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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"

14831 results found.

  1. EP260221a: COLIBRÍ optical counterpart candidate
  2. EP260221a: Gemini South z-band upper limit
  3. GRB 260222A: Fermi GBM Final Real-time Localization
  4. GRB 260221B: Fermi GBM Final Real-time Localization
  5. EP-WXT01709258519: Xinglong optical upper limit
  6. EP260221a: Xinglong optical upper limit
  7. GRB 260221A: Fermi GBM Final Real-time Localization
  8. EP260221a: Einstein Probe detection of an X-ray transient
  9. GRB 260219A: AstroSat CZTI detection
  10. GRB 260219A: Fermi GBM Final Real-time Localization
  11. GRB 260217A: Fermi GBM Final Localization
  12. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  13. sb26021801: SVOM detection of a long faint X-ray transient
  14. EP260214b: Mondy optical observations
  15. EP260214b: 1.3m DFOT optical upper limit
  16. Konus-Wind detection of GRB 260212A
  17. IPN triangulation of GRB 260212A
  18. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  19. GRB 260216A: Fermi GBM Final Real-time Localization
  20. EP260214b: Liverpool Telescope optical observations
  21. EP260214b: Optical upper limit with Kinder observations
  22. EP260214a: Optical upper limits with Kinder observations
  23. EP260214b: EP-FXT follow-up observation
  24. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  25. EP260214b: DDOTI Optical Detection
  26. EP260214b: GROWTH-India Telescope optical upper limit
  27. EP260214b: SVOM/VT optical observation
  28. EP260214a: NOT optical upper limits
  29. EP260214b: OHP/T120 optical observations
  30. EP260214b: LCO optical counterpart detection
  31. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  32. EP260214b: COLIBRÍ optical observations
  33. EP260214b: NOT optical counterpart detection
  34. EP260214b: Einstein Probe detection of a fast X-ray transient
  35. EP260214a: Einstein Probe detection of an X-ray transient
  36. GRB 260212A: AstroSat CZTI detection
  37. EP260213a: Liverpool Telescope optical upper limits
  38. EP260213a: Optical upper limits with Kinder observations
  39. EP260213a: Einstein Probe detection of a fast X-ray transient
  40. GRB 260213B: Fermi GBM Final Localization
  41. GRB 260204A: SVOM/ECLAIRs refined analysis
  42. GRB 260213A: Fermi GBM Final Localization
  43. GRB 260212A: Glowbug gamma-ray detection
  44. GRB 260212A: Fermi GBM Final Real-time Localization
  45. Fermi GBM Sub-Threshold Detection of GRB 260211A
  46. Konus-Wind detection of GRB 260207B
  47. GRID detection of GRB 260207B
  48. GRB260131A/B: 3.6m DOT Optical Observations
  49. GRB 260211A: SVOM detection of a burst
  50. Konus-Wind detection of GRB 260209B
  51. GRB 260208A: Swift UVOT detection
  52. Konus-Wind detection of GRB 260127B
  53. GRB 260208A: LCO detection of the optical counterpart
  54. EP260209a: Einstein Probe detection of a fast X-ray transient
  55. IPN triangulation of GRB 260207B (short/hard with EE)
  56. GRB 260210C: Fermi GBM Final Real-time Localization
  57. GRB 260210A: Glowbug gamma-ray detection
  58. GRB 260210B: Fermi GBM Final Real-time Localization
  59. GRB 260210A: AstroSat CZTI detection
  60. GRB 260208C: AstroSat CZTI detection
  61. EP260210a: Einstein Probe detection of an X-ray transient
  62. GRB 260207B: AstroSat CZTI detection
  63. GRB 260204A: Swift-XRT afterglow detection
  64. GRB 260208B: AstroSat CZTI detection of a bright long burst
  65. GRB 260208A: Glowbug gamma-ray detection
  66. GRB 260208A: NuSTAR detection of prompt emission
  67. GRB 260208A: 1.3m DFOT optical detection
  68. GRB 260208A: NOT spectroscopic redshift z = 2.36
  69. GRB 260208A: Liverpool Telescope optical detection
  70. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  71. GRB 260209A: Fermi GBM Final Real-time Localization
  72. GRB 260208D: Fermi GBM Final Real-time Localization
  73. GRB 260208B: Fermi GBM Detection
  74. GRB 260208B: Fermi-LAT detection
  75. GRB 260208C: Fermi GBM Final Real-time Localization
  76. GRB 260208A: Fermi-LAT detection
  77. GRB 260208A: Fermi GBM Classification Correction
  78. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  79. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  80. GRB 260208B: Fermi GBM Final Real-time Localization
  81. GRB 260208A: Fermi GBM Final Real-time Localization
  82. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  83. GRB 260207A : MASTER optical counterpart discovery
  84. GRB 260206A: Swift-XRT observations
  85. GRB 260207B: Fermi GBM Final Real-time Localization
  86. GRB 260207A: Fermi GBM Final Localization
  87. EP260131a: VLA detection
  88. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  89. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  90. GRB 260204A: LCO optical afterglow detection
  91. Fermi GBM Sub-Threshold Detection of GRB 260204A
  92. GRB 260204B: Fermi GBM Final Real-time Localization
  93. GRB 260204A: SVOM detection of a burst
  94. GRB 260121A: 239Alferov CubeSat detection
  95. Konus-Wind detection of GRB 260121A
  96. GRB 251230A: MeerLICHT afterglow detection
  97. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  98. GRID detection of GRB 260131A/B
  99. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  100. GRB 260130A: Insight-HXMT/HE detection

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