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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 160104A: MITSuME Okayama Ks-band upper-limit
  2. GRB 160104B: MAXI/GSC detection
  3. GRB 160104A: MITSuME Akeno Optical Observation
  4. GRB 160104A: LCOGT-FTN afterglow candidate
  5. GRB 160104A: Swift detection of a burst
  6. GRB 160101A: CALET Gamma-Ray Burst Monitor detection
  7. LIGO/Virgo G211117: Fermi/LAT observations
  8. LIGO/Virgo G211117: Liverpool Telescope classification of EM candidates
  9. LIGO/Virgo G211117: Gemini classification of 7 Pan-STARRS transients
  10. GRB 151231A: CALET Gamma-Ray Burst Monitor detection
  11. LIGO/Virgo G211117: LOFAR follow-up
  12. GRB 160102A: Swift-XRT observations
  13. LIGO/Virgo G211117: Liverpool Telescope classification of EM candidates
  14. LIGO/Virgo G211117: PESSTO classification of Pan-STARRS transients
  15. GRB 160101A: MITSuME Akeno optical upper limits
  16. LIGO/Virgo G211117: MASTER OTs 26.XII.2015 - 01.I.2016
  17. LIGO/Virgo G211117: CSS/CRTS observations on 29/30 Dec 2015 UT
  18. GRB 160102A: Tiled Swift observations
  19. GRB 160102A: MAXI/GSC detection
  20. LIGO/Virgo G211117: La Silla - QUEST observations 2015 Dec 28 - 30
  21. GRB 160101B: Fermi-LAT detection
  22. GRB 160101B: Fermi GBM detection
  23. GRB 160101A: Swift/UVOT Detection
  24. GRB 160101A: Fermi GBM observation
  25. GRB 160101A: Swift-XRT afterglow detection
  26. GRB 160101A: Tiled Swift observations
  27. GRB 160101A: MAXI/GSC detection
  28. GRB 151227B: CALET Gamma-Ray Burst Monitor detection
  29. LIGO/Virgo G211117: Liverpool Telescope classification of EM candidates
  30. LIGO/Virgo G211117: FLOYDS Classification of SMTJ13331687-1607330 as a Two-Week-Old Type Ia Supernova
  31. LIGO/Virgo G211117: LBT follow-up imaging of iPTF15fhq
  32. GRB 151231B: Fermi GBM observation
  33. GRB 151231A: Fermi GBM observation
  34. LIGO/Virgo G211117: 44 transients from Pan-STARRS data during 2015-12-28/30
  35. Trigger 668949: Swift detection of V 404 Cyg
  36. LIGO/Virgo G211117: MAXI/GSC observations
  37. MASTER-NET observations of V404Cyg Swift Trigger 668877
  38. LIGO/Virgo G211117: Liverpool Telescope followup of EM candidates
  39. Konus-Wind observation of GRB 151227B
  40. LIGO/Virgo G211117: VLA follow-up
  41. LIGO/Virgo G211117: LBT Follow-up of iPTF15fen
  42. Trigger 668879: Swift detection of V 404 Cyg again
  43. Trigger 668877: Swift detection of V 404 Cyg
  44. LIGO/Virgo G211117: MAGIC very-high energy gamma-ray observations
  45. LIGO/Virgo G211117: INAF TNG follow-up of MASTER OT J020906.21+013800.1
  46. LIGO/Virgo G211117: OAO-WFC NIR follow-up observations
  47. IPN Triangulation of GRB 151227B
  48. GRB 151228A: Correction to GCN 18770
  49. LIGO/Virgo G211117: SkyMapper observations and transient candidate
  50. GRB 151228A: Swift-XRT refined Analysis
  51. V404Cyg Swift Trigger 668097: CrAO RT-22 radio observations
  52. LIGO/Virgo G211117: MASTER Observations of the 3 iPTF candidates
  53. V404Cyg Swift Trigger 668097: AbAO optical observations
  54. GRB 151228B: Swift/UVOT Detection
  55. GRB 151229A: MITSuME Akeno optical upper limits
  56. LIGO/Virgo G211117: Optical Observations with Kiso Schmidt telescope and KWFC
  57. LIGO/Virgo G211117: List of near-term future observation regions by Project Mini-GWAC of SVOM
  58. LIGO/Virgo G211117: iPTF Optical Transient Candidates
  59. GRB 151229A: MITSuME Okayama upper limits
  60. GRB 151229A Swift-BAT Spectral lag analysis
  61. LIGO/Virgo G211117: La Silla - QUEST observations 2015 Dec 28, 29
  62. GRB 151228B: MITSuME Akeno optical upper limits
  63. GRB 151229A: Swift-XRT refined Analysis
  64. GRB 151229A: Fermi GBM observation
  65. GRB 151228B: Fermi GBM observation
  66. GRB 151228A: Swift-BAT refined analysis
  67. GRB 151229A: Swift/UVOT observations
  68. GRB 151228B: Swift-BAT refined analysis
  69. GRB 151229A: Swift-BAT refined analysis
  70. GRB 151229A: Enhanced Swift-XRT position
  71. GRB 151228B: Swift-XRT refined Analysis
  72. LIGO/Virgo G211117: Further Swift-XRT sources
  73. GRB 151228A: MITSuME Akeno optical upper limits
  74. GRB 151228A: T60 observations
  75. GRB 151229A: Swift detection of a short burst
  76. LIGO/Virgo G211117: DESGW program observations with DECam
  77. GRB 151228B: Enhanced Swift-XRT position
  78. LIGO/Virgo G211117: Optical NIR observation with Kanata telescope
  79. LIGO/Virgo G211117: Fermi GBM Observations
  80. LIGO/Virgo G211117: Optical follow-up with Kanata telescope
  81. GRB 151228B: Swift detection of a burst with an optical detection
  82. LIGO/Virgo G211117: MASTER Observations and Inspection + OT
  83. LIGO/Virgo G211117: INTEGRAL was inactive at the time of the event
  84. GRB 151228A: Fermi GBM observation
  85. LIGO/Virgo G211117: Pan-STARRS1 observations 2015-12-28
  86. LIGO/Virgo G211117: INAF VST-ESO PARANAL observations
  87. LIGO/Virgo G211117: Further Swift-XRT sources
  88. LIGO/Virgo G211117: Swift-XRT sources
  89. GRB 151228A: Swift detection of a short burst
  90. LIGO/Virgo G211117: SWASP optical observations
  91. LIGO/Virgo G211117: MASTER possible OT detection at the begining of inspection
  92. LIGO/Virgo G211117: Identification of a GW CBC Candidate
  93. GRB 151227B: Fermi GBM detection
  94. GRB 151227A: Fermi GBM detection
  95. GRB 151212A iTelescope observation
  96. GRB 151225A: CALET Gamma-Ray Burst Monitor detection of a possible short GRB
  97. Konus-Wind observation of GRB 151222A
  98. Fermi GBM trigger 472694170/151224997 is not a GRB
  99. V404Cyg Swift Trigger 668097: TSHAO optical observations
  100. IPN Triangulation of GRB 151222A (short/hard)

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