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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. LIGO/Virgo G298048: VLA Detection
  2. LIGO/Virgo G298048: VISTA/VIRCAM detection of candidate counterpart
  3. LIGO/Virgo G298048: Galaxy-Targeted Optical Followup With Las Cumbres Observatory
  4. LIGO/Virgo G298048: Optical Candidate Shows No Evidence for Previous Activity in Archival SkyMapper Transient Survey Data
  5. LIGO/VIRGO G298048: The Potential Optical Counterpart in NGC 4993 Has Afterglow-Like Colors
  6. GRB 170817B: Fermi GBM detection
  7. LIGO/Virgo G298048: DLT40 follow-up observation
  8. LIGO/Virgo G298048: Las Cumbres Observatory Detection of The Possible Optical Counterpart in NGC 4993
  9. LIGO/Virgo G298048: ATCA observations of candidate host galaxies
  10. LIGO/Virgo G298048: Inspection of archival HST data at the position of the potential optical counterpart
  11. LIGO/Virgo G298048: Nearby Galaxies in the Localization Volume using the updated sky map computed using LALInference
  12. LIGO/Virgo G298048 : Fermi-LAT search for a high-energy gamma-ray counterpart
  13. LIGO/Virgo G298048: Optical Candidate Shows No Evidence for Previous Activity in Archival ASAS-SN Data
  14. LIGO/Virgo G298048: REM optical/NIR observations of candidate in NGC 4993
  15. LIGO/Virgo G298048: DLT40 optical candidate
  16. LIGO/Virgo G298048: DECam optical candidate
  17. LIGO/Virgo G298048: Potential optical counterpart discovered by Swope telescope
  18. LIGO/Virgo G298048 - Update on Fermi/GBM GRB 170817A Analysis
  19. LIGO/Virgo G298048: Updated sky map from gravitational-wave data
  20. LIGO/Virgo G298048: AGILE GRID observations
  21. LIGO/Virgo G298048: AGILE MCAL observations
  22. LIGO/Virgo G298048: Swift/BAT data search
  23. LIGO/Virgo G297595: Pierre Auger Observatory neutrino follow-up
  24. LIGO/Virgo G298048 ANTARES search
  25. LIGO/Virgo G298048: Nearby Galaxies in the Localization Volume with Face-on Assumption
  26. GRB 170817A: Fermi GBM detection
  27. LIGO/Virgo G298048: Nearby Galaxies in the Localization Volume
  28. LIGO/Virgo G298048: Insight-HXMT observations
  29. IPN Triangulation of GRB 170816A (short/hard)
  30. LIGO/Virgo G298048: Potential host galaxies from the GLADE catalog
  31. LIGO/Virgo G298048: IPN triangulation of Fermi/GBM trigger 524666471/170817529
  32. LIGO/Virgo G298048: Astrosat CZTI upper limits
  33. LIGO/Virgo G298048: Further analysis of a binary neutron star candidate with updated sky localization
  34. LIGO/Virgo G297595: Liverpool Telescope observations of MASTER transients
  35. LIGO/Virgo G298048: COINCIDENT IceCube neutrino candidate with Fermi GBM trigger 524666471/170817529
  36. LIGO/Virgo G298048: correction to the luminosity distance reported in GCN 21509
  37. LIGO/Virgo G298048: Identification of a binary neutron star candidate coincident with Fermi GBM trigger 524666471/170817529
  38. LIGO/Virgo G298048: FOUND COINCIDENT IceCube neutrino observation
  39. LIGO/Virgo G298048: INTEGRAL detection of a prompt gamma-ray counterpart
  40. LIGO/Virgo G298048: Fermi GBM trigger 170817.529 and LIGO single IFO trigger
  41. LIGO/Virgo G298048: Fermi GBM trigger 524666471/170817529: LIGO/Virgo Identification of a possible gravitational-wave counterpart
  42. GRB 170816A: Fermi GBM detection
  43. LIGO/Virgo G297595: Swift-XRT sources
  44. GRB 170805A: AstroSat CZTI detection
  45. LIGO/Virgo G296853 TZAC TAROT observations
  46. LIGO/Virgo G297595: Konus-Wind observations
  47. LIGO/Virgo G297595: MASTER MASTER Bright PSN detection in error-box
  48. LIGO/Virgo G297595: INAF VST-ESO PARANAL observations
  49. LIGO/Virgo G297595: Subaru Hyper Suprime-Cam follow-up observations
  50. LIGO/Virgo G296853: Pierre Auger Observatory neutrino follow-up
  51. LIGO/Virgo G297595: REM optical/NIR observations
  52. LIGO/Virgo G297595 : MAXI/GSC observations
  53. LIGO/Virgo G297595: Updated localization from LIGO and Virgo data
  54. GRB 170810A: VLA Detection
  55. GRB 170813A: Fermi GBM observation
  56. Fermi GBM trigger 524493492/170815526 is not a GRB
  57. LIGO/Virgo G297595: Correction to luminosity distance stated in GCN 21474
  58. LIGO/Virgo G297595: Pan-STARRS coverage and transients over the first 5hrs
  59. LIGO/Virgo G297595: Insight-HXMT observations
  60. LIGO/Virgo G297595: Nearby Galaxies in the Localization Volume
  61. LIGO/Virgo G297595: Fermi GBM Observations
  62. LIGO/Virgo G297595: Swift/BAT data search
  63. LIGO/Virgo G297595: AGILE GRID observations
  64. LIGO/Virgo G297595 : Fermi-LAT search for high-energy gamma-ray counterpart
  65. GRB 170813A: Swift/UVOT Upper Limits
  66. LIGO/Virgo G297595 ANTARES search
  67. LIGO/Virgo G297595: INTEGRAL search for a prompt gamma-ray counterpart
  68. LIGO/Virgo G297595: AGILE MCAL observations
  69. LIGO/Virgo G297595: SPI-ACS/INTEGRAL data investigations
  70. LIGO/Virgo G297595: IceCube neutrino observations
  71. LIGO/Virgo G297595: Identification of a GW Binary Merger Candidate
  72. GRB 170813A: Swift-BAT refined analysis
  73. GRB 170813A: RATIR Optical and NIR Observations
  74. GRB 170810A: AbAO optical upper limit
  75. GRB 170813A: Swift-XRT refined Analysis
  76. GRB 170813A: Enhanced Swift-XRT position
  77. GRB 170813A: Swift detection of a burst
  78. LIGO/Virgo G296853: Liverpool Telescope classification of MASTER OT J013646.48-140323.5
  79. GRB 170728B: 15 GHz upper limits from AMI
  80. GRB 170728A: 15 GHz upper limits from AMI
  81. GRB 170714A: 15 GHz upper limits from AMI
  82. GRB 170711A: 15 GHz upper limits from AMI
  83. GRB 170710C: 15 GHz upper limits from AMI
  84. GRB 170710B: 15 GHz upper limits from AMI
  85. GRB 170626A: 15 GHz upper limits from AMI
  86. LIGO/Virgo G296853: BOOTES-1 and GTC optical observations
  87. GRB 170810A: Swift-BAT refined analysis
  88. LIGO/Virgo G296853: Insight-HXMT observations
  89. LIGO/Virgo G296853 : MAXI/GSC observations
  90. GRB 170810A: Swift-XRT refined Analysis
  91. GRB 170810A: Swift/UVOT Detection
  92. GRB 170810A: Fermi GBM observation
  93. GRB 170810A: Fermi-LAT detection
  94. GRB 170810A: Enhanced Swift-XRT position
  95. GRB 170810A: Swift detection of a burst with a bright optical counterpart
  96. GRB 170810A: MASTER-NET very bright OT detection
  97. LIGO/Virgo G296853: HAWC follow-up
  98. Konus-Wind observation of GRB 170808B
  99. LIGO/Virgo G296853: Super-AGILE observations
  100. LIGO/Virgo G296853: MASTER SN detection near center error-area

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