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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"

14824 results found.

  1. EP260221a: Einstein Probe detection of an X-ray transient
  2. GRB 260219A: AstroSat CZTI detection
  3. GRB 260219A: Fermi GBM Final Real-time Localization
  4. GRB 260217A: Fermi GBM Final Localization
  5. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  6. sb26021801: SVOM detection of a long faint X-ray transient
  7. EP260214b: Mondy optical observations
  8. EP260214b: 1.3m DFOT optical upper limit
  9. Konus-Wind detection of GRB 260212A
  10. IPN triangulation of GRB 260212A
  11. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  12. GRB 260216A: Fermi GBM Final Real-time Localization
  13. EP260214b: Liverpool Telescope optical observations
  14. EP260214b: Optical upper limit with Kinder observations
  15. EP260214a: Optical upper limits with Kinder observations
  16. EP260214b: EP-FXT follow-up observation
  17. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  18. EP260214b: DDOTI Optical Detection
  19. EP260214b: GROWTH-India Telescope optical upper limit
  20. EP260214b: SVOM/VT optical observation
  21. EP260214a: NOT optical upper limits
  22. EP260214b: OHP/T120 optical observations
  23. EP260214b: LCO optical counterpart detection
  24. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  25. EP260214b: COLIBRÍ optical observations
  26. EP260214b: NOT optical counterpart detection
  27. EP260214b: Einstein Probe detection of a fast X-ray transient
  28. EP260214a: Einstein Probe detection of an X-ray transient
  29. GRB 260212A: AstroSat CZTI detection
  30. EP260213a: Liverpool Telescope optical upper limits
  31. EP260213a: Optical upper limits with Kinder observations
  32. EP260213a: Einstein Probe detection of a fast X-ray transient
  33. GRB 260213B: Fermi GBM Final Localization
  34. GRB 260204A: SVOM/ECLAIRs refined analysis
  35. GRB 260213A: Fermi GBM Final Localization
  36. GRB 260212A: Glowbug gamma-ray detection
  37. GRB 260212A: Fermi GBM Final Real-time Localization
  38. Fermi GBM Sub-Threshold Detection of GRB 260211A
  39. Konus-Wind detection of GRB 260207B
  40. GRID detection of GRB 260207B
  41. GRB260131A/B: 3.6m DOT Optical Observations
  42. GRB 260211A: SVOM detection of a burst
  43. Konus-Wind detection of GRB 260209B
  44. GRB 260208A: Swift UVOT detection
  45. Konus-Wind detection of GRB 260127B
  46. GRB 260208A: LCO detection of the optical counterpart
  47. EP260209a: Einstein Probe detection of a fast X-ray transient
  48. IPN triangulation of GRB 260207B (short/hard with EE)
  49. GRB 260210C: Fermi GBM Final Real-time Localization
  50. GRB 260210A: Glowbug gamma-ray detection
  51. GRB 260210B: Fermi GBM Final Real-time Localization
  52. GRB 260210A: AstroSat CZTI detection
  53. GRB 260208C: AstroSat CZTI detection
  54. EP260210a: Einstein Probe detection of an X-ray transient
  55. GRB 260207B: AstroSat CZTI detection
  56. GRB 260204A: Swift-XRT afterglow detection
  57. GRB 260208B: AstroSat CZTI detection of a bright long burst
  58. GRB 260208A: Glowbug gamma-ray detection
  59. GRB 260208A: NuSTAR detection of prompt emission
  60. GRB 260208A: 1.3m DFOT optical detection
  61. GRB 260208A: NOT spectroscopic redshift z = 2.36
  62. GRB 260208A: Liverpool Telescope optical detection
  63. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  64. GRB 260209A: Fermi GBM Final Real-time Localization
  65. GRB 260208D: Fermi GBM Final Real-time Localization
  66. GRB 260208B: Fermi GBM Detection
  67. GRB 260208B: Fermi-LAT detection
  68. GRB 260208C: Fermi GBM Final Real-time Localization
  69. GRB 260208A: Fermi-LAT detection
  70. GRB 260208A: Fermi GBM Classification Correction
  71. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  72. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  73. GRB 260208B: Fermi GBM Final Real-time Localization
  74. GRB 260208A: Fermi GBM Final Real-time Localization
  75. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  76. GRB 260207A : MASTER optical counterpart discovery
  77. GRB 260206A: Swift-XRT observations
  78. GRB 260207B: Fermi GBM Final Real-time Localization
  79. GRB 260207A: Fermi GBM Final Localization
  80. EP260131a: VLA detection
  81. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  82. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  83. GRB 260204A: LCO optical afterglow detection
  84. Fermi GBM Sub-Threshold Detection of GRB 260204A
  85. GRB 260204B: Fermi GBM Final Real-time Localization
  86. GRB 260204A: SVOM detection of a burst
  87. GRB 260121A: 239Alferov CubeSat detection
  88. Konus-Wind detection of GRB 260121A
  89. GRB 251230A: MeerLICHT afterglow detection
  90. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  91. GRID detection of GRB 260131A/B
  92. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  93. GRB 260130A: Insight-HXMT/HE detection
  94. GRB 260131A/B: EP/FXT X-ray afterglow detection
  95. GRB 260127B: Insight-HXMT/HE detection
  96. GRB 260131A: NOT spectroscopic redshift z = 1.434
  97. Konus-Wind detection of GRB 260128A / EP260128a
  98. GRB 260131A: Insight-HXMT/HE detection
  99. Konus-Wind detection of GRB 260131A/B
  100. EP260131a: Xinglong optical upper limit

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