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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"

3746 results found.

  1. GRB 260916A: MAXI/GSC detection
  2. EP Alert 260914.53: Global MASTER-Net observations report
  3. SVOM GRB260914.47: Global MASTER-Net observations report
  4. GRB 260907A: SVOM/GRM observation
  5. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  6. Fermi GRB 260907A: Global MASTER-Net observations report
  7. GRB 260907A: Fermi GBM Final Real-time Localization
  8. EP Alert 260903.62: Global MASTER-Net observations report
  9. SVOM GRB260903A: Global MASTER-Net observations report
  10. Konus-Wind detection of GRB 260829A
  11. GRB 260829A: SVOM/GRM observation
  12. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  13. NuSTAR 260828: a 1100s hard X-ray transient
  14. EP260727a: ATCA 10 GHz detection
  15. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  16. GRB 260818B: TNG NIR observations
  17. MAXI GRB260827.40: Global MASTER-Net observations report
  18. EP Alert 260820.31: Global MASTER-Net observations report
  19. IceCube Alert 260825A: Global MASTER-Net observations report
  20. GRB 260822A: GOTO optical counterpart detection
  21. GRB260822B: Fermi GBM Final Localization
  22. GRB 260818B: VLA radio observations
  23. EP260806a: SAO RAS multicolor optical observations
  24. EP260812a: SVOM/C-GFT optical upper limit
  25. GRB 260808B: SVOM/VT optical afterglow confirmation
  26. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  27. GRB 260808B: SVOM/VT optical candidate from VHF data
  28. EP260806a: Einstein Probe detection of an X-ray transient
  29. SN 2026stf / GRB 260708A: ATLAS forced photometry
  30. Fermi GRB 260805A: Global MASTER-Net observations report
  31. GRB 260803A: Fermi GBM Final Real-time Localization
  32. Fermi GRB 260802B: Global MASTER-Net observations report
  33. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  34. GRB260730A: Fermi GBM Final Localization
  35. EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
  36. GRB 260727A: AbAO and SAO RAS optical observations
  37. EP260728a: EP-FXT follow-up observation
  38. EP260727a: 1.5m OSN optical counterpart detection
  39. GRB 260726A: Liverpool Telescope optical observations
  40. GRB 260727A: Liverpool Telescope optical upper limits
  41. EP260727a: Liverpool Telescope confirmation of optical counterpart
  42. GRB 260728A: Fermi GBM Final Localization
  43. GRB 260726A: SVOM/VT optical candidate
  44. EP260723a: SVOM/VT optical observation
  45. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  46. Fermi GRB 260718A: Global MASTER-Net observations report
  47. GRB260708B: MAXI/GSC detection
  48. Fermi GBM Sub-Threshold Detection of GRB 260705A
  49. GRB 260705A: SVOM detection of a burst
  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 GRB 260628A: Global MASTER-Net observations report
  53. GRB 260628A: Fermi GBM Final Real-time Localization
  54. Konus-Wind detection of GRB 260623B / EP260623a
  55. IPN triangulation of GRB 260605A
  56. GRB 260604A: 239Alferov CubeSat detection
  57. GRB 260506B: cubesat Avion detection
  58. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  59. GRB 260614A: AstroSat CZTI detection
  60. The EP-WXT trigger 01709269893 is likely a flaring star
  61. The EP-WXT trigger 01709269488 is likely a flaring star
  62. GRB 260610B / AT2026owq: SVOM/VT optical observations
  63. GRB 260515A: SOAR optical observations
  64. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  65. GRB 260604C: GOTO detections of the optical afterglow
  66. Fermi GRB 260604C: Global MASTER-Net observations report
  67. Fermi GRB 260604C: Global MASTER-Net observations report
  68. EP260602d: Optical Upper limits with kinder observations
  69. Fermi GRB 260602B: Global MASTER-Net observations report
  70. Fermi GRB 260602B: Global MASTER-Net observations report
  71. Fermi GRB 260601A: Global MASTER-Net observations report
  72. Fermi trigger No 801900520: Global MASTER-Net observations report
  73. GRB 260527A / EP260527a: VLA radio detection
  74. Fermi GRB 260529A: Global MASTER-Net observations report
  75. EP260527a: COLIBRÍ optical detection
  76. Fermi trigger No 801580882: Global MASTER-Net observations report
  77. Fermi GRB 260525A: Global MASTER-Net observations report
  78. GRB 260523B: AstroSat CZTI detection
  79. Fermi GRB 260522A: Global MASTER-Net observations report
  80. Fermi GRB 260516C: Global MASTER-Net observations report
  81. GRB 260516D: SVOM possible detection of a burst
  82. GRID detection of GRB 260507A
  83. SVOM GRB 260515A: Global MASTER-Net observations report
  84. Fermi GRB 260514A: Global MASTER-Net observations report
  85. Fermi GRB 260512A: Global MASTER-Net observations report
  86. GRB 260506A: Glowbug gamma-ray detection of a short burst
  87. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  88. Fermi GRB 260510A: Global MASTER-Net observations report
  89. GRB 260507A: Fermi GBM Final Real-time Localization
  90. GRB 260506A: Fermi GBM Final Real-time Localization
  91. Fermi GRB 260504A: Global MASTER-Net observations report
  92. Fermi GRB 260429A: Global MASTER-Net observations report
  93. GRB 260428A: AstroSat CZTI detection
  94. Fermi GRB 260428A: Global MASTER-Net observations report
  95. GRB 260424B: COLIBRÍ optical upper limit
  96. GRB 260428A: Fermi GBM Final Real-time Localization
  97. GRB 260401A: cubesat Avion detection
  98. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  99. EP260416a: Mondy optical observations
  100. GRB 260419A: AstroSat CZTI detection

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