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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"

32491 results found.

  1. GRB 230228A: Swift-BAT refined analysis
  2. GRB 230228A: Swift/UVOT Upper Limits
  3. Fermi GRB 230301B: Global MASTER-Net observations report
  4. GRB 230228A: Fermi GBM Observation
  5. GRB 230228A: OSN optical upper limit
  6. GRB 230228A: Swift-XRT refined Analysis
  7. GRB 230228A: Mondy optical upper limit
  8. GRB 230228A: Nanshan/NEXT optical upper limit
  9. GRB 230228A: Miryang Arirang Astronomical Observatory (MAAO) 0.7-m telescope optical upper limit
  10. Fermi GRB 230227A: Global MASTER-Net observations report
  11. GRB 230217A: VLT/FORS2 optical observations and candidate counterpart
  12. GRB 230216A Mondy Observations
  13. GRB 230205A: VLA radio afterglow confirmation
  14. GRB 230217A: Swift/UVOT Upper Limits
  15. GRB 230216A: Swift/UVOT Upper Limits
  16. GRB 230217A: Continued Gemini Observations
  17. GRB 230220A: Correction to GCN 33352
  18. GRB 230217A: Swift-XRT afterglow detection
  19. Fermi-LAT gamma-ray observations of IceCube-230220A
  20. GRB 230217A: Swift-BAT refined analysis
  21. Fermi GRB 230220B: Global MASTER-Net observations report
  22. GRB 230217A: AstroSat CZTI detection
  23. GRB 230217A: Gemini South optical upper limits
  24. GRB 230216B: CALET Gamma-Ray Burst Monitor detection
  25. GRB 230217A: 6 GHz VLA observations
  26. GRB 230217A: Gemini-South Optical Observation
  27. GRB 230217A: Fermi GBM observation
  28. IceCube-230217A: BOOTES-4/MET Optical Observations
  29. Fermi-LAT gamma-ray observations of IceCube-230217A
  30. Konus-Wind detection of GRB 230217A
  31. GRB 230217A: Swift-XRT observations
  32. GRB 230218A is not a GRB
  33. GRB 230217A: AGILE/MCAL detection
  34. GRB 230207B: CALET Gamma-Ray Burst Monitor detection
  35. GRB 230216B: AstroSat CZTI detection
  36. GRB 230216A: SVOM/C-GFT optical upper limit
  37. GRB 230216A: Swift-BAT refined analysis
  38. GRB 230216A: Swift-XRT refined Analysis
  39. GRB 230205A: Lowell Discovery Telescope Observations
  40. GRB 230204B: Lowell Discovery Telescope Observations
  41. Swift GRB 230216A: Global MASTER-Net observations report
  42. GRB 230216A: AKO Upper Limit
  43. GRB 230216A: Zadko observatory - Gingin optical observations
  44. Fermi GRB 230215A: Global MASTER-Net observations report
  45. GRB 230209B: AGILE detection
  46. GRB 230209B: Fermi GBM Observation
  47. IPN triangulation of GRB 230209B
  48. GRB 230204B: CALET Gamma-Ray Burst Monitor detection
  49. GRB 230204B: ATCA radio detection
  50. Outburst from LS V +44 17 / RX J0440.9+4431: Transient detection by GRBAlpha
  51. 230211A is not a GRB
  52. GRB 230209B: Swift/BAT-GUANO detection outside the coded FOV
  53. Fermi GRB 230209B: Global MASTER-Net observations report
  54. GRB 230205A: 6 GHz VLA observations
  55. GRB 230209A is not a GRB
  56. GRB 230205A: SUBARU HSC pre-imaging for host galaxy search
  57. GRB 221009A: Continued Swift Observations
  58. GRB 230207B: Detection by GRBAlpha
  59. GRB 230205A: possible host galaxy detection with the Schmidt - Asiago telescope
  60. GRB 230204B: MASTER early OT detection
  61. GRB 230207B: Swift/BAT-GUANO detection outside the coded FOV
  62. ZTF23aabmzlp/AT2023azs: Neil Gehrels Swift Observatory X-ray observations
  63. Fermi GRB 230207A: Global MASTER-Net observations report
  64. GRB 230204B: LCOGT Optical Upper Limits
  65. GRB 230204B: Swift/UVOT Upper Limits
  66. GRB 230205A: Swift/UVOT Upper Limits
  67. GRB 230204B: Fermi GBM detection
  68. Fermi Gamma-ray Burst Monitor triggers due to recent activity of RX J0440.9+4431 (LS V +44 17)
  69. GRB 230205A: LCOGT Optical Upper Limits
  70. GRB 230204B: Swift-XRT afterglow detection
  71. GRB 230204B: 3.6m DOT optical observation
  72. GRB 230205A: SVOM/C-GFT optical upper limit
  73. GRB 230205A: OHP/T193 optical observations
  74. GRB 230204B: VLT/X-shooter redshift
  75. GRB 230205A: Swift-BAT refined analysis (T90 = 2.3 s)
  76. GRB 230204A: Swift-BAT refined analysis
  77. GRB 230204B: ATLAS detection of the optical afterglow and a projected location in a nearby galaxy group
  78. GRB 230205A: Swift-XRT refined Analysis
  79. GRB 230204B: Swift ToO observations
  80. GRB 230204B: Detection by GRBAlpha
  81. IceCube-230201A: BOOTES-4/MET Optical Upper Limits
  82. GRB 230204B: GIT discovery of the likely optical afterglow
  83. GRB 230204B: AstroSat CZTI detection
  84. GRB 230204B: Swift/BAT-GUANO detection outside the coded FOV
  85. GRB 230204A: Swift/UVOT Upper Limits
  86. GRB 230204A: Swift-XRT refined Analysis
  87. GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate
  88. GRB 230201B: TURBO Optical Upper Limits
  89. ZTF23aabmzlp/AT2023azs: Lulin 1m LOT optical observations
  90. GRB 221216A: Swift-BAT refined analysis
  91. ZTF23aabmzlp/AT2023azs: VLA radio detection
  92. ZTF23aaarlti/AT2023avj: AMI-LA radio detection
  93. ZTF23aabmzlp/AT2023azs: AMI-LA radio upper limit
  94. Fermi GRB 230201B: Global MASTER-Net observations report
  95. Fermi-LAT gamma-ray observations of IceCube-230201A
  96. GRB 230126A: Detection by VZLUSAT-2
  97. Fermi GRB 230201A: Global MASTER-Net observations report
  98. GRB 221009A: radio afterglow detection with the EVN
  99. ZTF23aabmzlp/AT2023azs: LCOGT Optical Detection
  100. ZTF23aaarlti/AT2023avj: Assy continued optical observations

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