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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"

26507 results found.

  1. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  2. EP260221a: GOTO optical upper limit
  3. EP260221a: COLIBRÍ optical upper limit
  4. SVOM alert sb26021801: LCO optical upper limit
  5. EP260221a: Einstein Probe detection of an X-ray transient
  6. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  7. GRB 260219A: GECAM-B observation of a long burst
  8. SVOM alert sb26021801: LAST optical upper limit
  9. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  10. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  11. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  12. sb26021801: SVOM detection of a long faint X-ray transient
  13. The EP-WXT trigger 01709258455 is likely a flaring star
  14. EP-WXT 01709258455: NOT optical upper limits
  15. EP260214b: Mondy optical observations
  16. EP260214b: 1.3m DFOT optical upper limit
  17. EP260210a: Mondy optical upper limits
  18. Konus-Wind detection of GRB 260212A
  19. GRB 260208A: AbAO and Terskol optical upper limits
  20. GRB 260208A: continued Mondy optical observations
  21. IPN triangulation of GRB 260212A
  22. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  23. EP260214b: Liverpool Telescope optical observations
  24. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  25. EP260214b: Optical upper limit with Kinder observations
  26. EP260214a: Optical upper limits with Kinder observations
  27. EP260214b: EP-FXT follow-up observation
  28. EP260214b: DDOTI Optical Detection
  29. EP260214b: GROWTH-India Telescope optical upper limit
  30. EP260214a: VLT near-infrared observation
  31. EP260214a: NOT optical upper limits
  32. EP260214a: COLIBRÍ optical upper limits
  33. EP260214b: OHP/T120 optical observations
  34. EP260214a: refined analysis of the EP-FXT observation
  35. EP260214b: LCO optical counterpart detection
  36. EP260214b: COLIBRÍ optical observations
  37. EP260214b: NOT optical counterpart detection
  38. EP260214b: Einstein Probe detection of a fast X-ray transient
  39. EP260214a: Einstein Probe detection of an X-ray transient
  40. GRB 260212A: AstroSat CZTI detection
  41. GRB 260212A: Fermi GBM Observation
  42. EP260213a: Liverpool Telescope optical upper limits
  43. EP260213a: COLIBRÍ optical upper limits
  44. GRB 260212A: GECAM-B observation
  45. EP260213a: Optical upper limits with Kinder observations
  46. EP260213a: Mondy R-band optical upper limit
  47. EP260213a: SVOM/C-GFT upper limit
  48. EP260213a: refined analysis of the EP-FXT observation
  49. EP260213a: Einstein Probe detection of a fast X-ray transient
  50. EP/WXT 01709258378: NOT optical upper limits
  51. GRB 260212A: SVOM/GRM observation of a long burst
  52. GRB 260211A - SVOM/ECLAIRs refined analysis
  53. GRB 260212A: Glowbug gamma-ray detection
  54. GRB 260211A: LAST optical upper limit
  55. GRB 260210A: SVOM/GRM observation
  56. Konus-Wind detection of GRB 260207B
  57. GRB 260211A: LCO optical upper limits
  58. GRB260131A/B: 3.6m DOT Optical Observations
  59. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  60. GRB 260211A: SVOM detection of a burst
  61. Konus-Wind detection of GRB 260209B
  62. Konus-Wind detection of GRB 260127B
  63. EP260209a: COLIBRÍ optical upper limit
  64. EP260209a: LCO optical upper limits
  65. EP260210a: refined analysis of the EP-FXT observation
  66. GRB 260208A: LCO detection of the optical counterpart
  67. EP260209a: Einstein Probe detection of a fast X-ray transient
  68. EP260210a: Optical upper limits with Kinder observations
  69. IPN triangulation of GRB 260207B (short/hard with EE)
  70. GRB 260210A: Glowbug gamma-ray detection
  71. GRB 260210A: AstroSat CZTI detection
  72. EP260210a: COLIBRÍ optical upper limit
  73. EP260210a: SVOM/C-GFT upper limit
  74. GRB 260208B: refined analysis of the EP-FXT observation
  75. EP260210a: Einstein Probe detection of an X-ray transient
  76. GRB 260208C: SVOM/GRM observation
  77. GRB 260204A: Swift-XRT afterglow detection
  78. GRB 260208B: AstroSat CZTI detection of a bright long burst
  79. GRB260208A: Liverpool Telescope optical follow-up observations
  80. GRB 260208A: Glowbug gamma-ray detection
  81. GRB 260208A: Fermi GBM Observation
  82. GRB 260208B: Swift-XRT observations
  83. GRB 260131A/B: continued Mondy optical observations
  84. GRB 260204A: Swift/UVOT Upper Limits
  85. GRB 260208B: COLIBRÍ optical observations
  86. GRB 260208A: Mondy optical observations
  87. GRB 260208A: 1.3m DFOT optical detection
  88. GRB 260208A: COLIBRÍ optical observations
  89. GRB 260208B: EP-FXT observation
  90. GRB 260208A: GECAM-B observation of a bright burst
  91. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  92. GRB 260208A: SVOM/VT optical observation
  93. GRB 260208A: Swift-XRT observations
  94. GRB 260208B: SVOM/GRM observation of a bright burst
  95. GRB 260208B: Fermi GBM Detection
  96. GRB 260208B: Fermi-LAT detection
  97. GRB 260207B: GECAM-B observation
  98. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  99. GRB 260131A/B: Mondy and Terskol optical observations
  100. GRB 260206A: Swift-XRT observations

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