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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 171030A: IPN error box through NSs probability merging rate map
  2. GRB 171030A: Fermi GBM detection
  3. GRB 171030A: Swift non-localization with BAT, XRT and UVOT
  4. GRB 171030A: Swift ToO observations
  5. IPN Triangulation of GRB 171030A (short)
  6. Fermi-GBM triggers due to Swift J0243.6+6124
  7. Swift Trigger 783893: KAIT Optical Observations
  8. GRB 171027A: KAIT Optical Upper Limit
  9. Swift Triggers 784159 and 784160 are not bursts
  10. GRB 171022A: Fermi-LAT detection retraction
  11. Konus-Wind observation of GRB 171027A
  12. AMI-LA observations of the new Be X-ray binary Swift J0243.6+6124
  13. Swift Trigger 783893: LCO 1-m telescope observations
  14. Swift Trigger 783893 is probably not a GRB
  15. GRB 171027A, Swift-BAT refined analysis
  16. Retraction of high energy neutrino candidate IceCube-171028
  17. GRB 171027A: Swift/UVOT Upper Limits
  18. GRB 171027A: Swift-XRT refined Analysis
  19. GRB 171027A: Enhanced Swift-XRT position
  20. GRB 171027A: RATIR Confirmation of Fading and Photo-z
  21. GRB 171027A: VLT optical upper limits
  22. GRB 171027A: LCO 1-m telescope observations
  23. GROND observations of GRB 171027A: correction
  24. GRB 171027A: RATIR Detection of a NIR Afterglow Candidate
  25. GROND observations of GRB 171027A
  26. GRB 171027A: MASTER-OAFA (Argentina) early prompt optical observations
  27. GRB 171027A: Prompt enhanced Swift-XRT position
  28. GRB 171027A: Swift detection of a burst
  29. Konus-Wind observation of GRB 171022A
  30. IPN Triangulation of GRB 171022A
  31. GRB 171013B CALET Gamma-Ray Burst Monitor detection
  32. Fermi GBM trigger 530617076/171025401 is not a GRB
  33. Swift trigger 781740: Further analysis from Swift and Fermi/GBM
  34. Numerous Fermi-GBM Subthreshold Notices are due to Swift J0243.6+6
  35. GRB 171022A: Fermi GBM detection
  36. GRB 171022A: Fermi-LAT detection
  37. Swift Trigger 781740 is not a burst
  38. Fermi GBM Observations of IceCube-171015A
  39. GRB 171020A: Continued RATIR Optical and NIR Observation
  40. GRB 171020A: TAROT Calern observatory optical observations
  41. GRB 171020A: Swift/UVOT Upper Limits
  42. GRB 171020A: NOT spectroscopic redshift
  43. GRB 171020A: Swift-BAT refined analysis
  44. GRB 171020A: RATIR Optical and NIR Observations
  45. GRB 171020A: Swift-XRT refined Analysis
  46. GRB 171020A: Enhanced Swift-XRT position
  47. GRB 171020A: LT observations
  48. GRB 171020A: Correction of alpha in GCN 22031
  49. GRB 171020A: Confirmation of OT fading
  50. GRB 171020A: Mini-MegaTORTORA upper limits on simultaneous optical emission
  51. GRB 171020A: NOT optical afterglow detection
  52. GRB 171020A: Swift detection of a burst
  53. Fermi-GBM Detection of possible burst from AXP CXOU J164710.2-455216/PSR J1647-4552
  54. GRB 171011B: Insight-HXMT detection
  55. Trigger 780207: Swift triggers again on AXP CXOU J164710.2-455216/PSR J1647-4552
  56. Swift Trigger on AXP CXOU J164710.2-455216/PSR J1647-4552
  57. GRB 171010B: Swift-XRT afterglow detection
  58. GRB 171011B CALET Gamma-Ray Burst Monitor detection
  59. Trigger 779762: Swift detection of Vela X-1
  60. Trigger 779351: Swift detection of Swift J0243.6+6124
  61. Search for counterpart to IceCube-171015A with ANTARES
  62. INTEGRAL SPI-ACS observation of IceCube-171015A
  63. Swift trigger 779171 is probably a noise fluctuation
  64. IceCube-171015A - IceCube observation of a high-energy neutrino candidate event
  65. GRB 171010A: VLA Observations
  66. GRB 171010A: VLA Detection
  67. GRB 171010A: A detection of a radio source by AMI
  68. GRB 171010A : Optical observations from HCT
  69. GRB 171010A: RATIR Optical and NIR Observations
  70. BAT trigger 778435 is not a GRB.
  71. GRB 171010B: Swift-XRT observations
  72. GRB 171013A: TAROT Calern observatory optical observations
  73. GRB 171013A: Swift detection of a possible burst
  74. GRB 171011A: Swift-BAT refined analysis
  75. Konus-Wind observation of GRB 171011B
  76. GRB 171010A: Swift/UVOT Detection
  77. Konus-Wind observation of GRB 171010A
  78. GRB 171010A: ePESSTO NTT spectroscopic redshift
  79. GRB 171010A: MITSuME Akeno Optical Observation
  80. GRB 171010A: NOT optical observations
  81. GRB 171010B: Fermi GBM detection
  82. IPN Triangulation of GRB 171011B (long/very bright)
  83. GRB 171010B: Swift ToO observations
  84. GRB 171011A: TAROT Calern observatory optical observations
  85. GRB 171010B: Swift detection of a burst
  86. GRB 171011A: MASTER-SAAO optical observations
  87. GRB 171011A: Swift detection of a burst
  88. GRB 171010A: Fermi GBM observation
  89. GRB 171010A: LCO 1m telescope observations
  90. GRB171010A: AstroSat CZTI detection
  91. GRB 171010A: Swift-XRT afterglow detection
  92. GRB 171010A: optical observations
  93. GRB 171010A: OT, spectrum, and possible host galaxy
  94. GRB 171010A: Swift ToO observations
  95. GRB 171010A: Fermi-LAT detection
  96. GRB 171007A: Swift/UVOT Upper Limits
  97. LIGO/Virgo G298048/GW170817: updated localization from parameter estimation
  98. LIGO/Virgo G298048: Mid-Infrared Spitzer/IRAC Observations at 3.6 and 4.5 microns
  99. GRB 171007A: Swift-BAT refined analysis
  100. GRB 171007A: Fermi GBM observation

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