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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"
  1. GRB041219: Optical Afterglow Detection
  2. GRB041219: Continued NIR Observations
  3. GRB041219b: A Swift-BAT burst
  4. GRB 041219 ,optical observation
  5. GRB 041219: Radio Afterglow Detection
  6. GRB 041218 : Radio Observations
  7. GRB 041218: R-band optical observations
  8. GRB041218: Liverpool Telescope optical observations
  9. GRB041218: optical observations
  10. GRB041219: Confirmed NIR Afterglow
  11. GRB041218: Continued P60 Optical Observations
  12. Swift-BAT detection of the bright long burst GRB041219
  13. GRB 041218: Optical Observation
  14. GRB 041219: Infrared Afterglow Candidate
  15. GRB041219, BVRcIc field calibration
  16. GRB 041219: Infrared Afterglow Candidate
  17. GRB041218, BVRcIc field calibration
  18. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  19. GRB041219: P60 Optical Observations
  20. GRB 041219 - A long GRB detected by INTEGRAL
  21. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  22. GRB 041217: PROMPT Observations
  23. GRB041218: optical observations
  24. GRB041217: optical limit 30 min after GRB
  25. GRB 041218; optical candidate
  26. GRB 041218: Optical observations
  27. GRB 041217: LCO40 Optical Observations and Possible Candidates
  28. GRB 041218 - A long GRB detected by integral
  29. GRB041217: Optical Observations
  30. GRB041217: NIR and optical observations with REM
  31. GRB041217: P60 Optical Observations
  32. GRB041217: Infrared Observations
  33. GRB041217: The First GRB Located On-Board Swift
  34. GRB041211: Faulkes Telescope continued optical monitoring
  35. Optical Transient in Lynx not a GRB
  36. Optical transient (GRB?) in Lynx
  37. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  38. GRB041211: Continued P60 Observations
  39. GRB041211: RAPTOR observations
  40. GRB041211: Ashra Prototype optical observation
  41. GRB041211, Faulkes Telescope optical observation
  42. GRB041211, BVRcIc field calibration
  43. GRB041211,optical observation
  44. GRB 041211: Infrared Observations
  45. GRB 041211: KAIT observations
  46. GRB 041211: Optical follow-up in East Asian region
  47. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  48. GRB041211: P60 optical imaging
  49. GRB970815: Discovery of Optical Afterglow
  50. Distribution of IBAS Alerts for NON-GRB sources
  51. Triangulation of short GRB 041116 (large error box)
  52. GRB041015: Near-Infrared observations
  53. GRB 040924: Afterglow Color
  54. GRB 041006: GETS Optical Afterglow Observation
  55. Summary of the recent bursts from SGR 1806-20
  56. GRB 041006: Optical Observations
  57. GRB041006, late-time optical photometry
  58. GRB041015, optical observation in CrAO
  59. IBAS GRB Alert # 2034
  60. GRB041006: RTT150 Optical Observations
  61. GRB041015 : Multi epoch optical observations
  62. HST Observations: XRF 040701 and 040812
  63. Bright bursts from SGR1806-20
  64. GRB 041016: BOOTES-2 simultaneous observation
  65. GRB041006: RTT150 Optical Observations
  66. GRB041016,optical observation
  67. GRB 041016: Optical limits
  68. GRB 041016: Optical limits in V, R, I
  69. GRB 041016:Optical limit during first minute
  70. GRB041016: MASTER: Optical observations
  71. GRB 041015: Optical Observations at Rikubetsu
  72. GRB041006: Near Infrared observations
  73. GRB 041016: Optical limit
  74. GRB 041015 R band observations
  75. GRB040924, BVRcIc field calibration
  76. GRB041015: MASTER: Optical observations
  77. GRB041015,optical observation
  78. GRB041006: Fading X-ray Afterglow Observed with Chandra
  79. GRB 041015: Optical limit at Osaka University
  80. GRB041015 : Optical follow-up at Kiso
  81. GRB 041015 - A long GRB detected by INTEGRAL
  82. GRB 041006 R observations in Loiano
  83. GRB041006: VLT observations of the afterglow and host galaxy
  84. GRB041006: Optical observations and Potential host galaxy
  85. GRB041006, BVRcIc field calibration
  86. GRB 040924: VLT spectroscopy
  87. GRB 041006: SARA afterglow observations
  88. GRB041006, optical observation in CrAO
  89. Search for SN light in XRF 040912 with MEGACAM
  90. GRB 040916: Afterglow Color at Early Times
  91. GRB 041006 Optical afterglow observations
  92. IBAS GRB Alert # 2010
  93. GRB 041006: BR observations with VATT
  94. GRB 041006: Redshift confirmed
  95. GRB041006: Liverpool Telescope optical observations
  96. GRB 041006: Colour measurement
  97. GRB041006: break in the light curve
  98. GRB 041006: Radio Observations
  99. GRB041006, further submilllimetre observations
  100. GRB 041006 : optical follow-up observation at Lulin Observatory

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