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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 160113A: Fermi GBM detection
  2. GRB 160113A: Swift ToO observations
  3. GRB 160113A: iPTF P48 Observations and Optical Transient Candidates
  4. LIGO/Virgo G184098: Refined localizations from CBC parameter estimation
  5. Konus-Wind observation of GRB 160107A
  6. GRB 160104A: Swift/UVOT Detection
  7. IPN Triangulation of GRB 151231A
  8. Konus-Wind observation of GRB 151229B
  9. LIGO/Virgo G211117: Updated FAR estimate based on offline re-analysis
  10. IPN Triangulation of GRB 151229B (extremely intense/long)
  11. LIGO/Virgo G184098: Updated FAR estimate
  12. LIGO/Virgo G211117: Distance estimate from GW data compared to redshift of PS15dpn
  13. LIGO/Virgo G211117: Swift observations of PS15dpn
  14. LIGO/Virgo G211117: iPTF Observations of PS15dpn
  15. LIGO/Virgo G211117: PESSTO classification of MASTER J165420.77-615258
  16. LIGO/Virgo G211117: VLA follow-up
  17. GRB 160107A: CALET Gamma-Ray Burst Monitor detection
  18. GRB 160107A: Fermi GBM observation
  19. LIGO/Virgo G211117: Pi of the Sky observations
  20. LIGO/Virgo G211117: VISTA imaging
  21. GRB 160104A: Continued MITSuME Akeno Optical Observation
  22. LIGO/Virgo G211117: Subaru Hyper Suprime-Cam follow-up observation
  23. GRB 160107A: MAXI/GSC detection
  24. Konus-Wind observation of GRB 160101A
  25. Konus-Wind observation of GRB 151225A
  26. IPN Triangulation of GRB 151225A (short/hard)
  27. LIGO/Virgo G211117: MASTER OT in ESO138-006 galaxy
  28. LIGO/Virgo G211117: Further Swift-XRT sources
  29. GRB 160104A: Nishi-Harima MINT Observations
  30. LIGO/Virgo G211117: Liverpool Telescope classification of EM candidates
  31. GRB 160104A: Spectroscopic observations from 10.4m GTC
  32. GRB 160104A: Swift-XRT refined Analysis
  33. GRB 160104A: Swift-BAT refined analysis
  34. GRB 160104A: Fermi GBM observation
  35. GRB 160104A: Mini-GWAC upper limit during prompt emission phase
  36. GRB 160104A: GWAC upper limit during prompt emission phase
  37. GRB 160104A: MITSuME Okayama upper limits
  38. LIGO/Virgo G211117: Summary of Pan-STARRS transients
  39. GRB 160104A: Xinglong TNT optical observation
  40. LIGO/Virgo G211117: INAF TNG follow-up of Kanata telescope candidate
  41. GRB 160104A: Enhanced Swift-XRT position
  42. GRB 160104A: MASTER early OT detection
  43. GRB 160104A: MITSuME Okayama Ks-band upper-limit
  44. GRB 160104B: MAXI/GSC detection
  45. GRB 160104A: MITSuME Akeno Optical Observation
  46. GRB 160104A: LCOGT-FTN afterglow candidate
  47. GRB 160104A: Swift detection of a burst
  48. GRB 160101A: CALET Gamma-Ray Burst Monitor detection
  49. LIGO/Virgo G211117: Fermi/LAT observations
  50. LIGO/Virgo G211117: Liverpool Telescope classification of EM candidates
  51. LIGO/Virgo G211117: Gemini classification of 7 Pan-STARRS transients
  52. GRB 151231A: CALET Gamma-Ray Burst Monitor detection
  53. LIGO/Virgo G211117: LOFAR follow-up
  54. GRB 160102A: Swift-XRT observations
  55. LIGO/Virgo G211117: Liverpool Telescope classification of EM candidates
  56. LIGO/Virgo G211117: PESSTO classification of Pan-STARRS transients
  57. GRB 160101A: MITSuME Akeno optical upper limits
  58. LIGO/Virgo G211117: MASTER OTs 26.XII.2015 - 01.I.2016
  59. LIGO/Virgo G211117: CSS/CRTS observations on 29/30 Dec 2015 UT
  60. GRB 160102A: Tiled Swift observations
  61. GRB 160102A: MAXI/GSC detection
  62. LIGO/Virgo G211117: La Silla - QUEST observations 2015 Dec 28 - 30
  63. GRB 160101B: Fermi-LAT detection
  64. GRB 160101B: Fermi GBM detection
  65. GRB 160101A: Swift/UVOT Detection
  66. GRB 160101A: Fermi GBM observation
  67. GRB 160101A: Swift-XRT afterglow detection
  68. GRB 160101A: Tiled Swift observations
  69. GRB 160101A: MAXI/GSC detection
  70. GRB 151227B: CALET Gamma-Ray Burst Monitor detection
  71. LIGO/Virgo G211117: Liverpool Telescope classification of EM candidates
  72. LIGO/Virgo G211117: FLOYDS Classification of SMTJ13331687-1607330 as a Two-Week-Old Type Ia Supernova
  73. LIGO/Virgo G211117: LBT follow-up imaging of iPTF15fhq
  74. GRB 151231B: Fermi GBM observation
  75. GRB 151231A: Fermi GBM observation
  76. LIGO/Virgo G211117: 44 transients from Pan-STARRS data during 2015-12-28/30
  77. Trigger 668949: Swift detection of V 404 Cyg
  78. LIGO/Virgo G211117: MAXI/GSC observations
  79. MASTER-NET observations of V404Cyg Swift Trigger 668877
  80. LIGO/Virgo G211117: Liverpool Telescope followup of EM candidates
  81. Konus-Wind observation of GRB 151227B
  82. LIGO/Virgo G211117: VLA follow-up
  83. LIGO/Virgo G211117: LBT Follow-up of iPTF15fen
  84. Trigger 668879: Swift detection of V 404 Cyg again
  85. Trigger 668877: Swift detection of V 404 Cyg
  86. LIGO/Virgo G211117: MAGIC very-high energy gamma-ray observations
  87. LIGO/Virgo G211117: INAF TNG follow-up of MASTER OT J020906.21+013800.1
  88. LIGO/Virgo G211117: OAO-WFC NIR follow-up observations
  89. IPN Triangulation of GRB 151227B
  90. GRB 151228A: Correction to GCN 18770
  91. LIGO/Virgo G211117: SkyMapper observations and transient candidate
  92. GRB 151228A: Swift-XRT refined Analysis
  93. V404Cyg Swift Trigger 668097: CrAO RT-22 radio observations
  94. LIGO/Virgo G211117: MASTER Observations of the 3 iPTF candidates
  95. V404Cyg Swift Trigger 668097: AbAO optical observations
  96. GRB 151228B: Swift/UVOT Detection
  97. GRB 151229A: MITSuME Akeno optical upper limits
  98. LIGO/Virgo G211117: Optical Observations with Kiso Schmidt telescope and KWFC
  99. LIGO/Virgo G211117: List of near-term future observation regions by Project Mini-GWAC of SVOM
  100. LIGO/Virgo G211117: iPTF Optical Transient Candidates

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