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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"

28085 results found.

  1. EP260214b: DDOTI Optical Detection
  2. EP260214b: GROWTH-India Telescope optical upper limit
  3. EP260214a: VLT near-infrared observation
  4. EP260214a: NOT optical upper limits
  5. EP260214a: COLIBRÍ optical upper limits
  6. EP260214b: OHP/T120 optical observations
  7. EP260214a: refined analysis of the EP-FXT observation
  8. EP260214b: LCO optical counterpart detection
  9. GRB 260211A: SVOM/VT optical counterpart
  10. EP260214b: COLIBRÍ optical observations
  11. EP260214b: NOT optical counterpart detection
  12. EP260214b: Einstein Probe detection of a fast X-ray transient
  13. EP260214a: Global MASTER-Net observations report
  14. EP260214a: Einstein Probe detection of an X-ray transient
  15. GRB 260212A: AstroSat CZTI detection
  16. GRB 260212A: Fermi GBM Observation
  17. EP260213a: Liverpool Telescope optical upper limits
  18. EP260213a: Global MASTER-Net observations report
  19. EP260213a: COLIBRÍ optical upper limits
  20. EP260213a: Optical upper limits with Kinder observations
  21. EP260213a: Mondy R-band optical upper limit
  22. EP260213a: SVOM/C-GFT upper limit
  23. EP260213a: refined analysis of the EP-FXT observation
  24. EP260213a: Einstein Probe detection of a fast X-ray transient
  25. EP/WXT 01709258378: NOT optical upper limits
  26. GRB 260212A: SVOM/GRM observation of a long burst
  27. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  28. GRB 260211A: EP-FXT follow-up observation
  29. GRB 260211A: SVOM/VT optical observation
  30. GRB 260212A: Glowbug gamma-ray detection
  31. Fermi GRB 260212A: Global MASTER-Net observations report
  32. GRB 260211A: LAST optical upper limit
  33. GRB 260210A: SVOM/GRM observation
  34. Fermi GBM Sub-Threshold Detection of GRB 260211A
  35. GRID detection of GRB 260207B
  36. GRB 260211A: LCO optical upper limits
  37. GRB260131A/B: 3.6m DOT Optical Observations
  38. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  39. Fermi trigger No 792537871: Global MASTER-Net observations report
  40. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  41. EP260209a: COLIBRÍ optical upper limit
  42. Fermi GRB 260210C: Global MASTER-Net observations report
  43. EP260209a: LCO optical upper limits
  44. EP260210a: Global MASTER-Net observations report
  45. EP260210a: refined analysis of the EP-FXT observation
  46. EP260209a: Global MASTER-Net observations report
  47. GRB 260208A: LCO detection of the optical counterpart
  48. EP260209a: Einstein Probe detection of a fast X-ray transient
  49. EP260210a: Optical upper limits with Kinder observations
  50. GRB 260210A: Glowbug gamma-ray detection
  51. GRB 260208C: AstroSat CZTI detection
  52. EP260210a: COLIBRÍ optical upper limit
  53. EP260210a: SVOM/C-GFT upper limit
  54. EP260210a: Einstein Probe detection of an X-ray transient
  55. GRB 260207B: AstroSat CZTI detection
  56. GRB 260208C: SVOM/GRM observation
  57. GRB 260204A: Swift-XRT afterglow detection
  58. GRB 260208B: AstroSat CZTI detection of a bright long burst
  59. GRB260208A: Liverpool Telescope optical follow-up observations
  60. GRB 260208A: Glowbug gamma-ray detection
  61. GRB 260208A: NuSTAR detection of prompt emission
  62. GRB 260208A: Fermi GBM Observation
  63. Fermi GRB 260209A: Global MASTER-Net observations report
  64. GRB 260208B: Swift-XRT observations
  65. GRB 260131A/B: continued Mondy optical observations
  66. GRB 260204A: Swift/UVOT Upper Limits
  67. GRB 260208B: COLIBRÍ optical observations
  68. GRB 260208A: Mondy optical observations
  69. GRB 260208A: 1.3m DFOT optical detection
  70. GRB 260208A: COLIBRÍ optical observations
  71. GRB 260208B: EP-FXT observation
  72. Fermi GRB 260208C: Global MASTER-Net observations report
  73. GRB 260208B: SVOM/VT optical candidate
  74. GRB 260208A: GECAM-B observation of a bright burst
  75. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  76. GRB 260208A: SVOM/VT optical observation
  77. Fermi GRB 260208D: Global MASTER-Net observations report
  78. GRB 260208A: Swift-XRT observations
  79. GRB 260208B: SVOM/GRM observation of a bright burst
  80. GRB 260208B: Fermi GBM Detection
  81. LAT GRB 260208B: Global MASTER-Net observations report
  82. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  83. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  84. Fermi GRB 260208A: Global MASTER-Net observations report
  85. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  86. GRB 260131A/B: Mondy and Terskol optical observations
  87. Fermi GRB 260207B: Global MASTER-Net observations report
  88. GRB 260206A: Swift-XRT observations
  89. Fermi trigger No 792135758: Global MASTER-Net observations report
  90. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  91. GRB 260204A: Swift-XRT observations
  92. GRB 260204A: SVOM/VT optical candidate
  93. GRB 260204A : MASTER Global robotic net optical observations
  94. Fermi GBM Sub-Threshold Detection of GRB 260204A
  95. GRB 260204A: LCO optical upper limits
  96. EP260110a: Late GTC/EMIR near-infrared observations
  97. GRB 260121A: 239Alferov CubeSat detection
  98. GRB 260131A: KAIT optical observations
  99. GRB 251230A: MeerLICHT afterglow detection
  100. GRB 260131A/B: GTC/OSIRIS+ redshift confimation

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