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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"

28679 results found.

  1. Swift GRB 201203A: Global MASTER-Net observations report
  2. GRB 201203A: Swift-XRT afterglow detection
  3. IceCube-201130A: No Candidate Counterparts from the Zwicky Transient Facility
  4. GRB 201203A: KAIT Optical Upper Limit
  5. GRB 201203A: DDOTI Observations
  6. IceCube-201130A: No significant detection in HAWC
  7. IceCube-201130A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  8. GRB201130A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 628407054)
  9. GRB 201128B: Swift-XRT observations
  10. Swift observations of the Fermi-LAT source 4FGL J0206.4-1151 in the error region of IceCube-201130A
  11. Fermi-LAT Gamma-ray Observations of IceCube-201130A
  12. IceCube-201130A: Not observable by Fermi-GBM
  13. GRB 201201A: DDOTI Observations
  14. Fermi GRB 201201A: Global MASTER-Net observations report
  15. GRB 201128B: Swift ToO observations
  16. Swift-XRT observations of IceCube 201130A
  17. GRB 201128B: Swift/BAT-GUANO detection and arcminute localization
  18. GRB 201128A: Swift/UVOT Upper Limits
  19. GRB 201130A: DDOTI Observations
  20. Fermi GRB 201130A: Global MASTER-Net observations report
  21. GRB 201128A: Swift-BAT refined analysis
  22. GRB 201128A: Swift-XRT refined Analysis
  23. GRB 201128A: DDOTI Observations
  24. IceCube-201114A: Updated photometry for three DECam candidate optical counterparts
  25. GRB 201121A: Insight-HXMT/HE detection
  26. AMON IC_HAWC NuEm-201124A: No Neutrino Counterpart detected with ANTARES
  27. IceCube-201120A in the Cygnus region: No enhanced TeV gamma-ray flux detected by HAWC
  28. GRB 200826A: TNG and LBT constraints on a supernova bump
  29. IceCube-201114A: DECam observations and candidate optical counterpart
  30. GRB 201015A L-band observations with e-MERLIN
  31. Fermi-LAT Gamma-ray Observations of IceCube-201120A
  32. IceCube-201120A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  33. IceCube-201120A: Swift-XRT non-detection of 4FGL J2028.6+4110e
  34. GRB 201015A radio afterglow with e-MERLIN
  35. Fermi GRB 201121A: Global MASTER-Net observations report
  36. Fermi GRB 201120B: Global MASTER-Net observations report
  37. IceCube-201120A: Upper limits from Fermi-GBM Observations
  38. ZTF20acozryr/AT2020yxz (GRB 201103B): SAO RAS optical observations
  39. ZTF20acozryr/AT2020yxz (GRB 201103B): correction to the GCN #28883 CrAO/ZTSh optical observations
  40. IceCube 201114A: Swift followup of Fermi J0703.5+0505
  41. GRB 201116A: CALET Gamma-Ray Burst Monitor detection
  42. Konus-Wind detection of GRB 201116A
  43. Fermi-LAT Gamma-ray Observations of IceCube-201114A
  44. GRB 201116A: NOT optical observations
  45. GRB 201116A: Swift-XRT afterglow detection
  46. GRB 201116A: OSN Afterglow Candidate
  47. Swift Trigger 1006917 is Be/X-ray binary pulsar 1A 0535+262
  48. IceCube-201115A: No significant detection in HAWC
  49. IceCube-201114A: No significant detection in HAWC
  50. GRB 201116A: Fermi-LAT detection
  51. GRB 201116A: Tiled Swift observations
  52. IceCube-201115A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  53. IceCube-201114A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  54. IceCube-201115A: No neutrino counterpart candidates in ANTARES search
  55. Fermi-LAT Gamma-ray Observations of IceCube-201115A
  56. IceCube-201115A: not observable by Fermi-GBM
  57. Swift XRT observations of the Fermi-LAT source 4FGL J0658.6+0636, positionally consistent with the IceCube high-energy neutrino alert
  58. IceCube-201114A: Upper limits from Fermi GBM Observations
  59. VLASS identifies possible radio counterparts to IceCube-201115A, including a bright BL Lac candidate
  60. IceCube GCN alert 134701_49508272.amon retraction
  61. Swift-XRT observations of IceCube 201114A
  62. IceCube-201114A: No neutrino counterpart candidates in ANTARES search
  63. ZTF20acozryr/AT2020yxz (GRB 201103B): CrAO/ZTSh optical observations
  64. Fermi-LAT Gamma-ray Observations of NuEm-201107A
  65. ZTF20acozryr/AT2020yxz (GRB 201103B): Mondy continued optical observations
  66. Fermi GRB 201111A: Global MASTER-Net observations report
  67. Konus-Wind observation of GRB 201109A
  68. ZTF20acozryr/AT2020yxz (GRB 201103B): Flattening of the optical light curve
  69. Swift Trigger 1005428: Detection of SGR 1830-0645
  70. IPN triangulation of GRB 201109A (short)
  71. ZTF20acozryr (GRB 201103B): GROWTH-India Telescope optical observations
  72. ZTF20acozryr/AT2020yxz (GRB 201103B): Mondy, Kitab, TSHAO optical observations
  73. GRB 201109A: Fermi GBM detection
  74. GRB 201104A: AstroSat CZTI detection
  75. Konus-Wind observation of GRB 201103B
  76. GRB 201104B: continued TSHAO optical observation
  77. GRB 201104B: MITSuME Akeno optical observation
  78. Fermi GRB 201109A: Global MASTER-Net observations report
  79. Fermi GRB 201108A: Global MASTER-Net observations report
  80. Konus-Wind detection of GRB 201105A
  81. ZTF20acozryr/AT2020yxz (GRB 201103B): Assy optical observations
  82. GRB 201104B: 1.3m DFOT optical observations
  83. GRB 201104A: Swift-XRT observations
  84. Swift XRT and UVOT detection of ZTF20acozryr/AT2020yxz/GRB201103B
  85. GRB 201015A: Swift-XRT late time observations
  86. GRB 201104B: Kitab optical observations
  87. Correction to GCN 28843: GBM report of GRB 201105B should have been GRB 201105A
  88. GRB 201103B (ZTF20acozryr/AT2020yxz): Xinglong-2.16m optical observations
  89. GRB 201104B: TSHAO optical observation
  90. GRB 201104B: Swift/UVOT Detection
  91. GRB 201104B: Swift-XRT refined Analysis
  92. Correcton to GCN 28848: Swift observes ZTF20acozryr
  93. GRB 201104C: Swift ToO observations
  94. GRB 201103B (ZTF20acozryr/AT2020yxz): VLT/X-shooter redshift
  95. GRB 201103B (ZTF20acozryr/AT2020yxz): Nanshan/NEXT-0.6m optical observations
  96. GRB 201105A: Swift detected burst and BAT refined analysis
  97. IPN triangulation of GRB 201103B (consistent with ZTF20acozryr/AT2020yxz)
  98. ZTF20acozryr/AT2020yxz: Zwicky Transient Facility discovery of a fast optical transient with no associated GRB
  99. GRB 201104B: VLT/X-shooter redshift
  100. GRB 201104B: Swift-BAT refined analysis

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