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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"

28684 results found.

  1. IceCube-200929A: No significant detection in HAWC
  2. GRB 201001A: Swift-BAT refined analysis
  3. GRB 201001A: Swift-XRT refined Analysis
  4. GRB 201001A: Fermi GBM observation
  5. Swift-XRT observations of IceCube 200929A
  6. Fermi-LAT Gamma-ray Observations of IceCube-200929A
  7. IceCube-200929A: Upper limits from Fermi-GBM Observations
  8. IceCube-200929A: No neutrino counterpart candidates in ANTARES search
  9. IceCube-200926B: No significant detection in HAWC
  10. GRB 200928B: Insight-HXMT/HE detection
  11. IceCube-200926B: Upper limits from Fermi-GBM Observations
  12. IceCube-200926A: Upper limits from Fermi-GBM Observations
  13. IceCube-200926A: No significant detection in HAWC
  14. Fermi GRB 200929A: Global MASTER-Net observations report
  15. GRB 200928B: AstroSat CZTI detection
  16. IceCube-200926A: No Candidate Counterparts from the Zwicky Transient Facility
  17. Fermi-LAT Gamma-ray Observations of IceCube-200926B
  18. IceCube-200926B: No neutrino counterpart candidates in ANTARES search
  19. Swift-XRT observations of IceCube 200926A
  20. Konus-Wind detection of GRB 200920B
  21. Fermi-LAT Gamma-ray Observations of IceCube-200926A
  22. GRB 200925B: Swift-XRT refined analysis update
  23. GRB 200925B NUTTelA-TAO / BSTI Early Measurements (Preliminary)
  24. GRB 200925B: Swift-XRT refined Analysis
  25. GRB 200925B: Swift/UVOT Detection
  26. GRB 200925B: Swift-BAT refined analysis
  27. GRB 200922A: Chilescope optical observations
  28. Swift GRB 200925B: Global MASTER-Net OT detection
  29. GRB 200925B: OSN Afterglow Candidate Discovery
  30. Fermi GRB 200925A: Global MASTER-Net observations report
  31. Konus-Wind observation of GRB 200914A
  32. Fermi GRB 200924A: Global MASTER-Net observations report
  33. GRB 200922A: chance superposition between optical afterglow and archival star
  34. GRB 200922A: Insight-HXMT/HE detection
  35. Fermi GRB 200923A: Global MASTER-Net observations report
  36. GRB 200922A: Swift-BAT refined analysis
  37. Improved enhanced Swift-XRT position of GRB 200922A
  38. GRB 200922A: Swift/UVOT Detection
  39. Fermi-LAT Gamma-ray Observations of IceCube-200921A and detection of a new gamma-ray source, Fermi J1256.9+2630
  40. IceCube-200921A: no significant detection in HAWC observations
  41. Fermi GRB 200922B: Global MASTER-Net observations report
  42. GRB 200922A: LCO observations
  43. Swift GRB 200922A: Global MASTER-Net observations report
  44. GRB 200922A: Swift-XRT refined Analysis
  45. GRB 200917A: Swift/UVOT Upper Limits
  46. GRB 200919C: Insight-HXMT/HE detection
  47. IceCube-200921A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  48. IceCube-200921A: Upper limits from Fermi-GBM Observations
  49. IPN triangulation of GRB 200920B (short)
  50. GRB 200914A: Swift-XRT further observations
  51. IceCube-200916A - ZTF20acaapwk/SN2020tno classified as SN Ia
  52. Fermi GRB 200919C: Global MASTER-Net observations report
  53. GRB 200919A: CrAO/ZTSh early optical upper limit
  54. Fermi GRB 200919B: Global MASTER-Net observations report
  55. GRB 200919A: Swift-BAT refined analysis
  56. GRB 200916B: MASTER optical observation
  57. IceCube-200916A: AbAO observations of optical candidates ZTF20acaapwk/AT2020tno, ZTF20acaapwo/AT2020tnp
  58. GRB 200916B: AstroSat CZTI detection
  59. GRB 200917A: GROWTH-India Telescope optical upper limit.
  60. Swift-XRT observations of IceCube 200916A
  61. IceCube-200916A: No significant detection in HAWC
  62. GRB 200917A: Swift-BAT refined analysis
  63. IceCube-200916A: No neutrino counterpart candidates in ANTARES search
  64. Fermi-GBM Sub-Threshold Detection of GRB 200917A
  65. GRB 200917A: Swift-XRT refined Analysis
  66. IceCube-200916A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  67. Swift GRB 200917A: Global MASTER-Net observations report
  68. IceCube-200916A: Two Candidate Counterparts from the Zwicky Transient Facility
  69. IPN triangulation of GRB 200916B (short)
  70. IceCube-200916A: Upper limits from Fermi-GBM Observations
  71. Fermi-LAT Gamma-ray Observations of IceCube-200916A
  72. Swift-XRT observations of IceCube 200911A
  73. Fermi GRB 200916A: Global MASTER-Net observations report
  74. Fermi GRB 200914A: Global MASTER-Net observations report
  75. GRB 200914A: AGILE detection
  76. GRB 200914A: Swift-XRT observations
  77. GRB 200914A: Fermi GBM observation
  78. IceCube-200911A: No significant detection in HAWC
  79. Fermi-LAT Gamma-ray Observations of IceCube-200911A and detection of a new gamma-ray source, Fermi J0330.1+3743
  80. GRB 200914A: Swift ToO observations
  81. IceCube-200911A: No neutrino counterpart candidates in ANTARES search
  82. IceCube-200911A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  83. IceCube-200911A: not observable by Fermi-GBM
  84. GRB 200826A: uGMRT radio upper limit at 1.25 GHz
  85. IPN triangulation of GRB 200907A (short)
  86. GRB 200909B: Swift-BAT refined analysis
  87. GRB 200909A: AstroSat CZTI detection
  88. GRB 200829A: T100 observations
  89. Fermi GRB 200909A: Global MASTER-Net observations report
  90. GRB 200907B: Swift/UVOT Upper Limits
  91. Fermi GRB 200908A: Global MASTER-Net observations report
  92. GRB 200907B: Swift-BAT refined analysis
  93. Konus-Wind detection of GRB 200903E
  94. GRB 200907B: AstroSat CZTI detection
  95. GRB 200907B: Swift-XRT refined Analysis
  96. GRB 200907B: MITSuME Okayama optical upper limits
  97. Swift GRB 200907B: Global MASTER-Net observations report
  98. Fermi GRB 200907C: Global MASTER-Net observations report
  99. Correction to GCN 28387: GRB 200907B GROWTH-India optical upper limit
  100. GRB200907A: GROWTH-India optical upper limit

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