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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"

32825 results found.

  1. GRB 041219: WSRT Radio Afterglow Detection
  2. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  3. GRB 041218: Optical observations
  4. GRB 041219 : optical follow-up observations
  5. Deep RAPTOR observations during GRB 041219
  6. GRB 041218 Optical Observations
  7. GRB 041219 Optical Observations
  8. GRB041219c: Third Burst in One Day from Swift-BAT
  9. GRB041219: Optical Afterglow Detection
  10. GRB041219: Continued NIR Observations
  11. GRB 041219 ,optical observation
  12. GRB 041219: Radio Afterglow Detection
  13. GRB 041218 : Radio Observations
  14. GRB 041218: R-band optical observations
  15. GRB041219: Confirmed NIR Afterglow
  16. GRB041218: Continued P60 Optical Observations
  17. GRB 041218: Optical Observation
  18. GRB 041219: Infrared Afterglow Candidate
  19. GRB041219, BVRcIc field calibration
  20. GRB 041219: Infrared Afterglow Candidate
  21. GRB041218, BVRcIc field calibration
  22. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  23. GRB041219: P60 Optical Observations
  24. GRB 041219 - A long GRB detected by INTEGRAL
  25. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  26. GRB 041217: PROMPT Observations
  27. GRB041218: optical observations
  28. GRB041217: optical limit 30 min after GRB
  29. GRB 041218; optical candidate
  30. GRB 041218: Optical observations
  31. GRB 041217: LCO40 Optical Observations and Possible Candidates
  32. GRB 041218 - A long GRB detected by integral
  33. GRB041217: Optical Observations
  34. GRB041217: P60 Optical Observations
  35. GRB041217: Infrared Observations
  36. GRB041217: The First GRB Located On-Board Swift
  37. GRB041211: Faulkes Telescope continued optical monitoring
  38. Optical Transient in Lynx not a GRB
  39. Optical transient (GRB?) in Lynx
  40. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  41. GRB041211: Continued P60 Observations
  42. GRB041211: RAPTOR observations
  43. GRB041211: Ashra Prototype optical observation
  44. GRB041211, Faulkes Telescope optical observation
  45. GRB041211, BVRcIc field calibration
  46. GRB 041211: Infrared Observations
  47. GRB 041211: KAIT observations
  48. GRB 041211: Optical follow-up in East Asian region
  49. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  50. GRB041211: P60 optical imaging
  51. GRB970815: Discovery of Optical Afterglow
  52. Distribution of IBAS Alerts for NON-GRB sources
  53. Triangulation of short GRB 041116 (large error box)
  54. GRB 040924: Afterglow Color
  55. GRB 041006: GETS Optical Afterglow Observation
  56. Summary of the recent bursts from SGR 1806-20
  57. GRB 041006: Optical Observations
  58. GRB041006, late-time optical photometry
  59. IBAS GRB Alert # 2034
  60. GRB041006: RTT150 Optical Observations
  61. Bright bursts from SGR1806-20
  62. GRB 041016: BOOTES-2 simultaneous observation
  63. GRB041006: RTT150 Optical Observations
  64. GRB 041016: Optical limits
  65. GRB 041016: Optical limits in V, R, I
  66. GRB 041016:Optical limit during first minute
  67. GRB041016: MASTER: Optical observations
  68. GRB 041015: Optical Observations at Rikubetsu
  69. GRB041006: Near Infrared observations
  70. GRB 041016: Optical limit
  71. GRB 041015 R band observations
  72. GRB040924, BVRcIc field calibration
  73. GRB041015: MASTER: Optical observations
  74. GRB041015,optical observation
  75. GRB 041015: Optical limit at Osaka University
  76. GRB041015 : Optical follow-up at Kiso
  77. GRB 041015 - A long GRB detected by INTEGRAL
  78. GRB 041006 R observations in Loiano
  79. GRB041006: VLT observations of the afterglow and host galaxy
  80. GRB041006: Optical observations and Potential host galaxy
  81. GRB041006, BVRcIc field calibration
  82. GRB 040924: VLT spectroscopy
  83. GRB 041006: SARA afterglow observations
  84. Search for SN light in XRF 040912 with MEGACAM
  85. GRB 040916: Afterglow Color at Early Times
  86. GRB 041006 Optical afterglow observations
  87. IBAS GRB Alert # 2010
  88. GRB 041006: BR observations with VATT
  89. GRB 041006: Redshift confirmed
  90. GRB041006: Liverpool Telescope optical observations
  91. GRB 041006: Colour measurement
  92. GRB041006: break in the light curve
  93. GRB 041006: Radio Observations
  94. GRB041006, further submilllimetre observations
  95. GRB 041006 : optical follow-up observation at Lulin Observatory
  96. GRB 041006 : Optical follow-up observation at TAROT
  97. GRB041006: Optical photometry and spectroscopy at TNG
  98. GRB 041006: presice astrometry
  99. GRB041006 (= H3570): Chandra Observations In Progress
  100. GRB 041006 : optical observation at Bisei

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