burst
  2. EP260725a: EP-WXT detection of an X-ray transient
  3. GRB 260616A: cubesat Avion detection
  4. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  5. GRB 260602B: cubesat Avion detection
  6. GRB 260601A: cubesat Avion detection
  7. GRB 260718A: SVOM/ECLAIRs refined analysis
  8. EP260723a: SVOM/VT optical observation
  9. EP260723a: COLIBRÍ optical observations
  10. EP260723a: NOT optical conterpart confirmation
  11. EP260723a: Liverpool Telescope likely optical counterpart
  12. EP260723a: EP-WXT detection of a fast X-ray transient
  13. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  14. Konus-Wind detection of GRB 260721A
  15. Konus-Wind detection of GRB 260714B
  16. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  17. GRB 260718A: LCO optical upper limits
  18. GRB 260710A: SVOM/GRM observation
  19. GRB 260718A : GRANDMA and KNC upper limits
  20. GRB 260718A: SVOM/VT optical upper limits
  21. GRB 260718A: SVOM/VT optical upper limits from VHF data
  22. GRB 260718A: SVOM detection of a burst
  23. GRB 260714B: SVOM/GRM observation
  24. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  25. GRB 260714B: COLIBRÍ optical counterpart candidate
  26. sb26071506: SVOM detection of a X-ray transient
  27. EP260703a: SVOM/ECLAIRs Upper Limit
  28. GRB 260714B: AstroSat CZTI detection
  29. GRB 260714B: Fermi-LAT detection
  30. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  31. GRB 260706A: ATCA detection of possible radio counterpart
  32. EP260713a: Einstein Probe detection of an X-ray transient
  33. EP260623a: KAIT optical observations
  34. GRB 260708A: GRANDMA Optical Observations
  35. GRB 260708A: LCO optical observations
  36. EP260711a: Einstein Probe detection of an X-ray transient
  37. GRB 260709A: SVOM/GRM detection
  38. GRB 260709A: GECAM-B observation
  39. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  40. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  41. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  42. GRB 260704A: SVOM/ECLAIRs refined analysis
  43. GRB 260706A : GRANDMA Upper limits
  44. GRB 260708A: Kilonova-Catcher optical afterglow detection
  45. IceCube-260708A: One candidate from the Zwicky Transient Facility
  46. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  47. GRB 260708A: Fermi-LAT detection
  48. GRB 260705B: SVOM/GRM observation
  49. EP260707a (by EP-FXT): NOT optical upper limit
  50. EP260707a is not a real source
  51. EP260707a: LCOGT Optical Upper Limit
  52. EP260707a: TRT optical upper limit
  53. EP260707a: Einstein Probe detection of an X-ray transient
  54. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  55. GRB 260706A: SVOM/ECLAIRs refined analysis
  56. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  57. GRB 260706A: REM optical/NIR observations
  58. GRB 260706A: LCO optical upper limit
  59. GRB 260705A: SVOM/ECLAIRs refined analysis
  60. GRB 260705A: LCO optical upper limits
  61. GRB 260704A: NOT optical upper limits
  62. GRB 260705B: Fermi GBM Final Real-time Localization
  63. GRB 260629A: SVOM/GRM observation of a short burst
  64. GRB 260704A: SVOM detection of a possible GRB
  65. EP260703a: EP-WXT detection of a fast X-ray transient
  66. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  67. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  68. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  69. EP260628a: EP-WXT detection of a fast X-ray transient
  70. EP260626a: further Liverpool Telescope optical upper limits
  71. EP260626a: COLIBRÍ optical upper limit
  72. EP260626a: Liverpool Telescope upper limits
  73. EP260626a: EP-WXT detection of a fast X-ray transient
  74. EP260623a: TNG NIR afterglow detection
  75. GRB 260619A: SVOM/ECLAIRs refined analysis
  76. EP260623a: Liverpool Telescope optical observations
  77. Konus-Wind detection of GRB 260618B
  78. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  79. EP260623a: WINTER J-band observations
  80. EP260623a: Optical follow-up observations with Kinder
  81. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  82. EP260623a: SVOM/VT optical observations
  83. EP260623a: TRT optical observations
  84. EP260623a: REM optical/NIR afterglow detection
  85. EP 260623a: COLIBRÍ optical observations
  86. EP260623a: Las Cumbres discovery of the optical counterpart
  87. EP260623a: Einstein Probe detection of an X-ray transient
  88. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  89. EP260618a: Liverpool Telescope optical observations
  90. GRB 260618B: LCO optical observations
  91. EP260618a: JinShan optical observations
  92. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  93. GRB 260619A: TRT optical counterpart confirmation
  94. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  95. GRB 260604A: 239Alferov CubeSat detection
  96. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  97. Konus-Wind detection of GRB 260617A
  98. GRB 260616B: AstroSat CZTI detection
  99. GRB 260616A: AstroSat CZTI detection
  100. GRB 260616A: SVOM/GRM observation

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