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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"

32532 results found.

  1. GRB 260226A: LAST optical upper limit
  2. GRB 260226A: Fermi GBM observation
  3. GRB 260226A: Fermi-LAT refined analysis
  4. Fermi GRB 260226A: Global MASTER-Net observations report
  5. GRB 260226A: AstroSat CZTI detection of bright long burst
  6. EP260214a: VLA 6 GHz detection
  7. GRB 260226A: Fermi-LAT detection of a bright burst
  8. EP260224a: LCO optical upper limits
  9. GRB260225A: SVOM/ECLAIRs refined position
  10. GRB 260225A: EP-FXT follow-up observation
  11. GRB 260225A: SVOM/VT optical observation
  12. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  13. GRB 260223A: Fermi GBM Observation
  14. GRB 260225A: SVOM/VT optical upper limits
  15. EP260126a: VLA 6 GHz detection
  16. EP260223a: Liverpool Telescope upper limits
  17. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  18. EP 260225.148: COLIBRÍ Confirmation of flaring star
  19. EP260223a: Xinglong optical upper limit
  20. GRB 260223A: Glowbug gamma-ray detection
  21. EP260213a: Mephisto optical upper limits
  22. EP260223a: EP-FXT follow-up observation
  23. sb26021801: SVOM/VT optical upper limits
  24. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  25. sb26021801: SVOM/C-GFT upper limit
  26. EP260223a: COLIBRÍ optical upper limits
  27. GRB 260223A: SVOM/VT optical observation
  28. GRB 260223A: SVOM/GRM observation
  29. GRB 260223A: COLIBRÍ further optical observations and a brightening
  30. EP260221a: Optical upper limit with Kinder observations
  31. GRB 260223A: COLIBRÍ optical observations
  32. GRB 260223A: DDOTI Optical Candidate
  33. Fermi GRB 260223A: Global MASTER-Net observations report
  34. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  35. EP260221a: COLIBRÍ optical counterpart candidate
  36. EP260221a: Gemini South z-band upper limit
  37. EP260221a: Global MASTER-Net observations report
  38. EP260221a: EP-FXT follow-up observation
  39. Fermi GRB 260221B: Global MASTER-Net observations report
  40. EP260221a: Xinglong optical upper limit
  41. Fermi GRB 260221A: Global MASTER-Net observations report
  42. EP260221a: GOTO optical upper limit
  43. EP260221a: COLIBRÍ optical upper limit
  44. SVOM alert sb26021801: LCO optical upper limit
  45. GRB 260219A: AstroSat CZTI detection
  46. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  47. GRB 260219A: GECAM-B observation of a long burst
  48. Fermi GRB 260219A: Global MASTER-Net observations report
  49. SVOM alert sb26021801: LAST optical upper limit
  50. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  51. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  52. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  53. EP260214b: Mondy optical observations
  54. EP260214b: 1.3m DFOT optical upper limit
  55. EP260210a: Mondy optical upper limits
  56. Konus-Wind detection of GRB 260212A
  57. GRB 260208A: AbAO and Terskol optical upper limits
  58. GRB 260208A: continued Mondy optical observations
  59. IPN triangulation of GRB 260212A
  60. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  61. GRB 260213A: GECAM-B observation of a short burst
  62. EP260214b: Liverpool Telescope optical observations
  63. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  64. EP260214b: Optical upper limit with Kinder observations
  65. EP260214a: Optical upper limits with Kinder observations
  66. EP260214b: EP-FXT follow-up observation
  67. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  68. EP260214b: DDOTI Optical Detection
  69. EP260214b: GROWTH-India Telescope optical upper limit
  70. EP260214a: VLT near-infrared observation
  71. EP260214b: SVOM/VT optical observation
  72. EP260214a: NOT optical upper limits
  73. EP260214a: COLIBRÍ optical upper limits
  74. EP260214b: OHP/T120 optical observations
  75. EP260214a: refined analysis of the EP-FXT observation
  76. EP260214b: LCO optical counterpart detection
  77. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  78. GRB 260211A: SVOM/VT optical counterpart
  79. EP260214b: COLIBRÍ optical observations
  80. EP260214a: SVOM/VT optical upper limits
  81. EP260214b: NOT optical counterpart detection
  82. EP260214a: Global MASTER-Net observations report
  83. GRB 260212A: AstroSat CZTI detection
  84. GRB 260212A: Fermi GBM Observation
  85. EP260213a: Liverpool Telescope optical upper limits
  86. EP260213a: Global MASTER-Net observations report
  87. EP260213a: COLIBRÍ optical upper limits
  88. GRB 260212A: GECAM-B observation
  89. EP260213a: Optical upper limits with Kinder observations
  90. EP260213a: SVOM/VT optical upper limit
  91. EP260213a: Mondy R-band optical upper limit
  92. EP260213a: NUTTelA-TAO Early Optical Limits
  93. EP260213a: SVOM/C-GFT upper limit
  94. EP260213a: refined analysis of the EP-FXT observation
  95. GRB 260212A: SVOM/GRM observation of a long burst
  96. GRB 260211A - SVOM/ECLAIRs refined analysis
  97. GRB 260204A: SVOM/ECLAIRs refined analysis
  98. GRB 260211A: EP-FXT follow-up observation
  99. GRB 260211A: SVOM/VT optical observation
  100. GRB 260212A: Glowbug gamma-ray detection

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