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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"

32510 results found.

  1. GRB 260307B: Mephisto optical upper limits
  2. GRB 260307B: possible NOT optical counterpart
  3. GRB 260307B: SVOM/VT upper limit with X band data analysis
  4. Fermi GRB 260307A: Global MASTER-Net observations report
  5. GRB260307B: GROWTH-India Telescope optical upper limit
  6. GRB 260307B: SVOM/VT optical candidate
  7. GRB 260307B: SVOM/C-GFT upper limit
  8. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  9. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  10. GRB 260207A: TESS Detection and Possible VLA Counterpart
  11. EP260302a: SVOM/VT optical observation
  12. EP260306a: Gemini-North redshift z = 4.773
  13. EP260306a: SVOM/VT optical observation
  14. EP260302a: Gemini-South redshift z = 1.535
  15. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  16. EP260306a: Einstein Probe detection of an X-ray transient
  17. EP260302a: Optical afterglow rebrightening
  18. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  19. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  20. GRB 260303A: 1.3m DFOT optical upper limit
  21. EP260214b: ATCA 6 GHz observations
  22. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  23. GRB 260303A: SVOM/ECLAIRs refined analysis
  24. Fermi GRB 260305A: Global MASTER-Net observations report
  25. GRB 260303B: AstroSat CZTI detection
  26. GRB 260303A: SVOM/VT optical observations
  27. GRB 260303A: J-band observations with WINTER
  28. GRB 260303B: NuSTAR detection of prompt emission
  29. EP260302a: Global MASTER-Net observations report
  30. Fermi GRB 260303B: Global MASTER-Net observations report
  31. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  32. GRB 260228A: SVOM/ECLAIRs refined analysis
  33. GRB 260225A: SVOM/ECLAIRs refined analysis
  34. EP260302a: analysis of the follow-up EP-FXT observation
  35. EP260227a: Gemini-South optical observations
  36. EP260302a: LCO observations
  37. EP260302a: BOOTES-7 optical counterpart detection at early times
  38. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  39. GRB 260228A: EP-FXT follow-up observation
  40. GRB 251130B: TERI Gamma-ray detection
  41. GRB 260208A: TERI Gamma-ray detection
  42. EP260227a: Mondy optical observations
  43. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  44. EP260227a: Mephisto optical detection
  45. GRID detection of GRB 260225D
  46. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  47. EP260227a: further LCO observations
  48. EP260227a: SVOM/VT optical observation
  49. GRB 260228A: SVOM/VT optical upper limits
  50. GRB 260225D: SVOM/GRM observation
  51. EP260227A: 3.6m DOT optical afterglow detection
  52. GRB 260225B: SVOM/GRM observation
  53. EP260227a: FTW optical and NIR observations
  54. EP260227a: Liverpool Telescope optical observations
  55. EP260227a: LCOGT Optical Observations
  56. GRB 260226A: Asiago r-band upper limit
  57. EP260227a: Thai National Telescope observations
  58. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  59. EP260227a: Liverpool Telescope observations
  60. EP260227a: COLIBRÍ optical observations
  61. EP260227a: NOT optical observations
  62. GRB 260225A: SVOM/VT optical continued observations and upper limit
  63. GRID detection of GRB 260223A
  64. EP260227a: Global MASTER-Net observations report
  65. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  66. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  67. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  68. Konus-Wind detection of GRB 260226A
  69. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  70. EP260214a: VLT/FORS2 optical observations
  71. GRB 260225A: WINTER J-band upper limit
  72. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  73. GRB 260226A: COLIBRÍ optical upper limits
  74. GRB 260226A: LCOGT Optical Upper Limit
  75. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  76. GRB 260226A: Glowbug gamma-ray detection
  77. GRB 260226A: NuSTAR detection of bright prompt emission
  78. GRB 260226A : GROWTH-India Telescope optical observations
  79. GRB 260226A: LAST optical upper limit
  80. GRB 260226A: Fermi GBM observation
  81. GRB 260226A: Fermi-LAT refined analysis
  82. Fermi GRB 260226A: Global MASTER-Net observations report
  83. GRB 260226A: AstroSat CZTI detection of bright long burst
  84. EP260214a: VLA 6 GHz detection
  85. GRB 260226A: Fermi-LAT detection of a bright burst
  86. EP260224a: LCO optical upper limits
  87. GRB260225A: SVOM/ECLAIRs refined position
  88. GRB 260225A: EP-FXT follow-up observation
  89. GRB 260225A: SVOM/VT optical observation
  90. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  91. GRB 260223A: Fermi GBM Observation
  92. GRB 260225A: SVOM/VT optical upper limits
  93. EP260126a: VLA 6 GHz detection
  94. EP260223a: Liverpool Telescope upper limits
  95. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  96. EP 260225.148: COLIBRÍ Confirmation of flaring star
  97. EP260223a: Xinglong optical upper limit
  98. GRB 260223A: Glowbug gamma-ray detection
  99. EP260213a: Mephisto optical upper limits
  100. EP260223a: EP-FXT follow-up observation

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