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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').
  1. GRB050315: Radio afterglow
  2. GRB 050315: Absorption redshift
  3. GRB 050315: Optical afterglow identification
  4. GRB050315: Swift-BAT Refined analysis
  5. Non-detection of GRB050315 in ATCA Radio Observations
  6. GRB 050315: Swift XRT Position
  7. GRB 050219b: Gemini/GNIRS near-infrared spectroscopy
  8. GRB 050315: Early Observations with Swift/UVOT
  9. Swift-BAT detection of GRB 050315
  10. GRB050223: No XMM-Newton OM detection of afterglow emission
  11. GRB 050306: Radio Observations
  12. GRB050306: 250 GHz upper limit with MAMBO at the IRAM 30m
  13. GRB050309: CONCAM pre-trigger and trigger coincident optical
  14. GRB 050306: optical afterglow
  15. GRB 050126: Redshift determination
  16. Swift-BAT trigger 107873: No Swift XRT counterpart
  17. GRB 050306: Confirmation of X-ray afterglow
  18. GRB 050309, Early optical limits from RAPTOR
  19. GRB 050306: further TAROT optical data
  20. GRB050309: Early optical limit from P60
  21. Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
  22. GRB 050309 : Lulin R-band observation
  23. Swift 107873: P60 Optical Observations
  24. GRB 050306: CORRECTION to date of observation
  25. GRB 050306: R-band observations
  26. GRB 050306: No Swift UVOT Optical Counterpart Detected
  27. GRB 050306: REM optical-infrared observations
  28. GRB 050306: Possible X-ray Afterglow Position from the Swift
  29. Swift trigger 107518: optical observation
  30. GRB 050306: TAROT optical observations
  31. GRB 050306,optical observation
  32. GRB 050306: Swift-BAT detection of a long burst
  33. Ongoing activity of SGR 1806-20 after the giant flare
  34. GRB050215B: Late-Time Swift UVOT Observations
  35. GRB 050126: Confirmation of the NIR afterglow candidate
  36. PROMPT VRcIc Observations of GRB 050223
  37. XRF/GRB 050215B: Radio Observations
  38. XMM-Newton Images of GRB 050223
  39. GRB 050219b: candidate NIR afterglow
  40. IBAS GRB Alert #2321
  41. Confirmed XRF nature for GRB050215b
  42. GRB 050223: optical observations
  43. GRB050223 XMM-Newton observation
  44. INTEGRAL detection of GRB 050223
  45. GRB 050223 : Planned XMM-Newton observation
  46. GRB050223: No Swift UVOT Detection of Afterglow Emission
  47. GRB050223: ROTSE-III Optical Observations
  48. GRB 050223 Swift/BAT detection of a burst
  49. GRB 050223: Swift XRT Position
  50. HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash
  51. GRB050219b: CORRECTION to time of UVOT observations
  52. GRB050215b: Faulkes North and SDSS limits on UKIRT candidate
  53. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  54. GRB 050219b: CORRECTION to refined XRT position
  55. GRB 050219a: Optical observations from LCO
  56. GRB 050219b: Optical and near-IR observations from LCO
  57. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  58. GRB 050219b: Refined XRT position
  59. GRB 050219b: Swift-BAT detection of a burst
  60. GRB 050219b: CORRECTION: Swift XRT Position
  61. GRB 050219b: Swift XRT Position
  62. GRB 050219a, optical observations
  63. GRB 050219a: Refined XRT position
  64. GRB050219a: No Swift UVOT Detection of Afterglow Emission
  65. GRB 050219: Swift-BAT detection of a burst
  66. GRB050215b: Swift UVOT Detection of Afterglow Emission
  67. GRB 050219: Prompt X-ray position
  68. GRB 050215B: Radio Observations
  69. GRB 050215b: XRT confirmation of IR afterglow candidate
  70. GRB050215b: P60 Optical Observations
  71. GRB 050215b: Swift XRT Source Variability
  72. GRB 050215B: candidate afterglow
  73. GRB 050215b : Lulin follow-up observation
  74. GRB 050215b, BOOTES-2 simultaneous optical observations
  75. GRB 050215B: UKIRT K-band imaging
  76. GRB 050215b: Swift XRT Observations
  77. GRB050215b: No Swift UVOT Detection of Afterglow Emission
  78. GRB050215a: No Swift UVOT Detection of Afterglow Emission
  79. Swift-BAT detects two bursts: GRB050215a and GRB050215b
  80. GRB 050215b, BOOTES-1B optical limit
  81. GRB050215B: ROTSE-III optical observations
  82. GRB050215A: ROTSE-III Optical Observations
  83. GRB050209: TAROT optical observations
  84. GRB 050209(=U11568): Duration and spectrum
  85. short/hard GRB 050202, optical observations
  86. GRB050209: REM optical observations
  87. GRB 050209 I-band observation
  88. GRB 050209 Optical observations
  89. GRB050209: P60 Optical Observations
  90. GRB050209 (=U11568): A Long GRB Detected by HETE
  91. GRB 050209: Optical observation
  92. GRB 050128: Radio observations
  93. Further analysis of the short Swift-BAT GRB 050202
  94. GRB 050202: Second epoch radio observations
  95. GRB 050129: Optical observations
  96. GRB050202: Radio Observations
  97. GRB 050202: Optical observations with LCO40
  98. GRB 050202: Short burst detected by Swift-BAT
  99. GRB 050128 Optical observation with REM
  100. GRB 050129: a weak long GRB detected with INTEGRAL

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