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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"

39057 results found.

  1. GRB 260903A: NOT optical observations and afterglow fading
  2. SVOM GRB260903A: Global MASTER-Net observations report
  3. GRB 260903A: LCO optical observations
  4. GRB 260903A: SVOM/VT optical candidate
  5. GRB 260903A: Retraction of optical counterpart of GCN 45501
  6. GRB 260831A: GECAM-B observation
  7. GRB 260903A: LCO optical counterpart detection
  8. GRB 260827A: Insight-HXMT/HE detection
  9. GRB 260903A: SVOM detection of a soft faint burst
  10. Konus-Wind detection of GRB 260829A
  11. GRB 260829A: SVOM/GRM observation
  12. GRB 260818A: ATCA detection of a candidate radio counterpart
  13. EP260901a: Global MASTER-Net observations report
  14. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  15. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  16. NuSTAR Transient 260828: LCO Optical Upper Limits
  17. SVOM trigger sb26083106 is not a GRB
  18. GRB 260829A: AstroSat CZTI detection
  19. GRB 260831B: EP-FXT follow-up observation
  20. GRB 260830A: NuSTAR detection of prompt emission
  21. GRB 260831B: LCO optical upper limits
  22. EP260830a: Global MASTER-Net observations report
  23. GRB 260827A: SVOM/GRM observation
  24. GRB 260831B: SVOM detection of a possible burst
  25. IPN triangulation of GRB 260829A
  26. GRB 260827A: Glowbug gamma-ray detection
  27. GRB 260831A: Fermi GBM Final Real-time Localization
  28. GRB 260829A: GECAM-B observation of a long burst
  29. GRB 260825A: SVOM/GRM observation of a long burst
  30. GRB 260825A: GECAM-B observation
  31. GRB 260829A: Fermi GBM Detection
  32. GRB 260825A: AstroSat CZTI detection
  33. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  34. GRB 260829A: Fermi GBM Final Real-time Localization
  35. Fermi GBM trigger 809666623/260829141 is not a GRB
  36. GRB 260818B: Further EP-FXT observation
  37. GRB 260818B: VLT optical and nIR observations
  38. GRB 260818B: TNG NIR observations
  39. MAXI GRB260827.40: Global MASTER-Net observations report
  40. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  41. GRB 260827A: Fermi GBM Final Real-time Localization
  42. GRB 260818B: 6 GHz VLA observations
  43. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  44. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  45. GRB 260808B: SAO RAS observations of the optical rebrightening
  46. EP260822a: Global MASTER-Net observations report
  47. EP Alert 260820.31: Global MASTER-Net observations report
  48. GRB 260807A: EP-FXT follow-up observations
  49. GRB 260822A: SVOM/ECLAIRs refined analysis
  50. GRB 260809A: SVOM/ECLAIRs refined analysis
  51. GRB 260822A: SVOM/VT optical upper limits
  52. IceCube Alert 260825A: Global MASTER-Net observations report
  53. GRB 260825A: Fermi GBM Final Real-time Localization
  54. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  55. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  56. GRB 260822A: EP/FXT follow-up observations
  57. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  58. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  59. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  60. GRB 260822A: GOTO optical counterpart detection
  61. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  62. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  63. EP260822a: Einstein Probe detection of a fast X-ray transient
  64. GRB 260822A: LCO optical upper limits
  65. The EP-WXT trigger 01709287395 is likely a flaring star
  66. GRB260822B: Fermi GBM Final Localization
  67. GRB 260822A: GROWTH-India Telescope Upper Limits
  68. GRB 260822A: GOTO optical upper limit
  69. GRB 260822A: SVOM detection of a short burst
  70. GRB 260818B: VLA radio observations
  71. GRB 260818B: SVOM/C-GFT optical upper limit
  72. IceCube Alert 260821A: Global MASTER-Net observations report
  73. GRB 260820A: Insight-HXMT/HE detection
  74. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  75. GRB 260818B: SVOM/GRM observation
  76. GRB260820A: Fermi GBM Final Real-Time Localization
  77. GRB 260818B: Insight-HXMT detection
  78. GRB 260818B: EP-FXT follow-up observation
  79. GRB 260818A: J-band observations with WINTER
  80. GRB 260818B: SVOM/ECLAIRs refined analysis
  81. GRB 260818A: SVOM/ECLAIRs refined analysis
  82. GRB 260818B: NOT optical upper limits
  83. GRB 260810A: SVOM/GRM observation
  84. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  85. GRB260818A: EP-FXT follow-up observation
  86. GRB 260818B: LCO optical upper limits
  87. GRB 260818B: SVOM detection of a short burst
  88. SVOM trigger sb26081806 is not a GRB
  89. EP260806a: SAO RAS multicolor optical observations
  90. GRB 260818A: LCO optical upper limits
  91. EP260812a: AbAO optical upper limit
  92. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  93. GRB 260810A: Insight-HXMT/HE detection
  94. GRB 260818A: SVOM possible detection of a long and faint GRB
  95. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  96. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  97. GRB 260808B: Liverpool Telescope further optical observations
  98. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  99. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  100. GRB 260813A: Fermi GBM Final Real-time Localization

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