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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 181222B: Global MASTER Net observations of the short bright Fermi GRB error box.
  2. GRB 181222B : Fermi GBM detection
  3. Trigger 878548: Swift detection of AX 1631.9-4752
  4. Swift Trigger 878504 is not astrophysical
  5. GRB 181222A: Fermi GBM observation
  6. GRB 181222A: MAXI/GSC detection
  7. GRB 181217A: Insight-HXMT/HE detection
  8. GRB 181213A: Swift/UVOT Observations
  9. GRB 181213A: Mondy optical observations
  10. GRB 181213A: continued TSHAO optical observations
  11. GRB 181213A:Insight-HXMT/HE detection
  12. GRB 181212A:Insight-HXMT/HE detection
  13. Konus-Wind observation of GRB 181212A
  14. GRB 181213A: AbAO optical observations
  15. GRB 181213A: HMM-0.5m, NEXT-0.6m, CNEOST-1m optical observations
  16. GRB 181213A: NOT optical observations
  17. GRB 181213A: Swift-XRT refined Analysis
  18. GRB 181213A: Enhanced Swift-XRT position
  19. IPN Triangulation of GRB 181212A (long)
  20. GRB 181213A: Swift-BAT refined analysis
  21. GRB 181213A: GWAC-F60A upper limit
  22. GRB 181126A: MeerKAT radio observation
  23. GRB 181213A : TSHAO optical observations
  24. GRB181213A: Swift/UVOT Detection
  25. GRB 181213A: Swift-XRT observations
  26. GRB 181213A: BOOTES-5/JGT optical observations
  27. SWIFT GRB181213A Global MASTER-Net bright OT discovery
  28. GRB 181213A: Swift detection of a burst
  29. GRB 181212A: Fermi GBM Detection
  30. GRB 181126B: KAIT Follow-Up Observations of a Fermi Short GRB (Trigger 564897175)
  31. GRB 181201A: continued optical observations in Mondy
  32. MASTER OT J063515.49-624002.9 of Fermi trigger 565936249: optical observations in SAAO
  33. MASTER: OTs detection during Fermi alert trigger 565936249 early observations
  34. GRB 181201A: VLA detection
  35. GRB 181201A: ALMA detection of a fading mm afterglow
  36. INTEGRAL observations of the events in the GWTC-1 catalog
  37. GRB 181203A: GROND detection of the afterglow
  38. GRB 181126B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 564897175)
  39. GRB 181201A: continued optical observations in TSHAO and Chilesope
  40. GRB 181203A: BOOTES-3/YA optical observations
  41. GRB 181205A: a long GRB detected by INTEGRAL
  42. GRB 180112B: AstroSat CZTI detection
  43. GRB181201A: Optical afterglow measurements by GROWTH-India
  44. Swift Trigger 874754 is likely not an astrophysical event
  45. Fermi-GBM Observations During Four New GW-Detected BBH Mergers (Correction)
  46. GRB 181201A: continued optical observations in TSHAO
  47. Fermi-GBM Observations During Four New GW-Detected BBH Mergers
  48. GRB 181203A: Swift/UVOT Upper Limits
  49. GRB 181201A: Continued GROND observations show that afterglow is still bright
  50. GRB181201A: GOTO optical observations
  51. GRB 181203A: Swift-XRT refined Analysis
  52. GRB 181201A: AstroSat CZTI detection
  53. GRB 181203A: Swift-BAT refined analysis
  54. GRB 181201A: Swift/UVOT Detection
  55. GRB 181202A: Swift/UVOT Detection
  56. GRB 181201A: continued optical observations in SAAO and Chilesope
  57. GRB 181202A: RATIR Optical and NIR Observations
  58. Konus-Wind observation of GRB 181201A
  59. GRB 181203A: Enhanced Swift-XRT position
  60. GRB 181203A: Swift detection of a burst
  61. GRB 181201A: Further COATLI Optical Monitoring
  62. GRB 181201A: Insight-HXMT/HE detection
  63. GRB 181202A: Global MASTER-Net optical observations
  64. GRB 181202A: Swift-BAT refined analysis
  65. GRB 181201A: VLT/FORS2 tentative spectroscopic redshift
  66. GRB 181202A: Swift-XRT refined Analysis
  67. GRB 181201A: GROND detection of the afterglow and redshift upper limit of z < 3
  68. GRB 181201A: optical observations in Chilescope observatory
  69. GRB 181201A: Global MASTER-Net prompt optical descovery and afterglow observations
  70. GRB 181202A: Enhanced Swift-XRT position
  71. GRB 181202A: Swift detection of a burst with an optical counterpart
  72. GRB 181201A: COATLI Optical Detection
  73. GRB 181201A: Fermi-LAT detection
  74. GRB 181201A: Zeiss-1000/CrAO optical observations
  75. GRB 181201A: NOT optical observations
  76. GRB 181201A: optical observations in SAAO
  77. GRB 181201A MASTER-Net OT continued observation
  78. GRB 181201A: iTelescope optical afterglow detection
  79. GRB 181201A: Swift-XRT afterglow detection
  80. GRB 181201A: Swift ToO observations
  81. GRB 181201A: Swift-XRT afterglow
  82. GRB 181201A: likely Swift/XRT afterglow
  83. GRB 181201A MASTER-Net OT detection
  84. GRB 181201A: a long GRB detected by INTEGRAL
  85. GRB 181119A: CALET Gamma-Ray Burst Monitor detection
  86. GRB 181123B: ATCA 5/9 GHz rapid-response radio observation
  87. Short-duration GRB 181121.4: MASTER-Tavrida possible OT detection near the PGC galaxy during large Fermi error box inspection
  88. GRB 181127A : a long GRB detected by INTEGRAL
  89. GRB 181126A: Swift-BAT refined analysis
  90. GRB 181126A: No Ks-band afterglow detection with Keck I
  91. GRB 181123B: Keck further near-infrared imaging
  92. GRB 181126A: Swift/UVOT Upper Limits
  93. GRB 181126A: Swift-XRT refined Analysis
  94. GRB 181126A deep Gemini imaging
  95. GRB 181126A: Fermi GBM observation
  96. Konus-Wind observation of GRB 181121A
  97. GRB 181126A: Enhanced Swift-XRT position
  98. GRB 181126A: Prompt enhanced Swift-XRT position
  99. GRB 181126A: Swift detection of a burst
  100. GRB 181123B: Insight-HXMT/HE detection

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