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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"

28887 results found.

  1. EP-WXT01709258519: Xinglong optical upper limit
  2. EP260221a: Xinglong optical upper limit
  3. Fermi GRB 260221A: Global MASTER-Net observations report
  4. GRB 260221A: Fermi GBM Final Real-time Localization
  5. EP260221a: GOTO optical upper limit
  6. EP260221a: COLIBRÍ optical upper limit
  7. SVOM alert sb26021801: LCO optical upper limit
  8. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  9. GRB 260219A: AstroSat CZTI detection
  10. GRB 260219A: GECAM-B observation of a long burst
  11. Fermi GRB 260219A: Global MASTER-Net observations report
  12. GRB 260219A: Fermi GBM Final Real-time Localization
  13. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  14. IceCube Alert 260217A: Global MASTER-Net observations report
  15. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  16. GRB 260217A: Fermi GBM Final Localization
  17. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  18. sb26021801: SVOM detection of a long faint X-ray transient
  19. The EP-WXT trigger 01709258455 is likely a flaring star
  20. EP-WXT 01709258455: NOT optical upper limits
  21. EP260214b: 1.3m DFOT optical upper limit
  22. Konus-Wind detection of GRB 260212A
  23. GRB 260208A: AbAO and Terskol optical upper limits
  24. GRB 260208A: continued Mondy optical observations
  25. IPN triangulation of GRB 260212A
  26. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  27. GRB 260213A: GECAM-B observation of a short burst
  28. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  29. GRB 260216A: Fermi GBM Final Real-time Localization
  30. EP260214b: Liverpool Telescope optical observations
  31. EP260214b: Optical upper limit with Kinder observations
  32. EP260214a: Optical upper limits with Kinder observations
  33. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  34. EP260214b: DDOTI Optical Detection
  35. EP260214b: GROWTH-India Telescope optical upper limit
  36. EP260214a: VLT near-infrared observation
  37. EP260214b: SVOM/VT optical observation
  38. EP260214a: NOT optical upper limits
  39. EP260214a: COLIBRÍ optical upper limits
  40. EP260214b: OHP/T120 optical observations
  41. EP260214b: LCO optical counterpart detection
  42. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  43. GRB 260211A: SVOM/VT optical counterpart
  44. EP260214b: COLIBRÍ optical observations
  45. EP260214a: SVOM/VT optical upper limits
  46. EP260214b: NOT optical counterpart detection
  47. EP260214a: Global MASTER-Net observations report
  48. GRB 260212A: AstroSat CZTI detection
  49. GRB 260212A: Fermi GBM Observation
  50. EP260213a: Global MASTER-Net observations report
  51. EP260213a: COLIBRÍ optical upper limits
  52. GRB 260212A: GECAM-B observation
  53. EP260213a: Optical upper limits with Kinder observations
  54. EP260213a: SVOM/VT optical upper limit
  55. EP260213a: NUTTelA-TAO Early Optical Limits
  56. EP260213a: SVOM/C-GFT upper limit
  57. EP/WXT 01709258378: NOT optical upper limits
  58. GRB 260212A: SVOM/GRM observation of a long burst
  59. GRB 260213B: Fermi GBM Final Localization
  60. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  61. GRB 260211A - SVOM/ECLAIRs refined analysis
  62. GRB 260204A: SVOM/ECLAIRs refined analysis
  63. GRB 260213A: Fermi GBM Final Localization
  64. GRB 260211A: EP-FXT follow-up observation
  65. GRB 260211A: SVOM/VT optical observation
  66. GRB 260212A: Glowbug gamma-ray detection
  67. GRB 260211A: GOTO optical upper limit
  68. Fermi GRB 260212A: Global MASTER-Net observations report
  69. GRB 260212A: Fermi GBM Final Real-time Localization
  70. GRB 260210A: SVOM/GRM observation
  71. Fermi GBM Sub-Threshold Detection of GRB 260211A
  72. Konus-Wind detection of GRB 260207B
  73. GRID detection of GRB 260207B
  74. GRB 260211A: LCO optical upper limits
  75. GRB260131A/B: 3.6m DOT Optical Observations
  76. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  77. Fermi trigger No 792537871: Global MASTER-Net observations report
  78. GRB 260211A: SVOM detection of a burst
  79. GRB 260208A: Swift UVOT detection
  80. Konus-Wind detection of GRB 260127B
  81. EP260209a: COLIBRÍ optical upper limit
  82. Fermi GRB 260210C: Global MASTER-Net observations report
  83. EP260209a: LCO optical upper limits
  84. EP260210a: Global MASTER-Net observations report
  85. EP260210a: refined analysis of the EP-FXT observation
  86. EP260209a: Global MASTER-Net observations report
  87. GRB 260208A: LCO detection of the optical counterpart
  88. EP260210a: Optical upper limits with Kinder observations
  89. IPN triangulation of GRB 260207B (short/hard with EE)
  90. GRB 260210C: Fermi GBM Final Real-time Localization
  91. GRB 260210B: Fermi GBM Final Real-time Localization
  92. EP260210a: SVOM/VT optical upper limit
  93. GRB 260208C: AstroSat CZTI detection
  94. EP260210a: COLIBRÍ optical upper limit
  95. EP260210a: SVOM/C-GFT upper limit
  96. GRB 260208B: refined analysis of the EP-FXT observation
  97. GRB 260207B: AstroSat CZTI detection
  98. GRB 260208C: SVOM/GRM observation
  99. GRB 260208B: AstroSat CZTI detection of a bright long burst
  100. GRB260208A: Liverpool Telescope optical follow-up observations

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