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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

20501 results found.

  1. EP260221a: GOTO optical upper limit
  2. EP260221a: COLIBRÍ optical upper limit
  3. SVOM alert sb26021801: LCO optical upper limit
  4. EP260221a: Einstein Probe detection of an X-ray transient
  5. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  6. GRB 260219A: GECAM-B observation of a long burst
  7. SVOM alert sb26021801: LAST optical upper limit
  8. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  9. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  10. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  11. EP-WXT 01709258455: NOT optical upper limits
  12. EP260214b: Mondy optical observations
  13. EP260214b: 1.3m DFOT optical upper limit
  14. EP260210a: Mondy optical upper limits
  15. GRB 260208A: AbAO and Terskol optical upper limits
  16. GRB 260208A: continued Mondy optical observations
  17. IPN triangulation of GRB 260212A
  18. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  19. EP260214b: Liverpool Telescope optical observations
  20. EP260214b: Optical upper limit with Kinder observations
  21. EP260214a: Optical upper limits with Kinder observations
  22. EP260214b: EP-FXT follow-up observation
  23. EP260214b: DDOTI Optical Detection
  24. EP260214b: GROWTH-India Telescope optical upper limit
  25. EP260214a: VLT near-infrared observation
  26. EP260214a: NOT optical upper limits
  27. EP260214a: COLIBRÍ optical upper limits
  28. EP260214b: OHP/T120 optical observations
  29. EP260214a: refined analysis of the EP-FXT observation
  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. EP260213a: Liverpool Telescope optical upper limits
  37. EP260213a: COLIBRÍ optical upper limits
  38. EP260213a: Optical upper limits with Kinder observations
  39. EP260213a: Mondy R-band optical upper limit
  40. EP260213a: NUTTelA-TAO Early Optical Limits
  41. EP260213a: SVOM/C-GFT upper limit
  42. EP260213a: refined analysis of the EP-FXT observation
  43. EP260213a: Einstein Probe detection of a fast X-ray transient
  44. EP/WXT 01709258378: NOT optical upper limits
  45. GRB 260212A: SVOM/GRM observation of a long burst
  46. GRB 260211A - SVOM/ECLAIRs refined analysis
  47. GRB 260204A: SVOM/ECLAIRs refined analysis
  48. GRB 260211A: LAST optical upper limit
  49. GRB 260210A: SVOM/GRM observation
  50. GRB 260128B: SVOM/ECLAIRs refined analysis
  51. GRID detection of GRB 260207B
  52. GRB 260211A: LCO optical upper limits
  53. GRB260131A/B: 3.6m DOT Optical Observations
  54. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  55. GRB 260211A: SVOM detection of a burst
  56. EP260209a: COLIBRÍ optical upper limit
  57. EP260209a: LCO optical upper limits
  58. EP260210a: refined analysis of the EP-FXT observation
  59. GRB 260208A: LCO detection of the optical counterpart
  60. EP260209a: Einstein Probe detection of a fast X-ray transient
  61. EP260210a: Optical upper limits with Kinder observations
  62. GRB 260208C: AstroSat CZTI detection
  63. EP260210a: COLIBRÍ optical upper limit
  64. EP260210a: SVOM/C-GFT upper limit
  65. EP260210a: Einstein Probe detection of an X-ray transient
  66. GRB 260208C: SVOM/GRM observation
  67. GRB 260204A: Swift-XRT afterglow detection
  68. GRB 260208B: AstroSat CZTI detection of a bright long burst
  69. GRB260208A: Liverpool Telescope optical follow-up observations
  70. GRB 260131A/B: continued Mondy optical observations
  71. GRB 260204A: Swift/UVOT Upper Limits
  72. GRB 260208B: COLIBRÍ optical observations
  73. GRB 260208A: Mondy optical observations
  74. GRB 260208A: 1.3m DFOT optical detection
  75. GRB 260208A: COLIBRÍ optical observations
  76. GRB 260208A: NOT spectroscopic redshift z = 2.36
  77. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  78. GRB 260208A: SVOM/VT optical observation
  79. Fermi GRB 260208D: Global MASTER-Net observations report
  80. GRB 260208B: SVOM/GRM observation of a bright burst
  81. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  82. GRB 260131A/B: Mondy and Terskol optical observations
  83. GRB 260204A: Swift-XRT observations
  84. GRB 260204A: SVOM/VT optical candidate
  85. GRB 260204A: LCO optical upper limits
  86. EP260110a: Late GTC/EMIR near-infrared observations
  87. GRB 260204B: Fermi GBM Final Real-time Localization
  88. Konus-Wind detection of GRB 260121A
  89. GRB 260131A: KAIT optical observations
  90. GRB 251230A: MeerLICHT afterglow detection
  91. GRID detection of GRB 260131A/B
  92. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  93. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  94. GRB 260131A: NOT spectroscopic redshift z = 1.434
  95. EP260131a: Liverpool Telescope optical upper limits
  96. EP260131a: COLIBRÍ further observations
  97. Konus-Wind detection of GRB 260128A / EP260128a
  98. EP260131a: SVOM/VT optical observation
  99. EP260131a: Xinglong optical upper limit
  100. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading

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