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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"

32546 results found.

  1. EP260227a: Global MASTER-Net observations report
  2. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  3. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  4. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  5. Konus-Wind detection of GRB 260226A
  6. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  7. EP260214a: VLT/FORS2 optical observations
  8. GRB 260225A: WINTER J-band upper limit
  9. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  10. GRB 260226A: COLIBRÍ optical upper limits
  11. GRB 260226A: LCOGT Optical Upper Limit
  12. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  13. GRB 260226A: Glowbug gamma-ray detection
  14. GRB 260226A: NuSTAR detection of bright prompt emission
  15. GRB 260226A : GROWTH-India Telescope optical observations
  16. GRB 260226A: LAST optical upper limit
  17. GRB 260226A: Fermi GBM observation
  18. GRB 260226A: Fermi-LAT refined analysis
  19. Fermi GRB 260226A: Global MASTER-Net observations report
  20. GRB 260226A: AstroSat CZTI detection of bright long burst
  21. EP260214a: VLA 6 GHz detection
  22. GRB 260226A: Fermi-LAT detection of a bright burst
  23. EP260224a: LCO optical upper limits
  24. GRB260225A: SVOM/ECLAIRs refined position
  25. GRB 260225A: EP-FXT follow-up observation
  26. GRB 260225A: SVOM/VT optical observation
  27. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  28. GRB 260223A: Fermi GBM Observation
  29. GRB 260225A: SVOM/VT optical upper limits
  30. EP260126a: VLA 6 GHz detection
  31. EP260223a: Liverpool Telescope upper limits
  32. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  33. EP 260225.148: COLIBRÍ Confirmation of flaring star
  34. EP260223a: Xinglong optical upper limit
  35. GRB 260223A: Glowbug gamma-ray detection
  36. EP260213a: Mephisto optical upper limits
  37. EP260223a: EP-FXT follow-up observation
  38. sb26021801: SVOM/VT optical upper limits
  39. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  40. sb26021801: SVOM/C-GFT upper limit
  41. EP260223a: COLIBRÍ optical upper limits
  42. GRB 260223A: SVOM/VT optical observation
  43. GRB 260223A: SVOM/GRM observation
  44. GRB 260223A: COLIBRÍ further optical observations and a brightening
  45. EP260221a: Optical upper limit with Kinder observations
  46. GRB 260223A: COLIBRÍ optical observations
  47. GRB 260223A: DDOTI Optical Candidate
  48. Fermi GRB 260223A: Global MASTER-Net observations report
  49. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  50. EP260221a: COLIBRÍ optical counterpart candidate
  51. EP260221a: Gemini South z-band upper limit
  52. EP260221a: Global MASTER-Net observations report
  53. EP260221a: EP-FXT follow-up observation
  54. Fermi GRB 260221B: Global MASTER-Net observations report
  55. EP260221a: Xinglong optical upper limit
  56. Fermi GRB 260221A: Global MASTER-Net observations report
  57. EP260221a: GOTO optical upper limit
  58. EP260221a: COLIBRÍ optical upper limit
  59. SVOM alert sb26021801: LCO optical upper limit
  60. GRB 260219A: AstroSat CZTI detection
  61. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  62. GRB 260219A: GECAM-B observation of a long burst
  63. Fermi GRB 260219A: Global MASTER-Net observations report
  64. SVOM alert sb26021801: LAST optical upper limit
  65. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  66. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  67. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  68. EP260214b: Mondy optical observations
  69. EP260214b: 1.3m DFOT optical upper limit
  70. EP260210a: Mondy optical upper limits
  71. Konus-Wind detection of GRB 260212A
  72. GRB 260208A: AbAO and Terskol optical upper limits
  73. GRB 260208A: continued Mondy optical observations
  74. IPN triangulation of GRB 260212A
  75. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  76. GRB 260213A: GECAM-B observation of a short burst
  77. EP260214b: Liverpool Telescope optical observations
  78. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  79. EP260214b: Optical upper limit with Kinder observations
  80. EP260214a: Optical upper limits with Kinder observations
  81. EP260214b: EP-FXT follow-up observation
  82. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  83. EP260214b: DDOTI Optical Detection
  84. EP260214b: GROWTH-India Telescope optical upper limit
  85. EP260214a: VLT near-infrared observation
  86. EP260214b: SVOM/VT optical observation
  87. EP260214a: NOT optical upper limits
  88. EP260214a: COLIBRÍ optical upper limits
  89. EP260214b: OHP/T120 optical observations
  90. EP260214a: refined analysis of the EP-FXT observation
  91. EP260214b: LCO optical counterpart detection
  92. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  93. GRB 260211A: SVOM/VT optical counterpart
  94. EP260214b: COLIBRÍ optical observations
  95. EP260214a: SVOM/VT optical upper limits
  96. EP260214b: NOT optical counterpart detection
  97. EP260214a: Global MASTER-Net observations report
  98. GRB 260212A: AstroSat CZTI detection
  99. GRB 260212A: Fermi GBM Observation
  100. EP260213a: Liverpool Telescope optical upper limits

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