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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"

36131 results found.

  1. GRB 041218: TAROT optical observations
  2. GRB 041223: J-band observations of the afterglow
  3. GRB 041223: Detection of Optical Transient with LCO40
  4. GRB 041219c: PROMPT Observations
  5. GRB 041218: optical observations
  6. GRB 041219: Second Epoch WSRT Radio Observations
  7. GRB 041219: WSRT Radio Afterglow Detection
  8. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  9. GRB 041218: Optical observations
  10. GRB 041219 : optical follow-up observations
  11. Deep RAPTOR observations during GRB 041219
  12. GRB 041218 Optical Observations
  13. GRB 041219 Optical Observations
  14. GRB041219c: Third Burst in One Day from Swift-BAT
  15. GRB041219: Optical Afterglow Detection
  16. GRB041219: Continued NIR Observations
  17. GRB 041219 ,optical observation
  18. GRB 041219: Radio Afterglow Detection
  19. GRB 041218 : Radio Observations
  20. GRB 041218: R-band optical observations
  21. GRB041219: Confirmed NIR Afterglow
  22. GRB041218: Continued P60 Optical Observations
  23. GRB 041218: Optical Observation
  24. GRB 041219: Infrared Afterglow Candidate
  25. GRB041219, BVRcIc field calibration
  26. GRB 041219: Infrared Afterglow Candidate
  27. GRB041218, BVRcIc field calibration
  28. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  29. GRB041219: P60 Optical Observations
  30. GRB 041219 - A long GRB detected by INTEGRAL
  31. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  32. GRB 041217: PROMPT Observations
  33. GRB041218: optical observations
  34. GRB041217: optical limit 30 min after GRB
  35. GRB 041218; optical candidate
  36. GRB 041218: Optical observations
  37. GRB 041217: LCO40 Optical Observations and Possible Candidates
  38. GRB 041218 - A long GRB detected by integral
  39. GRB041217: Optical Observations
  40. GRB041217: P60 Optical Observations
  41. GRB041217: Infrared Observations
  42. GRB041217: The First GRB Located On-Board Swift
  43. GRB041211: Faulkes Telescope continued optical monitoring
  44. Optical Transient in Lynx not a GRB
  45. Optical transient (GRB?) in Lynx
  46. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  47. GRB041211: Continued P60 Observations
  48. GRB041211: RAPTOR observations
  49. GRB041211: Ashra Prototype optical observation
  50. GRB041211, Faulkes Telescope optical observation
  51. GRB041211, BVRcIc field calibration
  52. GRB 041211: Infrared Observations
  53. GRB 041211: KAIT observations
  54. GRB 041211: Optical follow-up in East Asian region
  55. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  56. GRB041211: P60 optical imaging
  57. GRB970815: Discovery of Optical Afterglow
  58. Distribution of IBAS Alerts for NON-GRB sources
  59. Triangulation of short GRB 041116 (large error box)
  60. GRB 040924: Afterglow Color
  61. GRB 041006: GETS Optical Afterglow Observation
  62. Summary of the recent bursts from SGR 1806-20
  63. GRB 041006: Optical Observations
  64. GRB041006, late-time optical photometry
  65. IBAS GRB Alert # 2034
  66. GRB041006: RTT150 Optical Observations
  67. Bright bursts from SGR1806-20
  68. GRB 041016: BOOTES-2 simultaneous observation
  69. GRB041006: RTT150 Optical Observations
  70. GRB 041016: Optical limits
  71. GRB 041016: Optical limits in V, R, I
  72. GRB 041016:Optical limit during first minute
  73. GRB041016: MASTER: Optical observations
  74. GRB 041015: Optical Observations at Rikubetsu
  75. GRB041006: Near Infrared observations
  76. GRB 041016: Optical limit
  77. GRB 041015 R band observations
  78. GRB040924, BVRcIc field calibration
  79. GRB041015: MASTER: Optical observations
  80. GRB041015,optical observation
  81. GRB 041015: Optical limit at Osaka University
  82. GRB041015 : Optical follow-up at Kiso
  83. GRB 041015 - A long GRB detected by INTEGRAL
  84. GRB 041006 R observations in Loiano
  85. GRB041006: VLT observations of the afterglow and host galaxy
  86. GRB041006: Optical observations and Potential host galaxy
  87. GRB041006, BVRcIc field calibration
  88. GRB 040924: VLT spectroscopy
  89. GRB 041006: SARA afterglow observations
  90. Search for SN light in XRF 040912 with MEGACAM
  91. GRB 040916: Afterglow Color at Early Times
  92. GRB 041006 Optical afterglow observations
  93. IBAS GRB Alert # 2010
  94. GRB 041006: BR observations with VATT
  95. GRB 041006: Redshift confirmed
  96. GRB041006: Liverpool Telescope optical observations
  97. GRB 041006: Colour measurement
  98. GRB041006: break in the light curve
  99. GRB 041006: Radio Observations
  100. GRB041006, further submilllimetre observations

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