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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"

32541 results found.

  1. EP260213a: Mondy R-band optical upper limit
  2. EP260213a: NUTTelA-TAO Early Optical Limits
  3. EP260213a: SVOM/C-GFT upper limit
  4. EP260213a: refined analysis of the EP-FXT observation
  5. GRB 260212A: SVOM/GRM observation of a long burst
  6. GRB 260211A - SVOM/ECLAIRs refined analysis
  7. GRB 260204A: SVOM/ECLAIRs refined analysis
  8. GRB 260211A: EP-FXT follow-up observation
  9. GRB 260211A: SVOM/VT optical observation
  10. GRB 260212A: Glowbug gamma-ray detection
  11. GRB 260211A: GOTO optical upper limit
  12. Fermi GRB 260212A: Global MASTER-Net observations report
  13. GRB 260211A: LAST optical upper limit
  14. GRB 260210A: SVOM/GRM observation
  15. Fermi GBM Sub-Threshold Detection of GRB 260211A
  16. Konus-Wind detection of GRB 260207B
  17. GRB 260128B: SVOM/ECLAIRs refined analysis
  18. GRID detection of GRB 260207B
  19. GRB 260211A: LCO optical upper limits
  20. GRB260131A/B: 3.6m DOT Optical Observations
  21. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  22. GRB 260208A: Swift UVOT detection
  23. Konus-Wind detection of GRB 260127B
  24. EP260209a: COLIBRÍ optical upper limit
  25. Fermi GRB 260210C: Global MASTER-Net observations report
  26. EP260209a: LCO optical upper limits
  27. EP260210a: Global MASTER-Net observations report
  28. EP260210a: refined analysis of the EP-FXT observation
  29. EP260209a: Global MASTER-Net observations report
  30. GRB 260208A: LCO detection of the optical counterpart
  31. EP260210a: Optical upper limits with Kinder observations
  32. IPN triangulation of GRB 260207B (short/hard with EE)
  33. GRB 260210A: Glowbug gamma-ray detection
  34. EP260210a: SVOM/VT optical upper limit
  35. GRB 260210A: AstroSat CZTI detection
  36. GRB 260208C: AstroSat CZTI detection
  37. EP260210a: COLIBRÍ optical upper limit
  38. EP260210a: SVOM/C-GFT upper limit
  39. GRB 260208B: refined analysis of the EP-FXT observation
  40. GRB 260207B: AstroSat CZTI detection
  41. GRB 260208C: SVOM/GRM observation
  42. GRB 260204A: Swift-XRT afterglow detection
  43. GRB 260208B: AstroSat CZTI detection of a bright long burst
  44. GRB260208A: Liverpool Telescope optical follow-up observations
  45. GRB 260208A: Glowbug gamma-ray detection
  46. GRB 260208A: NuSTAR detection of prompt emission
  47. GRB 260208A: Fermi GBM Observation
  48. Fermi GRB 260209A: Global MASTER-Net observations report
  49. GRB 260208B: Swift-XRT observations
  50. GRB 260131A/B: continued Mondy optical observations
  51. GRB 260204A: Swift/UVOT Upper Limits
  52. GRB 260208B: COLIBRÍ optical observations
  53. GRB 260208A: Mondy optical observations (duplicate submission)
  54. GRB 260208A: Mondy optical observations
  55. GRB 260208A: 1.3m DFOT optical detection
  56. GRB 260208A: COLIBRÍ optical observations
  57. GRB 260208B: EP-FXT observation
  58. GRB 260208A: NOT spectroscopic redshift z = 2.36
  59. GRB 260208A: Liverpool Telescope optical detection
  60. Fermi GRB 260208C: Global MASTER-Net observations report
  61. GRB 260208B: SVOM/VT optical candidate
  62. GRB 260208A: GECAM-B observation of a bright burst
  63. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  64. GRB 260208A: SVOM/VT optical observation
  65. Fermi GRB 260208D: Global MASTER-Net observations report
  66. GRB 260208A: Swift-XRT observations
  67. GRB 260208B: Swift ToO observations
  68. GRB 260208B: SVOM/GRM observation of a bright burst
  69. GRB 260208B: Fermi GBM Detection
  70. GRB 260208B: Fermi-LAT detection
  71. GRB 260208A: Fermi-LAT detection
  72. GRB 260207B: GECAM-B observation
  73. GRB 260208A: Swift ToO observations
  74. GRB 260208A: Fermi GBM Classification Correction
  75. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  76. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  77. Fermi GRB 260208A: Global MASTER-Net observations report
  78. GRB 260207A : MASTER optical counterpart discovery
  79. GRB 260131A/B: Mondy and Terskol optical observations
  80. Fermi GRB 260207B: Global MASTER-Net observations report
  81. GRB 260206A: Swift-XRT observations
  82. EP260131a: VLA detection
  83. GRB 260206A: Tiled Swift observations
  84. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  85. GRB 260204A: Swift-XRT observations
  86. GRB 260204A: LCO optical afterglow detection
  87. GRB 260204A: SVOM/VT optical candidate
  88. GRB 260204A : MASTER Global robotic net optical observations
  89. Fermi GBM Sub-Threshold Detection of GRB 260204A
  90. GRB 260204A: GOTO optical upper limit
  91. GRB 260204A: LCO optical upper limits
  92. EP260110a: Late GTC/EMIR near-infrared observations
  93. GRB 260121A: 239Alferov CubeSat detection
  94. Konus-Wind detection of GRB 260121A
  95. GRB 260131A/B: OHP/T193 optical observations
  96. GRB 260131A: KAIT optical observations
  97. GRB 251230A: MeerLICHT afterglow detection
  98. GRB 260131A: FTW optical and NIR observations
  99. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  100. GRID detection of GRB 260131A/B

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