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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"

31727 results found.

  1. GRB 260310A: Fermi GBM Observation
  2. GRB 260310A: potential optical counterpart
  3. Fermi GRB 260312B: Global MASTER-Net observations report
  4. Fermi GRB 260311B: Global MASTER-Net observations report
  5. GRB 260310B: GECAM-B observation of a burst
  6. Retraction of GCN 43965: GRB is actually solar flare
  7. GRB 260131A/B: radio detection with the VLA
  8. EP260302a: MeerKAT radio counterpart
  9. GRB260307A: GECAM-B observation of a burst
  10. GRB 260308A: SVOM/GRM observation of a short GRB
  11. EP260306a: Mondy optical upper limit
  12. GRB 260310A: AstroSat CZTI detection of a long burst
  13. Fermi GRB 260310B: Global MASTER-Net observations report
  14. Fermi GRB 260310A: Global MASTER-Net observations report
  15. GRB 260307B: SVOM/ECLAIRs refined analysis
  16. GRB 260208A: radio detection with the VLA
  17. GRB 260307A: Glowbug gamma-ray detection
  18. Fermi GBM Sub-Threshold Detection of GRB 260307B
  19. GRB 260307B: Mephisto optical upper limits
  20. GRB 260307B: possible NOT optical counterpart
  21. GRB 260307B: SVOM/VT upper limit with X band data analysis
  22. Fermi GRB 260307A: Global MASTER-Net observations report
  23. GRB260307B: GROWTH-India Telescope optical upper limit
  24. GRB 260307B: SVOM/VT optical candidate
  25. GRB 260307B: SVOM/C-GFT upper limit
  26. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  27. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  28. GRB 260207A: TESS Detection and Possible VLA Counterpart
  29. EP260302a: SVOM/VT optical observation
  30. EP260306a: Gemini-North redshift z = 4.773
  31. EP260306a: SVOM/VT optical observation
  32. EP260302a: Gemini-South redshift z = 1.535
  33. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  34. EP260306a: Einstein Probe detection of an X-ray transient
  35. EP260302a: Optical afterglow rebrightening
  36. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  37. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  38. GRB 260303A: 1.3m DFOT optical upper limit
  39. EP260214b: ATCA 6 GHz observations
  40. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  41. GRB 260303A: SVOM/ECLAIRs refined analysis
  42. Fermi GRB 260305A: Global MASTER-Net observations report
  43. GRB 260303B: AstroSat CZTI detection
  44. GRB 260303A: SVOM/VT optical observations
  45. GRB 260303A: J-band observations with WINTER
  46. GRB 260303B: NuSTAR detection of prompt emission
  47. EP260302a: Global MASTER-Net observations report
  48. Fermi GRB 260303B: Global MASTER-Net observations report
  49. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  50. GRB 260228A: SVOM/ECLAIRs refined analysis
  51. GRB 260225A: SVOM/ECLAIRs refined analysis
  52. EP260302a: analysis of the follow-up EP-FXT observation
  53. EP260227a: Gemini-South optical observations
  54. EP260302a: LCO observations
  55. EP260302a: BOOTES-7 optical counterpart detection at early times
  56. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  57. GRB 260228A: EP-FXT follow-up observation
  58. GRB 251130B: TERI Gamma-ray detection
  59. GRB 260208A: TERI Gamma-ray detection
  60. EP260227a: Mondy optical observations
  61. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  62. EP260227a: Mephisto optical detection
  63. GRID detection of GRB 260225D
  64. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  65. EP260227a: further LCO observations
  66. EP260227a: SVOM/VT optical observation
  67. GRB 260228A: SVOM/VT optical upper limits
  68. GRB 260225D: SVOM/GRM observation
  69. EP260227A: 3.6m DOT optical afterglow detection
  70. GRB 260225B: SVOM/GRM observation
  71. EP260227a: FTW optical and NIR observations
  72. EP260227a: Liverpool Telescope optical observations
  73. EP260227a: LCOGT Optical Observations
  74. GRB 260226A: Asiago r-band upper limit
  75. EP260227a: Thai National Telescope observations
  76. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  77. EP260227a: Liverpool Telescope observations
  78. EP260227a: COLIBRÍ optical observations
  79. EP260227a: NOT optical observations
  80. GRB 260225A: SVOM/VT optical continued observations and upper limit
  81. GRID detection of GRB 260223A
  82. EP260227a: Global MASTER-Net observations report
  83. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  84. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  85. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  86. Konus-Wind detection of GRB 260226A
  87. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  88. EP260214a: VLT/FORS2 optical observations
  89. GRB 260225A: WINTER J-band upper limit
  90. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  91. GRB 260226A: COLIBRÍ optical upper limits
  92. GRB 260226A: LCOGT Optical Upper Limit
  93. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  94. GRB 260226A: Glowbug gamma-ray detection
  95. GRB 260226A: NuSTAR detection of bright prompt emission
  96. GRB 260226A : GROWTH-India Telescope optical observations
  97. GRB 260226A: LAST optical upper limit
  98. GRB 260226A: Fermi GBM observation
  99. GRB 260226A: Fermi-LAT refined analysis
  100. Fermi GRB 260226A: Global MASTER-Net observations report

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