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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"
  1. IPN triangulation of GRB 210204A
  2. GRB 210205A: Swift-XRT refined Analysis
  3. GRB 210205A: MITSuME Ishigaki optical observation
  4. ZTF21aagwbjr/AT2021buv: ZTF discovery of a fast optical transient likely associated with GRB 210104A
  5. GRB 210205B: AGILE/MCAL detection of a burst
  6. GRB 210205A: Swift/UVOT Upper Limits
  7. Swift GRB 210205A: Global MASTER-Net observations report
  8. GRB 210205A: Nanshan/NEXT optical upper limit
  9. GRB 210205A: BOOTES-4/MET optical upper limit
  10. GRB 210205A: Enhanced Swift-XRT position
  11. GRB 210205A： GWAC-F60A optical upper limit
  12. GRB 210205A: Swift detection of a burst
  13. Fermi GRB 210204B: Global MASTER-Net observations report
  14. Fermi GRB 210204A: Global MASTER-Net observations report
  15. GRB 210204B: Fermi GBM Final Real-time Localization
  16. GRB 210204: Fermi GBM observation
  17. GRB 210204A: GECAM detection
  18. GRB 210204A: BALROG localization (Fermi Trigger 634112970 / GRB 210204270)
  19. GRB 210204A: Fermi GBM Final Real-time Localization
  20. GRB 210202A: AGILE/MCAL detection
  21. Fermi GBM Observations of a bright burst from SGR J1935+2154
  22. GRB 210202A: Fermi GBM detection
  23. GRB 210202A: Fermi-LAT detection
  24. Fermi GRB 210202A: Global MASTER-Net observations report
  25. Fermi trigger No 633963272: Global MASTER-Net observations report
  26. Recent activity of SGR 1935+2154 as observed by CGBM
  27. GRB 210202A: BALROG localization (Fermi Trigger / GRB 210202841)
  28. INTEGRAL detection of a short burst from SGR 1935+2154
  29. GRB 210202A: Fermi GBM Final Real-time Localization
  30. GRB 210131A: GECAM detection
  31. Fermi trigger No 633879387: Global MASTER-Net observations report
  32. GECAM observations of SGR 1935+2154
  33. GRB 210129A: Insight-HXMT/HE detection
  34. Continued Chandra observations of GW170817 at ~3.3 years since merger
  35. Fermi GBM Observations of SGR J1935+2154
  36. Konus-Wind detection of two bright bursts from SGR 1935+2154
  37. GRB 140330A: Swift-XRT refined Analysis
  38. GRB 140320B: Swift-XRT refined Analysis
  39. GRB 140402A: Swift-XRT refined Analysis
  40. GRB 140104B: Swift-XRT refined Analysis
  41. GRB 210126A: AstroSat CZTI detection
  42. GRB 210124B: AstroSat CZTI detection
  43. GRB 210123A: AstroSat CZTI detection
  44. IPN triangulation of a bright burst from SGR 1935+2154
  45. ZTF21aaeyldq: Observations with the 3.6m DOT
  46. GECAM detection of a short burst probably from SGR 1935+2154
  47. GRB 210127A: Fermi GBM Final Real-time Localization
  48. GRB 210120A: Fermi GBM detection
  49. Fermi trigger No 633348010: Global MASTER-Net observations report
  50. HAWC Transient event on 2021/01/25
  51. Konus-Wind detection of GRB 210121A
  52. Konus-Wind detection of GRB 210124B
  53. GRB 210126A: GECAM detection
  54. IPN triangulation of GRB 210124B (short)
  55. GRB 210126A: BALROG localization (Fermi Trigger / GRB 210126417)
  56. GRB 210124B: Insight-HXMT/HE detection
  57. Fermi trigger No 633257525: Global MASTER-Net observations report
  58. GRB 210123A: Fermi GBM Final Localization
  59. GECAM detection of a burst possibly from the X-ray burster 4U 0614+09 or GRB 210124A
  60. GRB 210123A: Insight-HXMT/HE detection
  61. IPN triangulation of GRB 210121A
  62. GRB 210121A: GECAM detection
  63. GRB 210121A: Insight-HXMT/HE detection
  64. GRB 210120A : 1.3m DFOT optical observations
  65. ZTF21aaeyldq: GROND and CAHA jet break confirmation
  66. ZTF20aaeyldq: VLA radio detection
  67. GRB 210116A: AstroSat CZTI detection
  68. GRB 210120A(MASTER OT J105242.66+152355.0 / AT2021axc): Mondy optical observations
  69. GRB 210116: AstroSat LAXPC detection
  70. GRB 210120A: MASTER OT (possibly) discovery
  71. GECAM In-Flight Trigger of GRB 210120A
  72. GRB 210104A: 3.6m DOT optical upper limit
  73. Fermi GRB 210120A: Global MASTER-Net observations report
  74. GRB 210120A: BALROG localization (Fermi Trigger 632819449 / GRB 210120299)
  75. GRB 210120A: Fermi GBM Final Real-time Localization
  76. GRB 210112A: 3.6m DOT optical detection
  77. GRB 210119A (Swift J1851.2-6148): Swift-BAT refined analysis
  78. GECAM detection of a short GRB 210119A or a new SGR candidate Swift J1851.2-6148
  79. ZTF21aaeyldq: GROND observations
  80. GRB 210119A: Insight-HXMT/HE detection
  81. GRB 210119A: Fermi GBM observation
  82. ZTF21aaeyldq: LBT near-infrared observations
  83. GRB 210112A: Insight-HXMT/HE detection
  84. Short Fermi GRB 210119A or new SGR Swift J1851.2-6148: Possible MASTER Short OT detection
  85. Fermi GRB 210119A: Global MASTER-Net observations report
  86. Swift detection of a new SGR Swift J1851.2-6148 or a short GRB 210119A
  87. GRB 210119A: Fermi GBM Final Real-time Localization
  88. ZTF21aaeyldq CAHA 2.2m detection and power-law decay
  89. GRB 200613A: Host galaxy redshift from OSIRIS/GTC
  90. GRB 210112A: Deep CAHA 2.2m detection
  91. GRB 210104A: Late-time CAHA 2.2m detection
  92. Fermi trigger No 632573937: Global MASTER-Net observations report
  93. ZTF21aaeyldq: KPED observations
  94. Konus-Wind detection of GRB 210112A
  95. Correction to GCN 29288: NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS observation
  96. ZTF21aaeyldq (AT2021any): Detection of X-ray Emission with Swift/XRT
  97. ZTF21aaeyldq: 2.2m CAHA BVRI optical observations
  98. GRB 201221D: near-infrared observation with LBT
  99. ZTF21aaeyldq: NOT optical observations
  100. ZTF21aaeyldq: Lowell Discovery Telescope observations

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