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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"

26483 results found.

  1. GRB 260809A: SVOM/VT optical counterpart
  2. EP260809a: J-band upper limit with WINTER
  3. GRB 260808B: J-band upper limit with WINTER
  4. GRB 260808B: SVOM/ECLAIRs refined analysis
  5. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  6. GRB 260809A: SVOM detection of a faint burst
  7. GRB 260808B: Liverpool Telescope optical observations
  8. GRB 260808B: NOT optical observations
  9. GRB 260808B: LCO optical observations
  10. GRB 260808A: NuSTAR detection of prompt emission
  11. EP260809a: COLIBRÍ optical observations
  12. EP260809a: LCO optical observation
  13. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  14. EP260809a: Einstein Probe detection of an X-ray transient
  15. GRB 260808B: SVOM/VT optical afterglow confirmation
  16. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  17. GRB 260808B: SVOM/VT optical candidate from VHF data
  18. GRB 260808B: SVOM detection of a faint burst
  19. EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
  20. IceCube-260805A: One candidate from the Zwicky Transient Facility
  21. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  22. GRB 260807A: SVOM possible detection of a faint burst
  23. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  24. EP260806a: COLIBRÍ optical observations
  25. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  26. EP260806a: SVOM/VT optical observation
  27. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  28. EP260806a: OSIRIS+/GTC redshift z=0.089
  29. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  30. EP260806a: LCO likely optical counterpart
  31. EP260806a: Einstein Probe detection of an X-ray transient
  32. GRB 260715A: cubesat Avion detection
  33. GRB 260709A: cubesat Avion detection
  34. GRB 260708A: cubesat Avion detection
  35. SN 2026stf / GRB 260708A: ATLAS forced photometry
  36. IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
  37. GRB 260730B: Glowbug gamma-ray detection
  38. GRB 260805C: Glowbug gamma-ray detection
  39. GRB 260805B: Glowbug gamma-ray detection
  40. GRB 260804A: Glowbug gamma-ray detection
  41. GRB 260805A: Fermi GBM Final Localization
  42. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  43. GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
  44. GRB 260708A: LCO further optical observations show supernova features
  45. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  46. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  47. GRB 260802A: SVOM/VT optical upper limits from VHF data
  48. GRB 260802A: LCO optical upper limits
  49. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  50. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  51. GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
  52. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  53. GRB 260731A: AstroSat CZTI detection of a long burst
  54. GRB 260730B: AstroSat CZTI detection
  55. EP260731a: COLIBRÍ optical upper limit
  56. EP260731a: NOT optical upper limit
  57. GRB 260730B: NuSTAR detection of prompt emission
  58. EP260731a: Einstein Probe detection of an X-ray transient
  59. GRB 260727A: SVOM/ECLAIRs refined analysis
  60. GRB 260726A: SVOM/ECLAIRs refined analysis
  61. EP260728a: COLIBRÍ optical upper limit
  62. EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
  63. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  64. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
  65. EP260729a: Einstein Probe detection of an X-ray transient
  66. EP260727a: SAO RAS optical observations
  67. GRB 260727A: AbAO and SAO RAS optical observations
  68. EP260728a: EP-FXT follow-up observation
  69. GRB 260726A: EP-FXT follow-up observations
  70. EP260728a: Einstein Probe detection of a fast X-ray transient
  71. GRB 260727A: SVOM/GRM observation
  72. GRB 260726A: Fermi GBM Observation
  73. EP260727a: 1.5m OSN optical counterpart detection
  74. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  75. Konus-Wind detection of GRB 260727A
  76. GRB 260726A: Liverpool Telescope optical observations
  77. GRB 260727A: Liverpool Telescope optical upper limits
  78. EP260727a: Liverpool Telescope confirmation of optical counterpart
  79. EP260727a: NUTTELA-TAO Early Optical Limits
  80. GRB 260727A: EP/FXT follow-up observations
  81. EP260727a: Einstein Probe detection of an X-ray transient
  82. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  83. GRB 260727A: Glowbug gamma-ray detection
  84. GRB 260726A: J-band upper limit with WINTER
  85. GRB 260727A: J-band upper limit with WINTER
  86. GRB 260726A: SVOM/VT optical candidate
  87. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  88. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  89. EP260723a: SVOM/ECLAIRs Upper Limit
  90. GRB 260727A: GOTO early optical upper limit
  91. GRB 260727A: AstroSat CZTI detection
  92. GRB 260727A: Kilonova-Catcher optical upper limit
  93. GRB 260727A: LCO optical upper limits
  94. GRB 260727A: SVOM detection of a bright long burst
  95. GRB 260726A: SVOM detection of a burst
  96. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  97. EP260723a: further EP-FXT follow-up observation
  98. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  99. EP260725a: EP-WXT detection of an X-ray transient
  100. GRB 260616A: cubesat Avion detection

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