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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. GRB050309: Early optical limit from P60
  2. Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
  3. GRB 050309 : Lulin R-band observation
  4. Swift 107873: P60 Optical Observations
  5. GRB 050306: CORRECTION to date of observation
  6. GRB 050306: R-band observations
  7. GRB 050306: No Swift UVOT Optical Counterpart Detected
  8. GRB 050306: REM optical-infrared observations
  9. GRB 050306: Possible X-ray Afterglow Position from the Swift
  10. Swift trigger 107518: optical observation
  11. GRB 050306: TAROT optical observations
  12. GRB 050306,optical observation
  13. GRB 050306: Swift-BAT detection of a long burst
  14. Ongoing activity of SGR 1806-20 after the giant flare
  15. GRB050215B: Late-Time Swift UVOT Observations
  16. GRB 050126: Confirmation of the NIR afterglow candidate
  17. PROMPT VRcIc Observations of GRB 050223
  18. XRF/GRB 050215B: Radio Observations
  19. XMM-Newton Images of GRB 050223
  20. GRB 050219b: candidate NIR afterglow
  21. IBAS GRB Alert #2321
  22. Confirmed XRF nature for GRB050215b
  23. GRB 050223: optical observations
  24. GRB050223 XMM-Newton observation
  25. INTEGRAL detection of GRB 050223
  26. GRB 050223 : Planned XMM-Newton observation
  27. GRB050223: No Swift UVOT Detection of Afterglow Emission
  28. GRB050223: ROTSE-III Optical Observations
  29. GRB 050223 Swift/BAT detection of a burst
  30. GRB 050223: Swift XRT Position
  31. HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash
  32. GRB050219b: CORRECTION to time of UVOT observations
  33. GRB050215b: Faulkes North and SDSS limits on UKIRT candidate
  34. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  35. GRB 050219b: CORRECTION to refined XRT position
  36. GRB 050219a: Optical observations from LCO
  37. GRB 050219b: Optical and near-IR observations from LCO
  38. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  39. GRB 050219b: Refined XRT position
  40. GRB 050219b: Swift-BAT detection of a burst
  41. GRB 050219b: CORRECTION: Swift XRT Position
  42. GRB 050219b: Swift XRT Position
  43. GRB 050219a, optical observations
  44. GRB 050219a: Refined XRT position
  45. GRB050219a: No Swift UVOT Detection of Afterglow Emission
  46. GRB 050219: Swift-BAT detection of a burst
  47. GRB050215b: Swift UVOT Detection of Afterglow Emission
  48. GRB 050219: Prompt X-ray position
  49. GRB 050215B: Radio Observations
  50. GRB 050215b: XRT confirmation of IR afterglow candidate
  51. GRB050215b: P60 Optical Observations
  52. GRB 050215b: Swift XRT Source Variability
  53. GRB 050215B: candidate afterglow
  54. GRB 050215b : Lulin follow-up observation
  55. GRB 050215b, BOOTES-2 simultaneous optical observations
  56. GRB 050215B: UKIRT K-band imaging
  57. GRB 050215b: Swift XRT Observations
  58. GRB050215b: No Swift UVOT Detection of Afterglow Emission
  59. GRB050215a: No Swift UVOT Detection of Afterglow Emission
  60. Swift-BAT detects two bursts: GRB050215a and GRB050215b
  61. GRB 050215b, BOOTES-1B optical limit
  62. GRB050215B: ROTSE-III optical observations
  63. GRB050215A: ROTSE-III Optical Observations
  64. GRB050209: TAROT optical observations
  65. GRB 050209(=U11568): Duration and spectrum
  66. short/hard GRB 050202, optical observations
  67. GRB050209: REM optical observations
  68. GRB 050209 I-band observation
  69. GRB 050209 Optical observations
  70. GRB050209: P60 Optical Observations
  71. GRB050209 (=U11568): A Long GRB Detected by HETE
  72. GRB 050209: Optical observation
  73. GRB 050128: Radio observations
  74. Further analysis of the short Swift-BAT GRB 050202
  75. GRB 050202: Second epoch radio observations
  76. GRB 050129: Optical observations
  77. GRB050202: Radio Observations
  78. GRB 050202: Optical observations with LCO40
  79. GRB 050202: Short burst detected by Swift-BAT
  80. GRB 050128 Optical observation with REM
  81. GRB 050129: a weak long GRB detected with INTEGRAL
  82. SGR1806-20: Swift-BAT detection of a large normal burst
  83. GRB050128: Faulkes Telescope South observations
  84. GRB 050124: Radio Observations
  85. GRB 050128: near-infrared observations with REM
  86. GRB050128,optical observations
  87. GRB 050126: A NIR afterglow candidate in the revised XRT error circle
  88. GRB050126: Updated Swift XRT Position
  89. SGR 1806-20: GMRT results at 240 MHz band.
  90. SGR 1806-20: low frequency GMRT results of 2005 Jan 16.
  91. GRB 050126: Radio Observations
  92. GRB050128 Swift-BAT observations
  93. GRB 050128: Swift XRT prompt afterglow position
  94. HETE #3667: P60 Observations
  95. GRB 050124: K-band afterglow observations
  96. GRB050126: MASTER optical limit for KECK OT
  97. GRB050126: Burst Parameters Measured by BAT
  98. GRB050126: MASTER optical observations
  99. GRB 050126: Detection of NIR afterglow with Keck/NIRC
  100. GRB 050126: Prompt XRT detection and localization

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