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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"

28677 results found.

  1. IceCube-200929A: No neutrino counterpart candidates in ANTARES search
  2. IceCube-200926B: No significant detection in HAWC
  3. GRB 200928B: Insight-HXMT/HE detection
  4. IceCube-200926B: Upper limits from Fermi-GBM Observations
  5. IceCube-200926A: Upper limits from Fermi-GBM Observations
  6. IceCube-200926A: No significant detection in HAWC
  7. Fermi GRB 200929A: Global MASTER-Net observations report
  8. GRB 200928B: AstroSat CZTI detection
  9. IceCube-200926A: No Candidate Counterparts from the Zwicky Transient Facility
  10. Fermi-LAT Gamma-ray Observations of IceCube-200926B
  11. IceCube-200926B: No neutrino counterpart candidates in ANTARES search
  12. Swift-XRT observations of IceCube 200926A
  13. Konus-Wind detection of GRB 200920B
  14. Fermi-LAT Gamma-ray Observations of IceCube-200926A
  15. GRB 200925B: Swift-XRT refined analysis update
  16. GRB 200925B NUTTelA-TAO / BSTI Early Measurements (Preliminary)
  17. GRB 200925B: Swift-XRT refined Analysis
  18. GRB 200925B: Swift/UVOT Detection
  19. GRB 200925B: Swift-BAT refined analysis
  20. GRB 200922A: Chilescope optical observations
  21. Swift GRB 200925B: Global MASTER-Net OT detection
  22. GRB 200925B: OSN Afterglow Candidate Discovery
  23. Fermi GRB 200925A: Global MASTER-Net observations report
  24. Konus-Wind observation of GRB 200914A
  25. Fermi GRB 200924A: Global MASTER-Net observations report
  26. GRB 200922A: chance superposition between optical afterglow and archival star
  27. GRB 200922A: Insight-HXMT/HE detection
  28. Fermi GRB 200923A: Global MASTER-Net observations report
  29. GRB 200922A: Swift-BAT refined analysis
  30. Improved enhanced Swift-XRT position of GRB 200922A
  31. GRB 200922A: Swift/UVOT Detection
  32. Fermi-LAT Gamma-ray Observations of IceCube-200921A and detection of a new gamma-ray source, Fermi J1256.9+2630
  33. IceCube-200921A: no significant detection in HAWC observations
  34. Fermi GRB 200922B: Global MASTER-Net observations report
  35. GRB 200922A: LCO observations
  36. Swift GRB 200922A: Global MASTER-Net observations report
  37. GRB 200922A: Swift-XRT refined Analysis
  38. GRB 200917A: Swift/UVOT Upper Limits
  39. GRB 200919C: Insight-HXMT/HE detection
  40. IceCube-200921A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  41. IceCube-200921A: Upper limits from Fermi-GBM Observations
  42. IPN triangulation of GRB 200920B (short)
  43. GRB 200914A: Swift-XRT further observations
  44. IceCube-200916A - ZTF20acaapwk/SN2020tno classified as SN Ia
  45. Fermi GRB 200919C: Global MASTER-Net observations report
  46. GRB 200919A: CrAO/ZTSh early optical upper limit
  47. Fermi GRB 200919B: Global MASTER-Net observations report
  48. GRB 200919A: Swift-BAT refined analysis
  49. GRB 200916B: MASTER optical observation
  50. IceCube-200916A: AbAO observations of optical candidates ZTF20acaapwk/AT2020tno, ZTF20acaapwo/AT2020tnp
  51. GRB 200916B: AstroSat CZTI detection
  52. GRB 200917A: GROWTH-India Telescope optical upper limit.
  53. Swift-XRT observations of IceCube 200916A
  54. IceCube-200916A: No significant detection in HAWC
  55. GRB 200917A: Swift-BAT refined analysis
  56. IceCube-200916A: No neutrino counterpart candidates in ANTARES search
  57. Fermi-GBM Sub-Threshold Detection of GRB 200917A
  58. GRB 200917A: Swift-XRT refined Analysis
  59. IceCube-200916A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  60. Swift GRB 200917A: Global MASTER-Net observations report
  61. IceCube-200916A: Two Candidate Counterparts from the Zwicky Transient Facility
  62. IPN triangulation of GRB 200916B (short)
  63. IceCube-200916A: Upper limits from Fermi-GBM Observations
  64. Fermi-LAT Gamma-ray Observations of IceCube-200916A
  65. Swift-XRT observations of IceCube 200911A
  66. Fermi GRB 200916A: Global MASTER-Net observations report
  67. Fermi GRB 200914A: Global MASTER-Net observations report
  68. GRB 200914A: AGILE detection
  69. GRB 200914A: Swift-XRT observations
  70. GRB 200914A: Fermi GBM observation
  71. IceCube-200911A: No significant detection in HAWC
  72. Fermi-LAT Gamma-ray Observations of IceCube-200911A and detection of a new gamma-ray source, Fermi J0330.1+3743
  73. GRB 200914A: Swift ToO observations
  74. IceCube-200911A: No neutrino counterpart candidates in ANTARES search
  75. IceCube-200911A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  76. IceCube-200911A: not observable by Fermi-GBM
  77. GRB 200826A: uGMRT radio upper limit at 1.25 GHz
  78. IPN triangulation of GRB 200907A (short)
  79. GRB 200909B: Swift-BAT refined analysis
  80. GRB 200909A: AstroSat CZTI detection
  81. GRB 200829A: T100 observations
  82. Fermi GRB 200909A: Global MASTER-Net observations report
  83. GRB 200907B: Swift/UVOT Upper Limits
  84. Fermi GRB 200908A: Global MASTER-Net observations report
  85. GRB 200907B: Swift-BAT refined analysis
  86. Konus-Wind detection of GRB 200903E
  87. GRB 200907B: AstroSat CZTI detection
  88. GRB 200907B: Swift-XRT refined Analysis
  89. GRB 200907B: MITSuME Okayama optical upper limits
  90. Swift GRB 200907B: Global MASTER-Net observations report
  91. Fermi GRB 200907C: Global MASTER-Net observations report
  92. Correction to GCN 28387: GRB 200907B GROWTH-India optical upper limit
  93. GRB200907A: GROWTH-India optical upper limit
  94. Fermi GRB 200906A: Global MASTER-Net observations report
  95. IPN triangulation of GRB 200903E
  96. GRB 200906A: EMIR/GTC NIR upper limit
  97. GRB 200906A: LBT near-infrared upper limit
  98. GRB 200906A: Swift-BAT refined analysis
  99. GRB 200906A: Swift/UVOT Upper Limits
  100. GRB 200906A: GROWTH-India Telescope (GIT) optical r band upper limit

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