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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"

7447 results found.

  1. Fermi-GBM Trigger 531686417 / 171106778 is not related to ICECUBE-171106A
  2. IceCube-171106A - IceCube observation of a high-energy neutrino candidate
  3. Fermi GBM detections of Swift J0243.6+6124 and modification of the GBM trigger configuration
  4. GRB 171010A: VLT spectroscopic identification of the associated SN 2017htp
  5. GRB 171102B: Swift detection of a burst
  6. GRB 171030A: Swift ToO observations
  7. Fermi-GBM triggers due to Swift J0243.6+6124
  8. AMI-LA observations of the new Be X-ray binary Swift J0243.6+6124
  9. Swift Trigger 783893 is probably not a GRB
  10. Retraction of high energy neutrino candidate IceCube-171028
  11. GRB 171027A: VLT optical upper limits
  12. GRB 171027A: LCO 1-m telescope observations
  13. GRB 171027A: RATIR Detection of a NIR Afterglow Candidate
  14. GRB 171027A: Swift detection of a burst
  15. Numerous Fermi-GBM Subthreshold Notices are due to Swift J0243.6+6
  16. GRB 171020A: Swift detection of a burst
  17. Search for counterpart to IceCube-171015A with ANTARES
  18. INTEGRAL SPI-ACS observation of IceCube-171015A
  19. Swift trigger 779171 is probably a noise fluctuation
  20. IceCube-171015A - IceCube observation of a high-energy neutrino candidate event
  21. GRB 171010A : Optical observations from HCT
  22. GRB 171010A: RATIR Optical and NIR Observations
  23. GRB 171013A: Swift detection of a possible burst
  24. GRB 171010B: Swift ToO observations
  25. GRB 171010A: optical observations
  26. GRB 171010A: Swift ToO observations
  27. LIGO/Virgo G298048/GW170817: updated localization from parameter estimation
  28. GRB 171007A: Swift detection of a burst
  29. GRB 171004A: Swift detection of a burst
  30. LIGO/Virgo G299232: LOFAR follow-up
  31. GRB 171003A: Swift detection of a burst or a Galactic Transient
  32. GRB 171001A: Swift detection of a burst
  33. 3.6m Devasthal Optical Telescope observations of GRB 170428A
  34. LIGO/Virgo G297595/GW170814: updated localization from parameter estimation
  35. LIGO/Virgo G298048: Summary of Pi of the Sky observations
  36. Search for counterpart to IceCube-170922A with ANTARES
  37. INTEGRAL SPI-ACS observation of AMON IceCube-170922A
  38. IceCube-170922A - IceCube observation of a high-energy neutrino candidate event
  39. GRB 170921A: Swift detection of a burst
  40. Swift trigger 773082 is probably not astrophysical
  41. LIGO/Virgo G297595: PIRATE observations
  42. LIGO/Virgo G299232: Khureltogot observations
  43. LIGO/Virgo G299232: Pierre Auger Observatory follow-up
  44. LIGO/Virgo G298389: Pierre Auger Observatory neutrino follow-up
  45. GRB 170912B: Swift detection of a burst
  46. GRB 170912A: Swift detection of a burst
  47. GRB 170906B: Swift detection of a burst
  48. GRB 170906A: Swift detection of a burst with an optical afterglow
  49. LIGO/Virgo G298389: Fermi GBM Flux Upper Limits
  50. LIGO/Virgo G299232: LOFAR follow-up
  51. Swift Triggers on MAXI J1535-571
  52. LIGO/Virgo G297595: DECam observations of BBH merger region of interest
  53. GRB 170902A: Swift detection of a burst or possible Galactic transient
  54. LIGO/Virgo G298936: PIRATE observations
  55. LIGO/Virgo G299232 ANTARES search (2)
  56. LIGO/Virgo G298048: Discovery of X-ray emission from SSS17a in NGC4993
  57. LIGO/Virgo G298048: OVRO 40m telescope follow-up
  58. LIGO/Virgo G298936: Updated localization from parameter estimation on LIGO and Virgo data
  59. LIGO/Virgo G296853: PIRATE observations
  60. LIGO/Virgo G298048: ALMA observations
  61. LIGO/Virgo G298048: Zadko Telescope 7 day observations of the OT candidate SSS17a/DLT17ck
  62. LIGO/Virgo G298936: HAWC follow-up
  63. LIGO/Virgo G299232 TZAC/TAROT observations
  64. GROND observations of GRB170827A
  65. GRB 170827A: ePESSTO NTT afterglow candidate
  66. LIGO/Virgo G299232: Transient near NGC 1343 has a somewhat blue r-i color
  67. GRB 170827A: REM optical/NIR observations
  68. LIGO/Virgo G299232: Astrosat CZTI upper limits
  69. LIGO/VIRGO G299232: Fermi GBM Observations
  70. LIGO/Virgo G299232 : Fermi-LAT search for high-energy gamma-ray counterpart
  71. LIGO/Virgo G299232: AGILE MCAL detection of a short gamma-ray candidate
  72. LIGO/Virgo G299232: INTEGRAL search for a prompt gamma-ray counterpart
  73. LIGO/Virgo G299232: COINCIDENT IceCube neutrino observation UPDATE
  74. LIGO/Virgo G299232 ANTARES search
  75. LIGO/Virgo G297595: INTEGRAL pointed follow-up observations
  76. LIGO/Virgo G299232: FOUND COINCIDENT IceCube neutrino observation
  77. LIGO/Virgo G299232: Identification of a GW Compact Binary Coalescence Candidate
  78. LIGO/Virgo G298048: MASTER Global-Net early optical observations and the Possible KiloNova SSS17a in NGC 4993 photometry and merging rate
  79. LIGO/Virgo G298048: Pierre Auger Observatory neutrino follow-up
  80. LIGO/Virgo G298048: Subaru HSC z-band imaging of the OT candidate SSS17a
  81. LIGO/Virgo G298048: HAWC follow-up
  82. LIGO/Virgo G298048: MUSE Integral Field Observations
  83. LIGO/VIRGO G298048: AAT/AAO spectroscopic observations of the GW counterpart candidate SSS17a/DLT17ck
  84. LIGO/Virgo G298048: INTEGRAL pointed follow-up observations
  85. LIGO/Virgo G298048: Properties of NGC 4993
  86. LIGO/Virgo G298936 : Fermi-LAT search for a high-energy gamma-ray counterpart
  87. LIGO/Virgo G298048: Continued VLA monitoring at 6 GHz
  88. LIGO/VIRGO G298936: Fermi GBM Observations
  89. LIGO/Virgo G298936: Updated localization from gravitational-wave data
  90. LIGO/Virgo G298936 ANTARES search
  91. LIGO/Virgo G298936: IceCube neutrino observations
  92. LIGO/Virgo G298936: Identification of a GW Binary Black Hole Candidate
  93. GRB 170822A: AbAO optical upper limit
  94. LIGO/Virgo G298048: Global properties and star-formation rate of NGC 4993
  95. LIGO/Virgo G298048: observations of optical counterpart candidate with CHILESCOPE observatory
  96. GRB 170822A:BOOTES-5/JGT optical afterglow candidate
  97. GRB 170822A: Swift detection of a burst
  98. LIGO/Virgo G298048: ASKAP observations of SSS17a and NGC 4993 at 1.345 GHz
  99. LIGO/Virgo G298048: VLA observation at 15 GHz
  100. LIGO/Virgo G298048: observations of optical counterpart candidate with CHILESCOPE observatory

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