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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"

28044 results found.

  1. GRB 150407A: Swift-XRT observations
  2. GRB 150407A: optical observations
  3. Swift triggered on a source in Terzan 5 (trigger=637212)
  4. GRB 150404A: Fermi GBM detection
  5. Fermi trigger 449861706: MASTER-SAAO possible candidate to OT of Short GRB
  6. GRB 150403A: Swift-BAT refined analysis
  7. GRB 150403A: Swift/UVOT Detection
  8. GRB 150323C: CrAO optical observations
  9. GRB 150323C: additional optical observations in Mondy
  10. GRB 150323C: Khureltogot optical observations
  11. GRB 150403A: Swift-XRT refined Analysis
  12. GRB 150403A: Fermi-LAT detection
  13. GRB 150403A: Enhanced Swift-XRT position
  14. GRB 150403A: Swift detection of a burst with an optical counterpart
  15. GRB 150402A: results of Swift observations
  16. GRB 150402A: RATIR Optical Observations
  17. IPN Triangulation of GRB 150330A (long/very intense)
  18. GRB 150330A: Fermi GBM detection
  19. GRB 150323B: Swift-XRT afterglow detection
  20. GRB 141121A: GMG observation
  21. GRB 150323C: possible host galaxy detection
  22. GRB 141212A: GMG observation limit
  23. GRB 141220A: GMG observation limit
  24. GRB 141225A: GMG observation limit
  25. GRB 150120B: GMG observation
  26. GRB 150317A: likely host galaxy detection
  27. GRB 150323B: Khureltogot optical observations
  28. GRB 150323C: Nishi-Harima NIR Observations
  29. GRB 150323A: AAO optical observations
  30. GRB 150323C: MITSuME Akeno Optical observation
  31. GRB 150220A: Optical observations at Kyiv comet station
  32. GRB 150323C; Konkoly optical observations
  33. GRB 150323B; Konkoly optical observations
  34. GRB 150323A; Konkoly optical observations
  35. Konus-Wind observation of GRB 150323B
  36. GRB 150323C: Mondy optical observations
  37. GRB 150323C, Swift-BAT refined analysis
  38. GRB 150323C: Swift/UVOT Upper Limits
  39. GRB 150323B: Swift-XRT observations
  40. GRB 150323C: Enhanced Swift-XRT position
  41. GRB 150323C: RATIR Optical Afterglow Observations
  42. GRB 150323C: Swift-XRT refined Analysis
  43. GRB 150323C: Xingming upper limit
  44. GRB 150323A, Swift-BAT refined analysis
  45. GRB150323C: Fermi GBM detection
  46. GRB 150323C: Nanshan optical afterglow detection
  47. GRB 150323C: Swift detection of a burst
  48. GRB 150323A: Swift-XRT refined Analysis
  49. GRB150323A: Swift-UVOT detection of the afterglow
  50. GRB 150323A: Enhanced Swift-XRT position
  51. GRB 150314A: GMG observation limit
  52. GRB 150323A: RATIR Optical Afterglow Observations
  53. GRB 150323A: Swift detection of a burst
  54. GRB 150318A: Swift-XRT refined Analysis
  55. GRB 150318A: Skynet PROMPT-CTIO Observations
  56. GRB 150318A: Swift-BAT refined analysis
  57. GRB 150318A: Swift/UVOT Upper Limits
  58. GRB 150318A : GROND upper limits
  59. Swift Trigger 635306 is probably not an astrophysical source
  60. GRB 150318A: Enhanced Swift-XRT position
  61. GRB 150318A: Swift detection of a burst
  62. GRB 150317A: Swift/UVOT Upper Limits
  63. GRB 150317A: Swift-XRT refined Analysis
  64. GRB 150317A: Swift-BAT refined analysis
  65. GRB 150317A: RATIR Optical Afterglow Detection
  66. GRB 150317A: Enhanced Swift-XRT position
  67. GRB 150317A: NOT optical observations
  68. GRB 150317A: Swift detection of a burst
  69. GRB 150314A: Early RAPTOR Detection
  70. GRB 150220A, the review of the sky area in plate archives
  71. GRB 150314A: NOT further optical observations
  72. GRB 150314A: Swift-XRT refined Analysis
  73. GRB 150314A: Redshift from OSIRIS/GTC
  74. GRB 150314A: NOT optical observations
  75. GRB 150314A Swift-BAT refined analysis
  76. GRB 150314A: Swift/UVOT Detection
  77. GRB 150314A: Skynet Yerkes-41 Observations of the Optical Afterglow
  78. GRB 150314A: Enhanced Swift-XRT position
  79. GRB 150314A: Swift detection of a bright burst
  80. GRB 150313A: MAXI/GSC detection
  81. GRB 150309A: AAO optic upper limit
  82. GRB 150311A: MAXI/GSC possible afterglow detection
  83. GRB 150222A: CrAO optical observation
  84. GRB 150309A: CrAO optic upper limit
  85. GRB 150309A: ISON-Kislovodsk optic upper limit
  86. GRB 150309A: Swift-BAT refined analysis
  87. GRB 150309A: Fermi GBM detection
  88. GRB150309A: Optical observations at Crni Vrh
  89. GRB 150309A: Swift/UVOT Upper Limits
  90. GRB 150309A: MASTER prompt optical observation
  91. GRB 150309A: Swift-XRT refined Analysis
  92. GRB 150309A: Enhanced Swift-XRT position
  93. GRB 150309A: BOOTES-1 and -2 upper limit
  94. GRB 150309A: Swift detection of a burst
  95. GRB 150305A: a long GRB detected by INTEGRAL
  96. Swift J0045.2+4151: analysis of XMM-Newton archival data
  97. Further UVOT Observations of Swift J0045.2+4151
  98. Further X-ray observations of Swift J0045.2+4151 (aka Sw J0045 aka GRB 150301C aka [PFH2005] 622)
  99. BAT trigger 633105 (GRB 150301C): NOT r-band upper limit
  100. GRB 150302A: BOOTES-2/TELMA upper limit

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