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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"

21793 results found.

  1. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  2. EP260221a: GOTO optical upper limit
  3. Fermi GRB 260219A: Global MASTER-Net observations report
  4. SVOM alert sb26021801: LAST optical upper limit
  5. IceCube Alert 260217A: Global MASTER-Net observations report
  6. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  7. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  8. sb26021801: SVOM detection of a long faint X-ray transient
  9. EP-WXT 01709258455: NOT optical upper limits
  10. EP260214b: Mondy optical observations
  11. EP260214b: 1.3m DFOT optical upper limit
  12. EP260210a: Mondy optical upper limits
  13. GRB 260208A: continued Mondy optical observations
  14. EP260214b: Liverpool Telescope optical observations
  15. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  16. EP260214b: Optical upper limit with Kinder observations
  17. EP260214a: Optical upper limits with Kinder observations
  18. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  19. EP260214b: DDOTI Optical Detection
  20. EP260214b: GROWTH-India Telescope optical upper limit
  21. EP260214a: VLT near-infrared observation
  22. EP260214a: NOT optical upper limits
  23. EP260214b: OHP/T120 optical observations
  24. EP260214a: refined analysis of the EP-FXT observation
  25. EP260214b: LCO optical counterpart detection
  26. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  27. GRB 260211A: SVOM/VT optical counterpart
  28. EP260214b: COLIBRÍ optical observations
  29. EP260214b: NOT optical counterpart detection
  30. EP260214a: Global MASTER-Net observations report
  31. EP260213a: Global MASTER-Net observations report
  32. EP260213a: Optical upper limits with Kinder observations
  33. EP260213a: NUTTelA-TAO Early Optical Limits
  34. EP260213a: SVOM/C-GFT upper limit
  35. EP260213a: refined analysis of the EP-FXT observation
  36. EP/WXT 01709258378: NOT optical upper limits
  37. GRB 260211A - SVOM/ECLAIRs refined analysis
  38. GRB 260204A: SVOM/ECLAIRs refined analysis
  39. GRB 260211A: GOTO optical upper limit
  40. Fermi GRB 260212A: Global MASTER-Net observations report
  41. GRB 260211A: LAST optical upper limit
  42. Fermi GBM Sub-Threshold Detection of GRB 260211A
  43. GRB 260128B: SVOM/ECLAIRs refined analysis
  44. GRB260131A/B: 3.6m DOT Optical Observations
  45. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  46. Fermi trigger No 792537871: Global MASTER-Net observations report
  47. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  48. GRB 260208A: Swift UVOT detection
  49. Fermi GRB 260210C: Global MASTER-Net observations report
  50. EP260209a: LCO optical upper limits
  51. EP260210a: Global MASTER-Net observations report
  52. EP260210a: refined analysis of the EP-FXT observation
  53. EP260209a: Global MASTER-Net observations report
  54. GRB 260208A: LCO detection of the optical counterpart
  55. EP260210a: Optical upper limits with Kinder observations
  56. EP260210a: SVOM/C-GFT upper limit
  57. GRB 260204A: Swift-XRT afterglow detection
  58. GRB260208A: Liverpool Telescope optical follow-up observations
  59. Fermi GRB 260209A: Global MASTER-Net observations report
  60. GRB 260208B: Swift-XRT observations
  61. GRB 260131A/B: continued Mondy optical observations
  62. GRB 260204A: Swift/UVOT Upper Limits
  63. GRB 260208B: COLIBRÍ optical observations
  64. GRB 260208A: Mondy optical observations (duplicate submission)
  65. GRB 260208A: Mondy optical observations
  66. GRB 260208A: 1.3m DFOT optical detection
  67. GRB 260208A: COLIBRÍ optical observations
  68. GRB 260208A: NOT spectroscopic redshift z = 2.36
  69. GRB 260208A: Liverpool Telescope optical detection
  70. Fermi GRB 260208C: Global MASTER-Net observations report
  71. GRB 260208B: SVOM/VT optical candidate
  72. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  73. GRB 260208A: SVOM/VT optical observation
  74. Fermi GRB 260208D: Global MASTER-Net observations report
  75. GRB 260208A: Swift-XRT observations
  76. GRB 260208B: Swift ToO observations
  77. LAT GRB 260208B: Global MASTER-Net observations report
  78. GRB 260208A: Swift ToO observations
  79. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  80. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  81. Fermi GRB 260208A: Global MASTER-Net observations report
  82. GRB 260207A : MASTER optical counterpart discovery
  83. GRB 260131A/B: Mondy and Terskol optical observations
  84. Fermi GRB 260207B: Global MASTER-Net observations report
  85. GRB 260206A: Swift-XRT observations
  86. Fermi trigger No 792135758: Global MASTER-Net observations report
  87. EP260131a: VLA detection
  88. GRB 260206A: Tiled Swift observations
  89. GRB 260204A: Swift-XRT observations
  90. GRB 260204A: LCO optical afterglow detection
  91. GRB 260204A : MASTER Global robotic net optical observations
  92. Fermi GBM Sub-Threshold Detection of GRB 260204A
  93. GRB 260204A: GOTO optical upper limit
  94. EP260110a: Late GTC/EMIR near-infrared observations
  95. GRB 260204A: SVOM detection of a burst
  96. GRB 260121A: 239Alferov CubeSat detection
  97. GRB 260131A/B: OHP/T193 optical observations
  98. GRB 260131A: KAIT optical observations
  99. GRB 251230A: MeerLICHT afterglow detection
  100. GRB 260131A: FTW optical and NIR observations

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