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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"

36145 results found.

  1. SGR 1806-20: Temporal and Spectral behavior of radio transient
  2. SGR 1806-20, RHESSI observations of the 041227 giant flare
  3. SGR1806: Detection of a Sudden Ionospheric Disturbance
  4. GRB 041217: Optical observations
  5. GRB041219, early time observations
  6. IPN localization of giant flare from SGR1806-20
  7. GRB041219; RXTE ASM Observations
  8. NIR Observations of GRB 041219
  9. GRB041223: decay of the afterglow
  10. GRB 041224: near-infrared observations with REM
  11. GRB 041223: XRT afterglow spectrum and light curve
  12. GRB 041223 Fluence measured by Swift-BAT
  13. GRB041223: optical and NIR observations with REM
  14. GRB 041219: TAROT optical observations
  15. GRB 041218: TAROT optical observations
  16. GRB 041223: J-band observations of the afterglow
  17. GRB 041223: Detection of Optical Transient with LCO40
  18. GRB 041219c: PROMPT Observations
  19. GRB 041218: optical observations
  20. GRB 041219: Second Epoch WSRT Radio Observations
  21. GRB 041219: WSRT Radio Afterglow Detection
  22. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  23. GRB 041218: Optical observations
  24. GRB 041219 : optical follow-up observations
  25. Deep RAPTOR observations during GRB 041219
  26. GRB 041218 Optical Observations
  27. GRB 041219 Optical Observations
  28. GRB041219c: Third Burst in One Day from Swift-BAT
  29. GRB041219: Optical Afterglow Detection
  30. GRB041219: Continued NIR Observations
  31. GRB 041219 ,optical observation
  32. GRB 041219: Radio Afterglow Detection
  33. GRB 041218 : Radio Observations
  34. GRB 041218: R-band optical observations
  35. GRB041219: Confirmed NIR Afterglow
  36. GRB041218: Continued P60 Optical Observations
  37. GRB 041218: Optical Observation
  38. GRB 041219: Infrared Afterglow Candidate
  39. GRB041219, BVRcIc field calibration
  40. GRB 041219: Infrared Afterglow Candidate
  41. GRB041218, BVRcIc field calibration
  42. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  43. GRB041219: P60 Optical Observations
  44. GRB 041219 - A long GRB detected by INTEGRAL
  45. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  46. GRB 041217: PROMPT Observations
  47. GRB041218: optical observations
  48. GRB041217: optical limit 30 min after GRB
  49. GRB 041218; optical candidate
  50. GRB 041218: Optical observations
  51. GRB 041217: LCO40 Optical Observations and Possible Candidates
  52. GRB 041218 - A long GRB detected by integral
  53. GRB041217: Optical Observations
  54. GRB041217: P60 Optical Observations
  55. GRB041217: Infrared Observations
  56. GRB041217: The First GRB Located On-Board Swift
  57. GRB041211: Faulkes Telescope continued optical monitoring
  58. Optical Transient in Lynx not a GRB
  59. Optical transient (GRB?) in Lynx
  60. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  61. GRB041211: Continued P60 Observations
  62. GRB041211: RAPTOR observations
  63. GRB041211: Ashra Prototype optical observation
  64. GRB041211, Faulkes Telescope optical observation
  65. GRB041211, BVRcIc field calibration
  66. GRB 041211: Infrared Observations
  67. GRB 041211: KAIT observations
  68. GRB 041211: Optical follow-up in East Asian region
  69. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  70. GRB041211: P60 optical imaging
  71. GRB970815: Discovery of Optical Afterglow
  72. Distribution of IBAS Alerts for NON-GRB sources
  73. Triangulation of short GRB 041116 (large error box)
  74. GRB 040924: Afterglow Color
  75. GRB 041006: GETS Optical Afterglow Observation
  76. Summary of the recent bursts from SGR 1806-20
  77. GRB 041006: Optical Observations
  78. GRB041006, late-time optical photometry
  79. IBAS GRB Alert # 2034
  80. GRB041006: RTT150 Optical Observations
  81. Bright bursts from SGR1806-20
  82. GRB 041016: BOOTES-2 simultaneous observation
  83. GRB041006: RTT150 Optical Observations
  84. GRB 041016: Optical limits
  85. GRB 041016: Optical limits in V, R, I
  86. GRB 041016:Optical limit during first minute
  87. GRB041016: MASTER: Optical observations
  88. GRB 041015: Optical Observations at Rikubetsu
  89. GRB041006: Near Infrared observations
  90. GRB 041016: Optical limit
  91. GRB 041015 R band observations
  92. GRB040924, BVRcIc field calibration
  93. GRB041015: MASTER: Optical observations
  94. GRB041015,optical observation
  95. GRB 041015: Optical limit at Osaka University
  96. GRB041015 : Optical follow-up at Kiso
  97. GRB 041015 - A long GRB detected by INTEGRAL
  98. GRB 041006 R observations in Loiano
  99. GRB041006: VLT observations of the afterglow and host galaxy
  100. GRB041006: Optical observations and Potential host galaxy

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