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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"

43587 results found.

  1. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  2. GRB 260225C: Fermi GBM Final Real-time Localization
  3. GRB 260223A: Fermi GBM Observation
  4. GRB 260225A: SVOM/VT optical upper limits
  5. GRB 260225B: Fermi GBM Final Real-time Localization
  6. EP260126a: VLA 6 GHz detection
  7. EP260223a: Liverpool Telescope upper limits
  8. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  9. GRB 260225A: SVOM detection of a burst
  10. EP260224a: Einstein Probe detection of an X-ray transient
  11. EP 260225.148: COLIBRÍ Confirmation of flaring star
  12. EP260223a: Xinglong optical upper limit
  13. The EP-WXT trigger 01709258631 is likely a flaring star
  14. GRB 260223A: Glowbug gamma-ray detection
  15. EP260213a: Mephisto optical upper limits
  16. EP260223a: EP-FXT follow-up observation
  17. sb26021801: SVOM/VT optical upper limits
  18. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  19. sb26021801: SVOM/C-GFT upper limit
  20. EP260223a: COLIBRÍ optical upper limits
  21. EP260223a: Einstein Probe detection of an X-ray transient
  22. GRB 260223A: SVOM/VT optical observation
  23. GRB 260223A: SVOM/GRM observation
  24. GRB 260223A: COLIBRÍ further optical observations and a brightening
  25. EP260221a: Optical upper limit with Kinder observations
  26. GRB 260223A: COLIBRÍ optical observations
  27. GRB 260223A: DDOTI Optical Candidate
  28. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  29. Fermi GRB 260223A: Global MASTER-Net observations report
  30. GRB 260223A: Fermi GBM Final Real-time Localization
  31. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  32. EP260221a: COLIBRÍ optical counterpart candidate
  33. EP260221a: Gemini South z-band upper limit
  34. GRB 260222A: Fermi GBM Final Real-time Localization
  35. EP260221a: Global MASTER-Net observations report
  36. EP260221a: EP-FXT follow-up observation
  37. Fermi GRB 260221B: Global MASTER-Net observations report
  38. GRB 260221B: Fermi GBM Final Real-time Localization
  39. EP-WXT01709258519: Xinglong optical upper limit
  40. EP260221a: Xinglong optical upper limit
  41. Fermi GRB 260221A: Global MASTER-Net observations report
  42. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  43. GRB 260221A: Fermi GBM Final Real-time Localization
  44. EP260221a: GOTO optical upper limit
  45. EP260221a: COLIBRÍ optical upper limit
  46. SVOM alert sb26021801: LCO optical upper limit
  47. EP260221a: Einstein Probe detection of an X-ray transient
  48. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  49. GRB 260219A: AstroSat CZTI detection
  50. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  51. GRB 260219A: GECAM-B observation of a long burst
  52. Fermi GRB 260219A: Global MASTER-Net observations report
  53. GRB 260219A: Fermi GBM Final Real-time Localization
  54. SVOM alert sb26021801: LAST optical upper limit
  55. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  56. IceCube Alert 260217A: Global MASTER-Net observations report
  57. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  58. GRB 260217A: Fermi GBM Final Localization
  59. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  60. sb26021801: SVOM detection of a long faint X-ray transient
  61. The EP-WXT trigger 01709258455 is likely a flaring star
  62. EP-WXT 01709258455: NOT optical upper limits
  63. EP260214b: Mondy optical observations
  64. EP260214b: 1.3m DFOT optical upper limit
  65. EP260210a: Mondy optical upper limits
  66. Konus-Wind detection of GRB 260212A
  67. GRB 260208A: AbAO and Terskol optical upper limits
  68. GRB 260208A: continued Mondy optical observations
  69. IPN triangulation of GRB 260212A
  70. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 260213A: GECAM-B observation of a short burst
  72. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  73. GRB 260216A: Fermi GBM Final Real-time Localization
  74. EP260214b: Liverpool Telescope optical observations
  75. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  76. EP260214b: Optical upper limit with Kinder observations
  77. EP260214a: Optical upper limits with Kinder observations
  78. EP260214b: EP-FXT follow-up observation
  79. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  80. EP260214b: DDOTI Optical Detection
  81. EP260214b: GROWTH-India Telescope optical upper limit
  82. EP260214a: VLT near-infrared observation
  83. EP260214b: SVOM/VT optical observation
  84. EP260214a: NOT optical upper limits
  85. EP260214a: COLIBRÍ optical upper limits
  86. EP260214b: OHP/T120 optical observations
  87. EP260214a: refined analysis of the EP-FXT observation
  88. EP260214b: LCO optical counterpart detection
  89. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  90. GRB 260211A: SVOM/VT optical counterpart
  91. EP260214b: COLIBRÍ optical observations
  92. EP260214a: SVOM/VT optical upper limits
  93. EP260214b: NOT optical counterpart detection
  94. EP260214b: Einstein Probe detection of a fast X-ray transient
  95. EP260214a: Global MASTER-Net observations report
  96. EP260214a: Einstein Probe detection of an X-ray transient
  97. GRB 260212A: AstroSat CZTI detection
  98. GRB 260212A: Fermi GBM Observation
  99. EP260213a: Liverpool Telescope optical upper limits
  100. EP260213a: Global MASTER-Net observations report

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