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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 160321A: Swift detection of a probable burst
  2. GRB 160310A: Terskol 2-m observations
  3. IPN Triangulation of GRB 160310A
  4. LIGO/Virgo G211117: EWE for NOWT follow-up of northern sky
  5. SGR 0755-2933, Swift-BAT refined analysis
  6. GRB 160131A: 15 GHz upper limits from AMI-LA
  7. GRB 160310A: A further Swift-XRT observation, no afterglow detected
  8. Swift detection of a likely new SGR: SGR 0755-2933
  9. GRB 160314A: Continued RATIR Optical and NIR Observations
  10. GRB 160313A: Mondy optical upper limit
  11. GRB 160314A: GROND optical/NIR observations
  12. GRB 160314A: ISON-Ussuriysk optical upper limit, updated photometry and correction of GCN 19184
  13. GRB 160314B: Fermi GBM observation
  14. GRB 160314B: Fermi-LAT detection
  15. GRB 160314A: RATIR Optical and NIR Observations
  16. GRB 160314A: Mondy optical observations
  17. GRB 160313A: Swift/UVOT Upper Limits
  18. LIGO/Virgo G194575: EWE for NOWT follow-up of northern sky
  19. GRB 160314A: VLT/X-shooter redshift
  20. GRB 160314A: NOT afterglow observations
  21. GRB 160314A: Swift-XRT refined Analysis
  22. GRB 160314A: Optical observations from OSN
  23. GRB 160314A: Swift-BAT refined analysis
  24. GRB 160314A: Swift/UVOT Detection
  25. GRB 160228A: GROND afterglow confirmation and X-shooter host candidate redshift
  26. GRB 160314A: Enhanced Swift-XRT position
  27. GRB 160314A: ISON-Ussuriysk optical upper limit
  28. GRB 160314A: Weihai optical upper limit
  29. GRB 160314A: Swift detection of a burst
  30. GRB 160313A, Swift-BAT refined analysis
  31. Fermi GBM trigger 479509107/160312874 is not a GRB
  32. GRB 160313A: Chante-Perdrix Observatory optical observations
  33. GRB 160313A: MASTER-Net optical observations
  34. GRB 160313A: LT observations
  35. GRB 160313A: Swift-XRT refined Analysis
  36. GRB 160313A: TAROT Calern observatory optical observations
  37. GRB 160313A: Enhanced Swift-XRT position
  38. GRB 160313A: RATIR Optical and NIR Observations
  39. GRB 160313A: SAO RAS observations
  40. GRB 160313A: Swift detection of a burst
  41. GRB 160310A: MASTER-Kislovods observations
  42. GRB 160310A: Further NOT observations
  43. GRB 160310A: Swift/UVOT Upper Limits
  44. Konus-Wind observation of GRB 160310A (possible ultra-long GRB?)
  45. GRB 160310A: RATIR Optical and NIR Observations
  46. GRB 160307A: CALET Gamma-Ray Burst Monitor detection of a possible short GRB
  47. GRB 160310A: NOT optical observations
  48. GRB 160310A: LCOGT-SAAO optical upper limits
  49. GRB 160310A: Swift-XRT observations
  50. GRB 160310A: Fermi GBM observation
  51. GRB 160303A: GTC imaging of possible host galaxy
  52. GRB 160310A: Swift ToO observations
  53. GRB 160310A: Fermi-LAT detection
  54. Swift Trigger 678197 is a noise fluctuation
  55. LIGO/Virgo G211117: HAWC follow-up of northern sky
  56. Trigger 677981: Swift detection of IGRJ17091-3624
  57. GRB 160303A: X-shooter spectroscopy
  58. Swift trigger 677890 is noise
  59. GRB 160303A: Continued optical monitoring from NOT
  60. GRB 160303A: JCMT SCUBA-2 sub-mm observation
  61. GRB160303A: further GROND observations
  62. GRB 160303A: 9.8 GHz VLA upper limit
  63. GRB 160303A, Swift-BAT refined analysis
  64. GRB 160303A: MMT Optical Detection
  65. GRB 160303A: Continued RATIR Optical and NIR Observations
  66. LIGO/Virgo G211117: GRAWITA LBT follow-up of PS15dpn
  67. GRB 160303A: GROND Optical Detection
  68. GRB 160303A: Observations from T150 OSN
  69. GRB 160303A: VLT/FORS2 afterglow obervations
  70. GRB 160303A: BOAO R-band Detection
  71. GRB 160303A: McDonald 2.1m CQUEAN Detection
  72. GRB 160303A SMA observation
  73. GRB 160303A iTelescope observation
  74. GRB 160303A: Swift-XRT refined Analysis
  75. GRB 160303A: Optical observations from the NOT
  76. Swift possibly triggered on IGR17091-3624
  77. GRB 160303A: Swift/UVOT Detection
  78. GRB 160303A: RAPTOR Observations During Gamma-Ray Emitting Interval
  79. GRB 160303A: Enhanced Swift-XRT position
  80. GRB 160303A: RATIR Optical and NIR Afterglow Detection
  81. GRB 160303A: MITSuME Akeno optical upper limits
  82. GRB 160303A: LCOGT-FTN optical observations
  83. GRB 160303A: MITSuME Okayama upper limits
  84. GRB 160303A: ISON-NM early optical early limits
  85. GRB 160303A: Swift detection of a burst, possibly short
  86. GRB 160227A: LOAO 1.0m optical detection
  87. GRB 160227A: McDonald 0.8m Detection
  88. GRB 160228A: Swift/UVOT Upper Limits
  89. GRB 160227A: Swift/UVOT Detection
  90. GRB160228A: Further analyses on spectral lag and extended emission
  91. GRB 160228A: Mondy optcial observations
  92. GRB 160228A: RATIR Optical and NIR Observations
  93. GRB 160228A: MASTER-Amur prompt observations
  94. GRB 160228A: Swift-XRT refined Analysis
  95. GRB 160227A: MASTER prompt OT Detection and LC
  96. GRB 160227A: AROMA-N Optical Observation
  97. GRB 160228A: GROND Afterglow Candidate
  98. GRB 160228A: Swift-BAT refined analysis
  99. GRB 160228A: optical observations
  100. GRB 160227B: Fermi GBM detection

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