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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"

28063 results found.

  1. Fermi GBM Sub-Threshold Detection of GRB 260915A
  2. GRB 260915A: SVOM detection of a burst
  3. Fermi GBM Sub-Threshold Detection of GRB 260914A
  4. GRB 260914A: SVOM/VT optical observation from VHF data
  5. GRB 260914A: SVOM detection of a burst
  6. GRB 260818A: Continued ATCA observations
  7. GRB 260913A: SVOM detection of a faint burst
  8. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  9. GRB 260910B: GOTO tentative optical counterpart candidates
  10. GRB 260909A: Swift ToO observations
  11. GRB 260910B: Fermi GBM Final Real-time Localization
  12. GRB 260903A: Swift-XRT observations
  13. EP260806a: VLA+ALMA radio detections
  14. GRB 260909A: OHP/T193 z-band upper limit
  15. GRB 260910A: Fermi GBM Final Real-time Localization
  16. EP260806a: NOEMA detection
  17. EP260623a: NOEMA detections
  18. GRB 260909A: Mondy optical observations and afterglow candidate
  19. GRB 260909A: SVOM detection of a burst
  20. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  21. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  22. GRB 260903A: Swift ToO observations
  23. GRB 260907B: Fermi GBM Final Real-time Localization
  24. GRB 260907A: Fermi GBM Final Real-time Localization
  25. EP260903a: EP-FXT follow-up observation
  26. GRB 260830A: GECAM-B detection of a burst
  27. EP260903a: EP-WXT detection of a fast X-ray transient
  28. GRB 260830A: Insight-HXMT/HE detection
  29. GRB 260903A: OHP/T193 optical afterglow detection
  30. GRB 260903A: NOT optical observations and afterglow fading
  31. NuSTAR Transient 260828: SOAR Optical Upper Limits
  32. GRB 260903A: Retraction of optical counterpart of GCN 45501
  33. GRB 260903A: LCO optical counterpart detection
  34. GRB 260827A: Insight-HXMT/HE detection
  35. GRB 260903A: SVOM detection of a soft faint burst
  36. EP260901a: EP-FXT follow-up observation
  37. Konus-Wind detection of GRB 260829A
  38. GRB 260818A: ATCA detection of a candidate radio counterpart
  39. EP260830a: EP-FXT follow-up observation
  40. NuSTAR Transient 260828: LCO Optical Upper Limits
  41. EP260901a: EP-WXT detection of a fast X-ray transient
  42. GRB 260829A: AstroSat CZTI detection
  43. GRB 260830A: NuSTAR detection of prompt emission
  44. EP260830a: EP-WXT detection of a fast X-ray transient
  45. NuSTAR 260828: a 1100s hard X-ray transient
  46. GRB 260831B: SVOM detection of a possible burst
  47. IPN triangulation of GRB 260829A
  48. GRB 260827A: Glowbug gamma-ray detection
  49. EP260727a: ATCA 10 GHz detection
  50. GRB 260831A: Fermi GBM Final Real-time Localization
  51. GRB 260829A: Fermi GBM Detection
  52. GRB 260825A: AstroSat CZTI detection
  53. GRB 260829A: Fermi GBM Final Real-time Localization
  54. GRB 260818B: VLT optical and nIR observations
  55. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  56. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  57. GRB 260827A: Fermi GBM Final Real-time Localization
  58. GRB 260818B: 6 GHz VLA observations
  59. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  60. GRB 260807A: EP-FXT follow-up observations
  61. GRB 260822A: SVOM/VT optical upper limits
  62. GRB 260825A: Fermi GBM Final Real-time Localization
  63. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  64. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  65. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  66. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  67. EP260822a: EP-FXT non-detection and upper limit
  68. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  69. GRB 260822A: GOTO optical counterpart detection
  70. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  71. EP260822a: Einstein Probe detection of a fast X-ray transient
  72. The EP-WXT trigger 01709287395 is likely a flaring star
  73. GRB260822B: Fermi GBM Final Localization
  74. GRB 260822A: SVOM detection of a short burst
  75. GRB 260818B: SVOM/C-GFT optical upper limit
  76. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  77. GRB 260820A: Insight-HXMT/HE detection
  78. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  79. EP detected a brightening of LMXB 1ES 1735-26.9
  80. GRB260820A: Fermi GBM Final Real-Time Localization
  81. GRB 260818B: Insight-HXMT detection
  82. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  83. GRB 260818B: SVOM detection of a short burst
  84. GRB 260810A: Insight-HXMT/HE detection
  85. GRB 260818A: SVOM possible detection of a long and faint GRB
  86. EP260806a: SVOM/ECLAIRs detection through targeted search
  87. EP260806a: WFST optical observations
  88. EP260812b: Optical upper limit with Kinder
  89. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  90. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  91. GRB 260813A: Fermi GBM Final Real-time Localization
  92. EP260812b: Liverpool Telescope observations
  93. EP260812b: GOTO detection of the optical counterpart
  94. EP260812b: Einstein Probe detection of an X-ray transient
  95. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  96. Fermi GBM Sub-Threshold Detection of GRB 260809A
  97. GRB 260810A: Glowbug gamma-ray detection
  98. GRB 260810A: AstroSat CZTI detection of a long burst
  99. EP260812a: Einstein Probe detection of an X-ray transient
  100. GRB 260808B: SVOM/VT optical re-brightening at day 3

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