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

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