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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 170131A detected in Swift/BAT ground processing
  2. LIGO/Virgo G270580: Las Cumbres Observatory Follow-up Observations
  3. GRB 170130A: POLAR Observation
  4. Konus-Wind observation of GRB 170127C (short/hard GRB with extended emission)
  5. GRB 170127B: Swift-BAT refined analysis
  6. GRB 170127A: Swift-BAT refined analysis
  7. GRB 170127C: Swift-XRT observations
  8. GRB 170127C: POLAR Observation
  9. GRB 170127A: GROND Upper limits
  10. GRB 170127C: AstroSat CZTI detection
  11. GRB 170127B: Swift-XRT refined Analysis
  12. GRB 170124A: POLAR Observation
  13. GRB 170127A: Swift-XRT refined Analysis
  14. GRB 170126A, Swift-BAT refined analysis
  15. GRB 170124A: CALET Gamma-Ray Burst Monitor detection
  16. Swift Trigger 735413 is not an astrophysical event
  17. GRB 170127B: Swift/UVOT Upper Limits
  18. LIGO/Virgo G268556: FLOYDS Spectrum of iPTF17cf/PS17fr Favors an AGN Classification
  19. GRB 170127A: Swift/UVOT Upper Limits
  20. GRB 170127B: Fermi GBM observation
  21. GRB 170127B: Enhanced Swift-XRT position
  22. GRB 170127B: NOT r-band upper limits
  23. GRB 170127A: Enhanced Swift-XRT position
  24. Konus-Wind observation of GRB 170126A
  25. GRB 170127C: Tiled Swift observations
  26. GRB 170127C (Fermi/GBM trigger 507173752): AGILE analysis
  27. GRB 170127C: Fermi-LAT detection
  28. GRB 170127C: Fermi GBM detection
  29. LIGO/Virgo G270580: HAWC follow-up observations
  30. GRB 170127B: MASTER-Kislovodsk early optical observations
  31. GRB 170127B: Swift detection of a short burst
  32. GRB 170127A: Prompt enhanced Swift-XRT position
  33. GRB 170127A: Swift detection of a burst
  34. GRB 170126A: AstroSat CZTI detection
  35. LIGO/Virgo G270580: Swift/UVOT follow-up of PS17yt
  36. GRB 170126A: Swift-XRT refined Analysis
  37. GRB 170126A: Swift/UVOT Detection of a Fading Afterglow
  38. GRB 170126A: Fermi GBM observation
  39. LIGO/Virgo G270580: Fermi GBM Observations
  40. GRB 170126A: Enhanced Swift-XRT position
  41. GRB 170126A: Swift detection of a burst with an optical counterpart
  42. GRB 170115A: 15 GHz upper limits from AMI
  43. LIGO/Virgo G270580: MAXI/GSC observations
  44. LIGO/Virgo G270580: NOT observations of PS17yt
  45. LIGO/Virgo G270580: Liverpool Telescope classification of EM candidates
  46. GRB 170115B: AGILE/SuperAGILE localisation
  47. LIGO/Virgo G270580: Asiago 1.82m observations of PS17ua and PS17yt
  48. LIGO/Virgo G270580: Swift-XRT follow-up of PS17yt
  49. LIGO/Virgo G270580: GMG photometric follow-up of PS17yt
  50. LIGO/Virgo G270580: 10.4m GTC spectroscopic observations of PS17yt
  51. LIGO/Virgo G270580: No change to estimate of LIGO false alarm probability
  52. LIGO/Virgo G270580: Liverpool Telescope classification of EM candidates
  53. LIGO/Virgo G270580: Pan-STARRS coverage and 124 optical transients
  54. LIGO/Virgo G268556: ANTARES upper limits
  55. GRB 170121B: AbAO optical observations
  56. LIGO/Virgo G270580: UL50 observations
  57. GRB 170121B: MASTER early optical observations of the Swift possible XT
  58. LIGO/Virgo G270580: CALET Observations
  59. LIGO/Virgo G270580: Pan-STARRS coverage and bright, rising transient PS17yt
  60. GRB 170121B: AstroSat CZTI detection
  61. GRB 170121B: Swift-XRT and UVOT observations
  62. LIGO/Virgo G270580/GW170120 : Asiago observations
  63. GRB 170121B: LCO FTN observations
  64. LIGO/Virgo G268556/GW170104: MAXI/GSC observations
  65. LIGO/Virgo G270580: A third optical transient from CNEOST
  66. GRB 170121B: Fermi GBM detection
  67. GRB 170121B: Swift ToO observations
  68. LIGO/Virgo G270580: ATLAS coverage and 4 optical transients
  69. GRB 170121B/Fermi trigger 506702667 MASTER-Amur OT detection
  70. GRB 170121A: POLAR Observation
  71. GRB 170120A: POLAR Observation
  72. LIGO/Virgo G270580: Fermi-LAT search for a high-energy gamma-ray counterpart
  73. LIGO/Virgo G270580: Two optical counterpart candidates from CNEOST
  74. LIGO/Virgo G270580: INTEGRAL search of temporally coincident prompt hard X-ray
  75. LIGO/Virgo G270580: Swift-XRT sources
  76. LIGO/Virgo G270580: Swift/BAT data search
  77. LIGO/Virgo G268556: Global MASTER Net 21 OTs detection
  78. LIGO/Virgo G270580: Mini-MegaTORTORA follow-up observations
  79. SUBJECT: LIGO/Virgo G270580: Pan-STARRS and ATLAS observations of the skymap
  80. LIGO/Virgo G270580: Observations of initial skymap by Project Mini-GWAC of SVOM
  81. LIGO/Virgo G270580: AGILE MCAL and Super-AGILE Observations
  82. LIGO/Virgo G270580 ANTARES search
  83. LIGO/Virgo G270580: Identification of a GW Burst Candidate
  84. LIGO/Virgo G268556: RATIR Observation of iPTF Candidates
  85. GRB 170117A: Swift/UVOT Upper Limits
  86. GRB 170115B: CALET Gamma-Ray Burst Monitor detection
  87. GRB 170117A: Swift-XRT observations
  88. GRB 170117A: Swift ToO observations
  89. Swift Trigger #733426: possible detection of a burst or transient
  90. GRB 170115A : AbAO optical upper limit
  91. GRB 170115A: Swift/UVOT Upper Limits
  92. GRB 170115B: Swift-XRT observations
  93. Konus-Wind observation of GRB 170115B
  94. IPN Triangulation of GRB 170115B
  95. GRB 170115B: AGILE detection
  96. LIGO/Virgo G268556: Swift-XRT observations of iPTF17cw
  97. GRB 170112A : AbAO optical observations
  98. GRB 170115A: Swift-BAT refined analysis
  99. GRB 170115A: Swift-XRT refined Analysis
  100. GRB 170114B: POLAR Observation

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