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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"

24261 results found.

  1. GRB 260225B: Fermi GBM Final Real-time Localization
  2. EP260126a: VLA 6 GHz detection
  3. GRB 260225A: SVOM detection of a burst
  4. EP260223a: Xinglong optical upper limit
  5. EP260213a: Mephisto optical upper limits
  6. sb26021801: SVOM/C-GFT upper limit
  7. GRB 260223A: SVOM/VT optical observation
  8. GRB 260223A: SVOM/GRM observation
  9. GRB 260223A: DDOTI Optical Candidate
  10. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  11. Fermi GRB 260223A: Global MASTER-Net observations report
  12. GRB 260223A: Fermi GBM Final Real-time Localization
  13. GRB 260222A: Fermi GBM Final Real-time Localization
  14. EP260221a: Global MASTER-Net observations report
  15. EP260221a: EP-FXT follow-up observation
  16. Fermi GRB 260221B: Global MASTER-Net observations report
  17. GRB 260221B: Fermi GBM Final Real-time Localization
  18. EP-WXT01709258519: Xinglong optical upper limit
  19. EP260221a: Xinglong optical upper limit
  20. Fermi GRB 260221A: Global MASTER-Net observations report
  21. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  22. GRB 260221A: Fermi GBM Final Real-time Localization
  23. EP260221a: GOTO optical upper limit
  24. SVOM alert sb26021801: LCO optical upper limit
  25. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  26. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  27. GRB 260219A: GECAM-B observation of a long burst
  28. Fermi GRB 260219A: Global MASTER-Net observations report
  29. GRB 260219A: Fermi GBM Final Real-time Localization
  30. IceCube Alert 260217A: Global MASTER-Net observations report
  31. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  32. GRB 260217A: Fermi GBM Final Localization
  33. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  34. sb26021801: SVOM detection of a long faint X-ray transient
  35. The EP-WXT trigger 01709258455 is likely a flaring star
  36. EP260214b: 1.3m DFOT optical upper limit
  37. Konus-Wind detection of GRB 260212A
  38. IPN triangulation of GRB 260212A
  39. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  40. GRB 260216A: Fermi GBM Final Real-time Localization
  41. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  42. EP260214a: Optical upper limits with Kinder observations
  43. EP260214b: EP-FXT follow-up observation
  44. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  45. EP260214b: DDOTI Optical Detection
  46. EP260214b: GROWTH-India Telescope optical upper limit
  47. EP260214b: SVOM/VT optical observation
  48. EP260214a: refined analysis of the EP-FXT observation
  49. EP260214a: SVOM/VT optical upper limits
  50. EP260214a: Global MASTER-Net observations report
  51. GRB 260212A: Fermi GBM Observation
  52. EP260213a: Global MASTER-Net observations report
  53. GRB 260212A: GECAM-B observation
  54. EP260213a: Optical upper limits with Kinder observations
  55. EP260213a: SVOM/VT optical upper limit
  56. EP260213a: NUTTelA-TAO Early Optical Limits
  57. EP260213a: SVOM/C-GFT upper limit
  58. EP260213a: refined analysis of the EP-FXT observation
  59. GRB 260212A: SVOM/GRM observation of a long burst
  60. GRB 260213B: Fermi GBM Final Localization
  61. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  62. GRB 260211A - SVOM/ECLAIRs refined analysis
  63. GRB 260204A: SVOM/ECLAIRs refined analysis
  64. GRB 260213A: Fermi GBM Final Localization
  65. GRB 260211A: EP-FXT follow-up observation
  66. GRB 260211A: SVOM/VT optical observation
  67. Fermi GRB 260212A: Global MASTER-Net observations report
  68. GRB 260212A: Fermi GBM Final Real-time Localization
  69. GRB 260210A: SVOM/GRM observation
  70. Fermi GBM Sub-Threshold Detection of GRB 260211A
  71. Konus-Wind detection of GRB 260207B
  72. GRB 260128B: SVOM/ECLAIRs refined analysis
  73. GRID detection of GRB 260207B
  74. GRB 260211A: LCO optical upper limits
  75. GRB260131A/B: 3.6m DOT Optical Observations
  76. Fermi trigger No 792537871: Global MASTER-Net observations report
  77. GRB 260211A: SVOM detection of a burst
  78. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  79. Konus-Wind detection of GRB 260209B
  80. Konus-Wind detection of GRB 260127B
  81. Fermi GRB 260210C: Global MASTER-Net observations report
  82. EP260210a: Global MASTER-Net observations report
  83. EP260210a: refined analysis of the EP-FXT observation
  84. EP260209a: Global MASTER-Net observations report
  85. EP260210a: Optical upper limits with Kinder observations
  86. IPN triangulation of GRB 260207B (short/hard with EE)
  87. GRB 260210C: Fermi GBM Final Real-time Localization
  88. GRB 260210B: Fermi GBM Final Real-time Localization
  89. EP260210a: SVOM/VT optical upper limit
  90. EP260210a: SVOM/C-GFT upper limit
  91. GRB 260208C: SVOM/GRM observation
  92. GRB260208A: Liverpool Telescope optical follow-up observations
  93. GRB 260208A: NuSTAR detection of prompt emission
  94. GRB 260208A: Fermi GBM Observation
  95. Fermi GRB 260209A: Global MASTER-Net observations report
  96. GRB 260208A: 1.3m DFOT optical detection
  97. Fermi GRB 260208C: Global MASTER-Net observations report
  98. GRB 260208B: SVOM/VT optical candidate
  99. GRB 260208A: GECAM-B observation of a bright burst
  100. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)

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