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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"

3798 results found.

  1. GRB 210427A: BALROG localization (Fermi Trigger / GRB 210427206)
  2. GRB 210427A: Fermi GBM Final Real-time Localization
  3. GRB 210420B: Assy optical observations
  4. GRB 210421A: Swift-BAT refined analysis
  5. GRB 210420B: Swift-XRT refined Analysis
  6. GRB 210420B: DDOTI Detection of the Afterglow
  7. GRB 210420B: Multiband photometry from NOT
  8. GRB 210420B: Optical observations
  9. GRB 210419A: LCO Optical Upper Limit
  10. IceCube Alert 210416.09: Global MASTER-Net observations report
  11. GRB 210413B: Swift/BAT detection and probable localization of a short burst
  12. GRB 210410A: AstroSat CZTI detection
  13. Fermi GRB 210415A: Global MASTER-Net observations report
  14. GRB 210411C: Swift-BAT refined analysis
  15. Fermi GRB 210411A: Global MASTER-Net observations report
  16. Integral GRB210406.72: Global MASTER-Net observations report
  17. GRB 210402A: Swift-BAT refined analysis
  18. Fermi trigger No 639199407: Global MASTER-Net observations report
  19. GRB 210403A: Swift-BAT refined analysis
  20. Fermi GRB 210324B: Global MASTER-Net observations report
  21. MAXI GRB210320.89: Global MASTER-Net observations report
  22. GRB 210320A: MAXI/GSC detection
  23. GRB210318B: Swift detection of a burst
  24. GRB 210312B: Redshift from OSIRIS/GTC
  25. GRB 210312B: GTC photometry
  26. Fermi GRB 210312A: Global MASTER-Net observations report
  27. GRB 210308A: Swift-BAT refined analysis
  28. GRB 210307A: Swift-BAT refined analysis
  29. GRB 210306A: Swift-BAT refined analysis
  30. GRB 210305A: Swift-BAT refined analysis
  31. GRB 210307A: Swift detection of a burst
  32. GRB 210306A: iTelescope T24 optical observations
  33. GRB 210306A: Swift detection of a burst with a bright optical counterpart
  34. GRB 210226A: Swift detection of a burst
  35. Fermi trigger No 635922820: Global MASTER-Net observations report
  36. Konus-Wind detection of GRB 210222A
  37. GRB 210222A: CALET Gamma-Ray Burst Monitor detection
  38. GRB 210222A: MAXI/GSC detection
  39. GRB 210218A: Swift-BAT refined analysis
  40. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued Assy and Mondy optical observations
  41. GRB 210212B (TF21aakruew/AT2021cwd): Assy optical observations
  42. IPN triangulation of GRB 210212B (consistent with ZTF21aakruew/AT2021cwd)
  43. GRB 210211A: Swift/UVOT Detection
  44. GRB 210211A: REM optical/NIR afterglow detection
  45. GRB 210211A: Swift detection of a burst
  46. GRB 210210A: Swift-BAT refined analysis
  47. Fermi GRB 210210B: Global MASTER-Net observations report
  48. Swift GRB 210210A: Global MASTER-Net observations report
  49. GRB 210207B: AstroSat CZTI detection
  50. SGR 1935+2154: MAXI/GSC detection
  51. GRB 210204A: AstroSat CZTI Detection
  52. IPN triangulation of GRB 210204A
  53. GRB 210204: Fermi GBM observation
  54. Fermi trigger No 633879387: Global MASTER-Net observations report
  55. GRB 210120A(MASTER OT J105242.66+152355.0 / AT2021axc): Mondy optical observations
  56. Short Fermi GRB 210119A or new SGR Swift J1851.2-6148: Possible MASTER Short OT detection
  57. Fermi GRB 210119A: Global MASTER-Net observations report
  58. NuEm-210111A: MAXI/GSC upper limit
  59. MAXI GRB210110.64: Global MASTER-Net observations report
  60. GRB 210110A: MAXI/GSC detection
  61. GRB 210109A: MAXI/GSC detection
  62. GRB 201227A: continued Chilescope confirmation of variability of possible optical counterpart, redshift estimating
  63. Fermi trigger No 631602681: Global MASTER-Net observations report
  64. GRB 210102B: further Swift-XRT observations
  65. GRB 210102B: Assy optical afterglow identification
  66. GRB 210104A: iTelescope optical upper limit
  67. GRB 210104B: Swift-BAT refined analysis
  68. GRB 210102B: Tiled Swift observations
  69. GRB 210102B: Assy optical observations
  70. GRB 210102B: Swift-XRT observations
  71. MAXI GRB210102.38: Global MASTER-Net observations report
  72. GRB 210102B: Tiled Swift observations
  73. GRB 210102B: MAXI/GSC detection
  74. INTEGRAL Weak #8913: AROMA-N Optical Observation
  75. Fermi trigger No 631118376: Global MASTER-Net observations report
  76. Fermi trigger No 631104264: Global MASTER-Net observations report
  77. GRB 201104B: Maidanak and CrAO optical observations
  78. GRB 201223A: Mondy and Kitab optical observations
  79. Fermi trigger No 630389391: Global MASTER-Net observations report
  80. GRB 201221D: LCOGT upper limits
  81. Fermi GRB 201218A: Global MASTER-Net observations report
  82. IceCube-201209A : MAXI/GSC upper limit
  83. GRB 201216C: MAGIC detection in very high energy gamma rays
  84. Fermi GRB 201216A: Global MASTER-Net observations report
  85. Fermi GRB 201214B: Global MASTER-Net observations report
  86. IceCube Alert 201209.43: Global MASTER-Net observations report
  87. IceCube-201130A: Optical and NIR Imaging Follow-up by Kanata Telescope
  88. Swift GRB201209.24: Global MASTER-Net observations report
  89. GRB 201203A: DDOTI Observations
  90. IceCube Alert 201130.85: Global MASTER-Net observations report
  91. Baksan Neutrino Observatory Alert 201128.90: Global MASTER-Net observations report
  92. Fermi trigger No 628140709: Global MASTER-Net observations report
  93. AMON IC_HAWC NuEm-201124A: No Neutrino Counterpart detected with ANTARES
  94. INTEGRAL Weak #8831 and #8832: AROMA-N Optical Observation
  95. GRB 201116A: OSN Afterglow Candidate
  96. Fermi trigger No 627198169: Global MASTER-Net observations report
  97. ZTF20acozryr/AT2020yxz (GRB 201103B): Mondy, Kitab, TSHAO optical observations
  98. Fermi trigger No 626247072: Global MASTER-Net observations report
  99. GRB 201104B: Swift/UVOT Detection
  100. GRB 201104A: Fermi GBM observation

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