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

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