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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"

32484 results found.

  1. GRB 260303A: SVOM/VT optical observations
  2. GRB 260303A: J-band observations with WINTER
  3. GRB 260303B: NuSTAR detection of prompt emission
  4. EP260302a: Global MASTER-Net observations report
  5. Fermi GRB 260303B: Global MASTER-Net observations report
  6. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  7. GRB 260228A: SVOM/ECLAIRs refined analysis
  8. GRB 260225A: SVOM/ECLAIRs refined analysis
  9. EP260302a: analysis of the follow-up EP-FXT observation
  10. EP260227a: Gemini-South optical observations
  11. EP260302a: LCO observations
  12. EP260302a: BOOTES-7 optical counterpart detection at early times
  13. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  14. GRB 260228A: EP-FXT follow-up observation
  15. GRB 251130B: TERI Gamma-ray detection
  16. GRB 260208A: TERI Gamma-ray detection
  17. EP260227a: Mondy optical observations
  18. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  19. EP260227a: Mephisto optical detection
  20. GRID detection of GRB 260225D
  21. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  22. EP260227a: further LCO observations
  23. EP260227a: SVOM/VT optical observation
  24. GRB 260228A: SVOM/VT optical upper limits
  25. GRB 260225D: SVOM/GRM observation
  26. EP260227A: 3.6m DOT optical afterglow detection
  27. GRB 260225B: SVOM/GRM observation
  28. EP260227a: FTW optical and NIR observations
  29. EP260227a: Liverpool Telescope optical observations
  30. EP260227a: LCOGT Optical Observations
  31. GRB 260226A: Asiago r-band upper limit
  32. EP260227a: Thai National Telescope observations
  33. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  34. EP260227a: Liverpool Telescope observations
  35. EP260227a: COLIBRÍ optical observations
  36. EP260227a: NOT optical observations
  37. GRB 260225A: SVOM/VT optical continued observations and upper limit
  38. GRID detection of GRB 260223A
  39. EP260227a: Global MASTER-Net observations report
  40. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  41. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  42. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  43. Konus-Wind detection of GRB 260226A
  44. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  45. EP260214a: VLT/FORS2 optical observations
  46. GRB 260225A: WINTER J-band upper limit
  47. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  48. GRB 260226A: COLIBRÍ optical upper limits
  49. GRB 260226A: LCOGT Optical Upper Limit
  50. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  51. GRB 260226A: Glowbug gamma-ray detection
  52. GRB 260226A: NuSTAR detection of bright prompt emission
  53. GRB 260226A : GROWTH-India Telescope optical observations
  54. GRB 260226A: LAST optical upper limit
  55. GRB 260226A: Fermi GBM observation
  56. GRB 260226A: Fermi-LAT refined analysis
  57. Fermi GRB 260226A: Global MASTER-Net observations report
  58. GRB 260226A: AstroSat CZTI detection of bright long burst
  59. EP260214a: VLA 6 GHz detection
  60. GRB 260226A: Fermi-LAT detection of a bright burst
  61. EP260224a: LCO optical upper limits
  62. GRB260225A: SVOM/ECLAIRs refined position
  63. GRB 260225A: EP-FXT follow-up observation
  64. GRB 260225A: SVOM/VT optical observation
  65. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  66. GRB 260223A: Fermi GBM Observation
  67. GRB 260225A: SVOM/VT optical upper limits
  68. EP260126a: VLA 6 GHz detection
  69. EP260223a: Liverpool Telescope upper limits
  70. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  71. EP 260225.148: COLIBRÍ Confirmation of flaring star
  72. EP260223a: Xinglong optical upper limit
  73. GRB 260223A: Glowbug gamma-ray detection
  74. EP260213a: Mephisto optical upper limits
  75. EP260223a: EP-FXT follow-up observation
  76. sb26021801: SVOM/VT optical upper limits
  77. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  78. sb26021801: SVOM/C-GFT upper limit
  79. EP260223a: COLIBRÍ optical upper limits
  80. GRB 260223A: SVOM/VT optical observation
  81. GRB 260223A: SVOM/GRM observation
  82. GRB 260223A: COLIBRÍ further optical observations and a brightening
  83. EP260221a: Optical upper limit with Kinder observations
  84. GRB 260223A: COLIBRÍ optical observations
  85. GRB 260223A: DDOTI Optical Candidate
  86. Fermi GRB 260223A: Global MASTER-Net observations report
  87. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  88. EP260221a: COLIBRÍ optical counterpart candidate
  89. EP260221a: Gemini South z-band upper limit
  90. EP260221a: Global MASTER-Net observations report
  91. EP260221a: EP-FXT follow-up observation
  92. Fermi GRB 260221B: Global MASTER-Net observations report
  93. EP260221a: Xinglong optical upper limit
  94. Fermi GRB 260221A: Global MASTER-Net observations report
  95. EP260221a: GOTO optical upper limit
  96. EP260221a: COLIBRÍ optical upper limit
  97. SVOM alert sb26021801: LCO optical upper limit
  98. GRB 260219A: AstroSat CZTI detection
  99. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  100. GRB 260219A: GECAM-B observation of a long burst

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