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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"

36144 results found.

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

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