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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

27029 results found.

  1. EP260806a: NUTTELA-TAO optical observations
  2. The EP-WXT trigger 01709281429 is likely a flaring star
  3. EP260812a: AZT-22 optical upper limit
  4. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  5. EP260806a: WFST optical observations
  6. The EP-WXT trigger 01709280562 is likely a flaring star
  7. EP260812b: Optical upper limit with Kinder
  8. The EP-WXT trigger 01709279838 is likely a flaring star
  9. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  10. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  11. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  12. GRB 260813A: Fermi GBM Final Real-time Localization
  13. EP260812a: NOT and Liverpool Telescope upper limits:
  14. EP260812b: Liverpool Telescope observations
  15. EP260812b: GOTO detection of the optical counterpart
  16. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  17. EP260812a: SVOM/C-GFT optical upper limit
  18. EP260812b: SVOM/VT optical observation
  19. GRB 260808A: SVOM/GRM observation
  20. EP260812b: Einstein Probe detection of an X-ray transient
  21. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  22. Fermi GBM Sub-Threshold Detection of GRB 260809A
  23. GRB 260810A: Glowbug gamma-ray detection
  24. GRB 260810A: AstroSat CZTI detection of a long burst
  25. EP260812a: Einstein Probe detection of an X-ray transient
  26. GRB 260809A: SAO RAS optical observations
  27. GRB 260808B: SAO RAS optical observations
  28. GRB 260808B: SVOM/VT optical re-brightening at day 3
  29. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  30. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  31. GRB 260808A: GECAM-B observation
  32. GRB 260807A: SVOM/ECLAIRs refined analysis
  33. EP260806a: MAO/AZT-22 optical observations
  34. GRB260808B: MAO/AZT-22 optical observations
  35. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  36. GRB 260809A: J-band upper limit with WINTER
  37. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  38. GRB 260806A: Glowbug gamma-ray detection
  39. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  40. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  41. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  42. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  43. The EP-WXT trigger 01709278015 is likely a flaring star
  44. GRB 260809A: NOT optical observations
  45. GRB260809A: MAO/AZT-22 optical observations
  46. GRB 260809A: SVOM/VT optical counterpart
  47. EP260809a: J-band upper limit with WINTER
  48. GRB 260808B: J-band upper limit with WINTER
  49. GRB 260808B: SVOM/ECLAIRs refined analysis
  50. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  51. GRB 260809A: SVOM detection of a faint burst
  52. GRB 260808B: NOT optical observations
  53. GRB 260808B: LCO optical observations
  54. GRB 260808A: NuSTAR detection of prompt emission
  55. EP260809a: COLIBRÍ optical observations
  56. EP260809a: LCO optical observation
  57. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  58. EP260809a: Einstein Probe detection of an X-ray transient
  59. GRB 260808B: SVOM/VT optical afterglow confirmation
  60. GRB 260808C: Fermi GBM Final Real-time Localization
  61. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  62. GRB 260808B: SVOM/VT optical candidate from VHF data
  63. GRB 260808B: SVOM detection of a faint burst
  64. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  65. GRB 260808A: Fermi GBM Final Real-time Localization
  66. EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
  67. IceCube-260805A: One candidate from the Zwicky Transient Facility
  68. GRB 260807A: SVOM possible detection of a faint burst
  69. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  70. EP260806a: COLIBRÍ optical observations
  71. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  72. EP260806a: SVOM/VT optical observation
  73. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  74. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  75. EP260806a: LCO likely optical counterpart
  76. EP260806a: Einstein Probe detection of an X-ray transient
  77. GRB 260715A: cubesat Avion detection
  78. GRB 260709A: cubesat Avion detection
  79. GRB 260708A: cubesat Avion detection
  80. SN 2026stf / GRB 260708A: ATLAS forced photometry
  81. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
  82. GRB 260730B: Glowbug gamma-ray detection
  83. GRB 260805C: Glowbug gamma-ray detection
  84. GRB 260805B: Glowbug gamma-ray detection
  85. GRB 260805B: Fermi GBM Final Localization
  86. GRB 260804A: Glowbug gamma-ray detection
  87. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  88. GRB 260805A: Fermi GBM Final Localization
  89. AT 2026wki: EP/FXT follow-up observations
  90. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  91. GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
  92. GRB 260804A: Fermi GBM Final Real-time Localization
  93. GRB 260803A: Fermi GBM Final Real-time Localization
  94. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  95. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  96. GRB 260802A: SVOM/VT optical upper limits from VHF data
  97. GRB 260802A: LCO optical upper limits
  98. GRB 260802B: Fermi GBM Final Localization
  99. The EP-WXT trigger 01709277420 is likely a flaring star
  100. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst

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