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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"

36134 results found.

  1. GRB 041223 Fluence measured by Swift-BAT
  2. GRB041223: optical and NIR observations with REM
  3. GRB 041219: TAROT optical observations
  4. GRB 041218: TAROT optical observations
  5. GRB 041223: J-band observations of the afterglow
  6. GRB 041223: Detection of Optical Transient with LCO40
  7. GRB 041219c: PROMPT Observations
  8. GRB 041218: optical observations
  9. GRB 041219: Second Epoch WSRT Radio Observations
  10. GRB 041219: WSRT Radio Afterglow Detection
  11. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  12. GRB 041218: Optical observations
  13. GRB 041219 : optical follow-up observations
  14. Deep RAPTOR observations during GRB 041219
  15. GRB 041218 Optical Observations
  16. GRB 041219 Optical Observations
  17. GRB041219c: Third Burst in One Day from Swift-BAT
  18. GRB041219: Optical Afterglow Detection
  19. GRB041219: Continued NIR Observations
  20. GRB 041219 ,optical observation
  21. GRB 041219: Radio Afterglow Detection
  22. GRB 041218 : Radio Observations
  23. GRB 041218: R-band optical observations
  24. GRB041219: Confirmed NIR Afterglow
  25. GRB041218: Continued P60 Optical Observations
  26. GRB 041218: Optical Observation
  27. GRB 041219: Infrared Afterglow Candidate
  28. GRB041219, BVRcIc field calibration
  29. GRB 041219: Infrared Afterglow Candidate
  30. GRB041218, BVRcIc field calibration
  31. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  32. GRB041219: P60 Optical Observations
  33. GRB 041219 - A long GRB detected by INTEGRAL
  34. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  35. GRB 041217: PROMPT Observations
  36. GRB041218: optical observations
  37. GRB041217: optical limit 30 min after GRB
  38. GRB 041218; optical candidate
  39. GRB 041218: Optical observations
  40. GRB 041217: LCO40 Optical Observations and Possible Candidates
  41. GRB 041218 - A long GRB detected by integral
  42. GRB041217: Optical Observations
  43. GRB041217: P60 Optical Observations
  44. GRB041217: Infrared Observations
  45. GRB041217: The First GRB Located On-Board Swift
  46. GRB041211: Faulkes Telescope continued optical monitoring
  47. Optical Transient in Lynx not a GRB
  48. Optical transient (GRB?) in Lynx
  49. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  50. GRB041211: Continued P60 Observations
  51. GRB041211: RAPTOR observations
  52. GRB041211: Ashra Prototype optical observation
  53. GRB041211, Faulkes Telescope optical observation
  54. GRB041211, BVRcIc field calibration
  55. GRB 041211: Infrared Observations
  56. GRB 041211: KAIT observations
  57. GRB 041211: Optical follow-up in East Asian region
  58. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  59. GRB041211: P60 optical imaging
  60. GRB970815: Discovery of Optical Afterglow
  61. Distribution of IBAS Alerts for NON-GRB sources
  62. Triangulation of short GRB 041116 (large error box)
  63. GRB 040924: Afterglow Color
  64. GRB 041006: GETS Optical Afterglow Observation
  65. Summary of the recent bursts from SGR 1806-20
  66. GRB 041006: Optical Observations
  67. GRB041006, late-time optical photometry
  68. IBAS GRB Alert # 2034
  69. GRB041006: RTT150 Optical Observations
  70. Bright bursts from SGR1806-20
  71. GRB 041016: BOOTES-2 simultaneous observation
  72. GRB041006: RTT150 Optical Observations
  73. GRB 041016: Optical limits
  74. GRB 041016: Optical limits in V, R, I
  75. GRB 041016:Optical limit during first minute
  76. GRB041016: MASTER: Optical observations
  77. GRB 041015: Optical Observations at Rikubetsu
  78. GRB041006: Near Infrared observations
  79. GRB 041016: Optical limit
  80. GRB 041015 R band observations
  81. GRB040924, BVRcIc field calibration
  82. GRB041015: MASTER: Optical observations
  83. GRB041015,optical observation
  84. GRB 041015: Optical limit at Osaka University
  85. GRB041015 : Optical follow-up at Kiso
  86. GRB 041015 - A long GRB detected by INTEGRAL
  87. GRB 041006 R observations in Loiano
  88. GRB041006: VLT observations of the afterglow and host galaxy
  89. GRB041006: Optical observations and Potential host galaxy
  90. GRB041006, BVRcIc field calibration
  91. GRB 040924: VLT spectroscopy
  92. GRB 041006: SARA afterglow observations
  93. Search for SN light in XRF 040912 with MEGACAM
  94. GRB 040916: Afterglow Color at Early Times
  95. GRB 041006 Optical afterglow observations
  96. IBAS GRB Alert # 2010
  97. GRB 041006: BR observations with VATT
  98. GRB 041006: Redshift confirmed
  99. GRB041006: Liverpool Telescope optical observations
  100. GRB 041006: Colour measurement

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