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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. GRB 210205A: Enhanced Swift-XRT position
  2. GRB 210205A： GWAC-F60A optical upper limit
  3. GRB 210205A: Swift detection of a burst
  4. Fermi GRB 210204B: Global MASTER-Net observations report
  5. Fermi GRB 210204A: Global MASTER-Net observations report
  6. GRB 210204B: Fermi GBM Final Real-time Localization
  7. GRB 210204: Fermi GBM observation
  8. GRB 210204A: GECAM detection
  9. GRB 210204A: BALROG localization (Fermi Trigger 634112970 / GRB 210204270)
  10. GRB 210204A: Fermi GBM Final Real-time Localization
  11. GRB 210202A: AGILE/MCAL detection
  12. Fermi GBM Observations of a bright burst from SGR J1935+2154
  13. GRB 210202A: Fermi GBM detection
  14. GRB 210202A: Fermi-LAT detection
  15. Fermi GRB 210202A: Global MASTER-Net observations report
  16. Fermi trigger No 633963272: Global MASTER-Net observations report
  17. Recent activity of SGR 1935+2154 as observed by CGBM
  18. GRB 210202A: BALROG localization (Fermi Trigger / GRB 210202841)
  19. INTEGRAL detection of a short burst from SGR 1935+2154
  20. GRB 210202A: Fermi GBM Final Real-time Localization
  21. GRB 210131A: GECAM detection
  22. Fermi trigger No 633879387: Global MASTER-Net observations report
  23. GECAM observations of SGR 1935+2154
  24. GRB 210129A: Insight-HXMT/HE detection
  25. Continued Chandra observations of GW170817 at ~3.3 years since merger
  26. Fermi GBM Observations of SGR J1935+2154
  27. Konus-Wind detection of two bright bursts from SGR 1935+2154
  28. GRB 140330A: Swift-XRT refined Analysis
  29. GRB 140320B: Swift-XRT refined Analysis
  30. GRB 140402A: Swift-XRT refined Analysis
  31. GRB 140104B: Swift-XRT refined Analysis
  32. GRB 210126A: AstroSat CZTI detection
  33. GRB 210124B: AstroSat CZTI detection
  34. GRB 210123A: AstroSat CZTI detection
  35. IPN triangulation of a bright burst from SGR 1935+2154
  36. ZTF21aaeyldq: Observations with the 3.6m DOT
  37. GECAM detection of a short burst probably from SGR 1935+2154
  38. GRB 210127A: Fermi GBM Final Real-time Localization
  39. GRB 210120A: Fermi GBM detection
  40. Fermi trigger No 633348010: Global MASTER-Net observations report
  41. HAWC Transient event on 2021/01/25
  42. Konus-Wind detection of GRB 210121A
  43. Konus-Wind detection of GRB 210124B
  44. GRB 210126A: GECAM detection
  45. IPN triangulation of GRB 210124B (short)
  46. GRB 210126A: BALROG localization (Fermi Trigger / GRB 210126417)
  47. GRB 210124B: Insight-HXMT/HE detection
  48. Fermi trigger No 633257525: Global MASTER-Net observations report
  49. GRB 210123A: Fermi GBM Final Localization
  50. GECAM detection of a burst possibly from the X-ray burster 4U 0614+09 or GRB 210124A
  51. GRB 210123A: Insight-HXMT/HE detection
  52. IPN triangulation of GRB 210121A
  53. GRB 210121A: GECAM detection
  54. GRB 210121A: Insight-HXMT/HE detection
  55. GRB 210120A : 1.3m DFOT optical observations
  56. ZTF21aaeyldq: GROND and CAHA jet break confirmation
  57. ZTF20aaeyldq: VLA radio detection
  58. GRB 210116A: AstroSat CZTI detection
  59. GRB 210120A(MASTER OT J105242.66+152355.0 / AT2021axc): Mondy optical observations
  60. GRB 210116: AstroSat LAXPC detection
  61. GRB 210120A: MASTER OT (possibly) discovery
  62. GECAM In-Flight Trigger of GRB 210120A
  63. GRB 210104A: 3.6m DOT optical upper limit
  64. Fermi GRB 210120A: Global MASTER-Net observations report
  65. GRB 210120A: BALROG localization (Fermi Trigger 632819449 / GRB 210120299)
  66. GRB 210120A: Fermi GBM Final Real-time Localization
  67. GRB 210112A: 3.6m DOT optical detection
  68. GRB 210119A (Swift J1851.2-6148): Swift-BAT refined analysis
  69. GECAM detection of a short GRB 210119A or a new SGR candidate Swift J1851.2-6148
  70. ZTF21aaeyldq: GROND observations
  71. GRB 210119A: Insight-HXMT/HE detection
  72. GRB 210119A: Fermi GBM observation
  73. ZTF21aaeyldq: LBT near-infrared observations
  74. GRB 210112A: Insight-HXMT/HE detection
  75. Short Fermi GRB 210119A or new SGR Swift J1851.2-6148: Possible MASTER Short OT detection
  76. Fermi GRB 210119A: Global MASTER-Net observations report
  77. Swift detection of a new SGR Swift J1851.2-6148 or a short GRB 210119A
  78. GRB 210119A: Fermi GBM Final Real-time Localization
  79. ZTF21aaeyldq CAHA 2.2m detection and power-law decay
  80. GRB 200613A: Host galaxy redshift from OSIRIS/GTC
  81. GRB 210112A: Deep CAHA 2.2m detection
  82. GRB 210104A: Late-time CAHA 2.2m detection
  83. Fermi trigger No 632573937: Global MASTER-Net observations report
  84. ZTF21aaeyldq: KPED observations
  85. Konus-Wind detection of GRB 210112A
  86. Correction to GCN 29288: NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS observation
  87. ZTF21aaeyldq (AT2021any): Detection of X-ray Emission with Swift/XRT
  88. ZTF21aaeyldq: 2.2m CAHA BVRI optical observations
  89. GRB 201221D: near-infrared observation with LBT
  90. ZTF21aaeyldq: NOT optical observations
  91. ZTF21aaeyldq: Lowell Discovery Telescope observations
  92. ZTF21aaeyldq: observations with the 3.6m Devasthal Optical Telescope
  93. ZTF21aaeyldq: GTC Redshift and GRB afterglow nature confirmation
  94. GRB 201015A: evidence of supernova in LBT spectra
  95. ZTF Discovery of ZTF21aaeyldq (AT2021any): a Hostless, Young, and Rapidly Fading Transient
  96. GRB 210104A: JCMT SCUBA-2 sub-mm observations
  97. GRB 210112A: Swift/UVOT Detection
  98. GRB 210112A: Mondy optical observations
  99. GRB 210112A: 1.3m DFOT Optical upper limit
  100. GRB 210112A: OSN second epoch, decay

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