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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"

43604 results found.

  1. Christmas GRB 141225A: GROND Observations
  2. GRB 141229A Tiled Swift observations
  3. GRB 141229A: MAXI/GSC detection
  4. GRB 141225A: MASTER-SAAO OT light curve
  5. GRB 141225A: TAROT Calern observatory optical observations
  6. GRB 141225A: Swift/UVOT refined analysis
  7. GRB 141225A: Fermi GBM detection
  8. GRB 141225A: very early T60 observations
  9. GRB 141225A: Swift-BAT refined analysis
  10. GRB 141225A: Swift-XRT refined Analysis
  11. GRB 141225A: MASTER-SAAO first OT detection
  12. GRB 141225A: Nanshan very early optical observations
  13. GRB 141225A: Enhanced Swift-XRT position
  14. GRB 141225A: Redshift from OSIRIS at the 10.4m GTC
  15. GRB 141225A: UVOT detection
  16. GRB 141225A: Optical aftergow confirmation
  17. GRB 141225A: LT optical candidate
  18. GRB 141225A: 1.23m CAHA optical observations
  19. GRB 141225A: Swift detection of a burst
  20. GRB 141221A: Keck spectroscopy
  21. GRB 141221A: TAROT La Silla observatory optical observations
  22. Swift XRT and UVOT observations of GRB141222A
  23. Konus-Wind observation of GRB 141222A
  24. GRB 141222A: First MASTER-SAAO optical observation
  25. IPN Triangulation of GRB 141222A (very intense)
  26. GRB 141221A: Continued Skynet PROMPT-CTIO observations
  27. GRB 141222A: Fermi GBM detection
  28. GRB 141221A: Swift/UVOT Detection
  29. GRB 141222A: Fermi-LAT detection
  30. GRB 141215A: further Swift-XRT observations and afterglow detection
  31. GRB 141221A: Fermi GBM observation
  32. GRB 141221A: Swift-XRT refined Analysis
  33. GRB 141221A: Swift-BAT refined analysis
  34. GRB141221A: GROND Afterglow Detection
  35. GRB 141221A: Enhanced Swift-XRT position
  36. GRB 141221A: Skynet PROMPT-CTIO observations of the optical afterglow
  37. GRB 141221A: LCOGT-McDonald optical afterglow observations
  38. GRB141221A: REM afterglow
  39. Konus-Wind observation of GRB 141220A
  40. GRB 141221A: Swift detection of a burst with an optical counterpart
  41. GRB 141220A: Fermi GBM observation
  42. GRB 141220A: Swift-XRT refined Analysis
  43. GRB 141220A: Swift-BAT refined analysis
  44. GRB 141220A: Swift/UVOT Detection
  45. GRB 141220A: Photometry from OSIRIS/GTC
  46. GRB 141220A: LT optical afterglow observations
  47. GRB 141220A: Redshift from OSIRIS at the 10.4m GTC
  48. GRB141220A: 1.23m CAHA I-band observations
  49. GRB 141220A: Swift detection of a burst with an optical afterglow
  50. Fermi Gamma-ray Burst Monitor trigger 440728127 / 141220020 is not a GRB
  51. IPN Triangulation of GRB 141207A
  52. GRB 141207A: Suzaku WAM observation of the prompt emission
  53. GRB 141202A: Suzaku WAM observation of the prompt emission
  54. GRB 141121A: Keck observations
  55. GRB 141215A: Swift-XRT observations
  56. GRB 141215A: Fermi GBM detection
  57. GRB 141215A Tiled Swift observations
  58. Konus-Wind observation of GRB 141215A
  59. IPN Triangulation of GRB 141215A (long/intense)
  60. GRB 141212A iTelescope observation
  61. GRB 141212A: Zadko observatory - Gingin optical observations
  62. Konus-Wind observation of GRB 141212B
  63. GRB 141212B: Swift-XRT refined Analysis
  64. GRB 141212A: VLA upper limit
  65. GRB 141212A: Gemini-N spectroscopy and photometry
  66. GRB 141212B: Swift-BAT refined analysis
  67. GRB 141212A: Swift-BAT refined analysis
  68. GRB 141212B: Enhanced Swift-XRT position
  69. Swift detection of 4U 1700+24 (= V934 Her)
  70. GRB 141212A: Swift-XRT refined Analysis
  71. GRB 141212A: extended object within the XRT error circle
  72. GRB 141212A: Khureltogot optical upper limit
  73. GRB 141212A: 1.23m CAHA I-band observations
  74. GRB 141212B: initial Swift/UVOT observations
  75. GRB 141212B: Swift/XRT preliminary localization
  76. GRB 141212A: Enhanced Swift-XRT position
  77. GRB 141212A: MASTER early optical observations
  78. GRB 141212A: Skynet R-COP Observations
  79. GRB 141212B: Swift detection of a burst
  80. GRB 141212A: Swift detection of a short burst
  81. GRB 141207A: Swift-XRT afterglow candidate detection
  82. GRB 141121A: further VLA observations
  83. Konus-Wind observation of GRB 141207A
  84. GRB141208.63: MASTER OT Detection During the Fermi Error Box inspection
  85. GRB141202A: Discovery Channel Telescope Optical Observations
  86. GRB141207A: Discovery Channel Telescope Optical Observations
  87. GRB 141207A: Swift-UVOT Observations
  88. GRB 141207A: Fermi GBM detection
  89. GRB 141207A: Swift-XRT observations
  90. Konus-Wind observation of GRB 141130A
  91. GRB 141207A Tiled Swift observations
  92. GRB 141207A: Fermi-LAT Detection
  93. GRB141121A: Discovery Channel Telescope Optical Observations
  94. GRB 141205A: Fermi GBM detection
  95. GRB 141205A: Nanshan optical upper limit
  96. GRB 141205A: XRT observations
  97. GRB 141205A Swift-BAT refined analysis
  98. GRB 141202A: Swift/UVOT Detection of a Variable Source Near the IPN Error Box
  99. GRB 141121A: Mondy optical observations
  100. GRB 141205A Short hard GRB found in ground analysis of BAT data

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