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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"

27786 results found.

  1. EP260917b: EP-WXT detection of an X-ray transient
  2. IPN triangulation of GRB 260810A
  3. GRB 260915A: Swift-XRT afterglow detection
  4. EP260917a: Einstein Probe detection of an X-ray transient
  5. GRB 260918A: SVOM detection of a burst
  6. GRB 260917C: Fermi GBM Final Real-time Localization
  7. GRB 260916B: Fermi GBM Detection
  8. GRB 260916B: Fermi GBM Final Localization
  9. GRB 260917A: Glowbug gamma-ray detection
  10. GRB 260917B: SVOM detection of a faint burst
  11. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  12. GRB 260917A: Fermi GBM Final Real-time Localization
  13. IceCube-260916A - IceCube observation of a high-energy neutrino candidate track-like event
  14. GRB 260909A: NOEMA detection
  15. GRB 260909A: Swift-XRT observations
  16. GRB 260916A: MAXI/GSC detection
  17. GRB 260915A: Swift ToO observations
  18. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  19. GRB 260915A: SVOM/C-GFT optical upper limits
  20. GRB 260915A: 10.4m GTC deep optical limits
  21. GRB 260915A: SVOM/VT optical upper limits from VHF data
  22. Fermi GBM Sub-Threshold Detection of GRB 260915A
  23. GRB 260915A: SVOM detection of a burst
  24. Fermi GBM Sub-Threshold Detection of GRB 260914A
  25. GRB 260914A: SVOM detection of a burst
  26. GRB 260818A: Continued ATCA observations
  27. GRB 260913A: SVOM detection of a faint burst
  28. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  29. GRB 260910B: GOTO tentative optical counterpart candidates
  30. GRB 260909A: Swift ToO observations
  31. GRB 260910B: Fermi GBM Final Real-time Localization
  32. GRB 260903A: Swift-XRT observations
  33. EP260806a: VLA+ALMA radio detections
  34. GRB 260910A: Fermi GBM Final Real-time Localization
  35. EP260806a: NOEMA detection
  36. EP260623a: NOEMA detections
  37. GRB 260909A: SVOM detection of a burst
  38. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  39. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  40. GRB 260903A: Swift ToO observations
  41. GRB 260907B: Fermi GBM Final Real-time Localization
  42. GRB 260907A: Fermi GBM Final Real-time Localization
  43. EP260903a: EP-FXT follow-up observation
  44. GRB 260830A: GECAM-B detection of a burst
  45. EP260903a: EP-WXT detection of a fast X-ray transient
  46. GRB 260830A: Insight-HXMT/HE detection
  47. GRB 260903A: OHP/T193 optical afterglow detection
  48. NuSTAR Transient 260828: SOAR Optical Upper Limits
  49. GRB 260903A: Retraction of optical counterpart of GCN 45501
  50. GRB 260903A: LCO optical counterpart detection
  51. GRB 260827A: Insight-HXMT/HE detection
  52. GRB 260903A: SVOM detection of a soft faint burst
  53. EP260901a: EP-FXT follow-up observation
  54. Konus-Wind detection of GRB 260829A
  55. GRB 260818A: ATCA detection of a candidate radio counterpart
  56. EP260830a: EP-FXT follow-up observation
  57. NuSTAR Transient 260828: LCO Optical Upper Limits
  58. EP260901a: EP-WXT detection of a fast X-ray transient
  59. GRB 260829A: AstroSat CZTI detection
  60. GRB 260830A: NuSTAR detection of prompt emission
  61. EP260830a: EP-WXT detection of a fast X-ray transient
  62. NuSTAR 260828: a 1100s hard X-ray transient
  63. GRB 260831B: SVOM detection of a possible burst
  64. IPN triangulation of GRB 260829A
  65. GRB 260827A: Glowbug gamma-ray detection
  66. EP260727a: ATCA 10 GHz detection
  67. GRB 260831A: Fermi GBM Final Real-time Localization
  68. GRB 260829A: Fermi GBM Detection
  69. GRB 260825A: AstroSat CZTI detection
  70. GRB 260829A: Fermi GBM Final Real-time Localization
  71. GRB 260818B: VLT optical and nIR observations
  72. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  73. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  74. GRB 260827A: Fermi GBM Final Real-time Localization
  75. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  76. GRB 260822A: SVOM/VT optical upper limits
  77. GRB 260825A: Fermi GBM Final Real-time Localization
  78. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  79. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  80. EP260822a: EP-FXT non-detection and upper limit
  81. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  82. GRB 260822A: GOTO optical counterpart detection
  83. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  84. EP260822a: Einstein Probe detection of a fast X-ray transient
  85. The EP-WXT trigger 01709287395 is likely a flaring star
  86. GRB260822B: Fermi GBM Final Localization
  87. GRB 260822A: SVOM detection of a short burst
  88. GRB 260818B: SVOM/C-GFT optical upper limit
  89. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  90. GRB 260820A: Insight-HXMT/HE detection
  91. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  92. EP detected a brightening of LMXB 1ES 1735-26.9
  93. GRB260820A: Fermi GBM Final Real-Time Localization
  94. GRB 260818B: Insight-HXMT detection
  95. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  96. GRB 260818B: SVOM detection of a short burst
  97. GRB 260810A: Insight-HXMT/HE detection
  98. GRB 260818A: SVOM possible detection of a long and faint GRB
  99. EP260806a: SVOM/ECLAIRs detection through targeted search
  100. EP260806a: WFST optical observations

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