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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"

32504 results found.

  1. GRB 260307B: SVOM/C-GFT upper limit
  2. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  3. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  4. GRB 260207A: TESS Detection and Possible VLA Counterpart
  5. EP260302a: SVOM/VT optical observation
  6. EP260306a: Gemini-North redshift z = 4.773
  7. EP260306a: SVOM/VT optical observation
  8. EP260302a: Gemini-South redshift z = 1.535
  9. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  10. EP260306a: Einstein Probe detection of an X-ray transient
  11. EP260302a: Optical afterglow rebrightening
  12. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  13. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  14. GRB 260303A: 1.3m DFOT optical upper limit
  15. EP260214b: ATCA 6 GHz observations
  16. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  17. GRB 260303A: SVOM/ECLAIRs refined analysis
  18. Fermi GRB 260305A: Global MASTER-Net observations report
  19. GRB 260303B: AstroSat CZTI detection
  20. GRB 260303A: SVOM/VT optical observations
  21. GRB 260303A: J-band observations with WINTER
  22. GRB 260303B: NuSTAR detection of prompt emission
  23. EP260302a: Global MASTER-Net observations report
  24. Fermi GRB 260303B: Global MASTER-Net observations report
  25. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  26. GRB 260228A: SVOM/ECLAIRs refined analysis
  27. GRB 260225A: SVOM/ECLAIRs refined analysis
  28. EP260302a: analysis of the follow-up EP-FXT observation
  29. EP260227a: Gemini-South optical observations
  30. EP260302a: LCO observations
  31. EP260302a: BOOTES-7 optical counterpart detection at early times
  32. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  33. GRB 260228A: EP-FXT follow-up observation
  34. GRB 251130B: TERI Gamma-ray detection
  35. GRB 260208A: TERI Gamma-ray detection
  36. EP260227a: Mondy optical observations
  37. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  38. EP260227a: Mephisto optical detection
  39. GRID detection of GRB 260225D
  40. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  41. EP260227a: further LCO observations
  42. EP260227a: SVOM/VT optical observation
  43. GRB 260228A: SVOM/VT optical upper limits
  44. GRB 260225D: SVOM/GRM observation
  45. EP260227A: 3.6m DOT optical afterglow detection
  46. GRB 260225B: SVOM/GRM observation
  47. EP260227a: FTW optical and NIR observations
  48. EP260227a: Liverpool Telescope optical observations
  49. EP260227a: LCOGT Optical Observations
  50. GRB 260226A: Asiago r-band upper limit
  51. EP260227a: Thai National Telescope observations
  52. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  53. EP260227a: Liverpool Telescope observations
  54. EP260227a: COLIBRÍ optical observations
  55. EP260227a: NOT optical observations
  56. GRB 260225A: SVOM/VT optical continued observations and upper limit
  57. GRID detection of GRB 260223A
  58. EP260227a: Global MASTER-Net observations report
  59. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  60. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  61. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  62. Konus-Wind detection of GRB 260226A
  63. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  64. EP260214a: VLT/FORS2 optical observations
  65. GRB 260225A: WINTER J-band upper limit
  66. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  67. GRB 260226A: COLIBRÍ optical upper limits
  68. GRB 260226A: LCOGT Optical Upper Limit
  69. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  70. GRB 260226A: Glowbug gamma-ray detection
  71. GRB 260226A: NuSTAR detection of bright prompt emission
  72. GRB 260226A : GROWTH-India Telescope optical observations
  73. GRB 260226A: LAST optical upper limit
  74. GRB 260226A: Fermi GBM observation
  75. GRB 260226A: Fermi-LAT refined analysis
  76. Fermi GRB 260226A: Global MASTER-Net observations report
  77. GRB 260226A: AstroSat CZTI detection of bright long burst
  78. EP260214a: VLA 6 GHz detection
  79. GRB 260226A: Fermi-LAT detection of a bright burst
  80. EP260224a: LCO optical upper limits
  81. GRB260225A: SVOM/ECLAIRs refined position
  82. GRB 260225A: EP-FXT follow-up observation
  83. GRB 260225A: SVOM/VT optical observation
  84. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  85. GRB 260223A: Fermi GBM Observation
  86. GRB 260225A: SVOM/VT optical upper limits
  87. EP260126a: VLA 6 GHz detection
  88. EP260223a: Liverpool Telescope upper limits
  89. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  90. EP 260225.148: COLIBRÍ Confirmation of flaring star
  91. EP260223a: Xinglong optical upper limit
  92. GRB 260223A: Glowbug gamma-ray detection
  93. EP260213a: Mephisto optical upper limits
  94. EP260223a: EP-FXT follow-up observation
  95. sb26021801: SVOM/VT optical upper limits
  96. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  97. sb26021801: SVOM/C-GFT upper limit
  98. EP260223a: COLIBRÍ optical upper limits
  99. GRB 260223A: SVOM/VT optical observation
  100. GRB 260223A: SVOM/GRM observation

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