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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. GRB 050319: NIR afterglow candidate
  2. GRB 050319:Near IR afterglow
  3. GRB050319: BR optical photometry
  4. GRB 050318: SWIFT-UVOT refined analysis
  5. GRB 050318: Absorption redshift from Magellan
  6. GRB 050319: Optical observation
  7. GRB 050319 : Confirmation of optical afterglow decay
  8. GRB 050319: Swift-BAT refined analysis
  9. GRB050319,optical observation
  10. Swift Detection of GRB 050319
  11. GRB 050319: Detection of Possible Optical Counterpart
  12. GRB 050318: Swift/UVOT detection of afterglow emission
  13. GRB 050318: Magellan optical afterglow identification
  14. GRB050318: Swift XRT position
  15. RXTE Observations of GRB050318
  16. Swift-BAT detection of GRB 050318
  17. GRB 050315, SMARTS optical afterglow decay
  18. GRB050223: analysis of the XMM-Newton observation
  19. GRB050316: MASTER before, simultanious and follow up optical
  20. GRB 050306: ROTSE-III early limits
  21. GRB050316: MASTER optical observations
  22. GRB 050315: Swift-BAT further refined analysis
  23. GRB 050315, SMARTS optical/IR afterglow observations
  24. GRB 050315 I-band observations
  25. GRB050315: Radio afterglow
  26. GRB 050315: Absorption redshift
  27. GRB 050315: Optical afterglow identification
  28. GRB050315: Swift-BAT Refined analysis
  29. Non-detection of GRB050315 in ATCA Radio Observations
  30. GRB 050315: Swift XRT Position
  31. GRB 050219b: Gemini/GNIRS near-infrared spectroscopy
  32. GRB 050315: Early Observations with Swift/UVOT
  33. Swift-BAT detection of GRB 050315
  34. GRB050223: No XMM-Newton OM detection of afterglow emission
  35. GRB 050306: Radio Observations
  36. GRB050306: 250 GHz upper limit with MAMBO at the IRAM 30m
  37. GRB050309: CONCAM pre-trigger and trigger coincident optical
  38. GRB 050306: optical afterglow
  39. GRB 050126: Redshift determination
  40. Swift-BAT trigger 107873: No Swift XRT counterpart
  41. GRB 050306: Confirmation of X-ray afterglow
  42. GRB 050309, Early optical limits from RAPTOR
  43. GRB 050306: further TAROT optical data
  44. GRB050309: Early optical limit from P60
  45. Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
  46. GRB 050309 : Lulin R-band observation
  47. Swift 107873: P60 Optical Observations
  48. GRB 050306: CORRECTION to date of observation
  49. GRB 050306: R-band observations
  50. GRB 050306: No Swift UVOT Optical Counterpart Detected
  51. GRB 050306: REM optical-infrared observations
  52. GRB 050306: Possible X-ray Afterglow Position from the Swift
  53. Swift trigger 107518: optical observation
  54. GRB 050306: TAROT optical observations
  55. GRB 050306,optical observation
  56. GRB 050306: Swift-BAT detection of a long burst
  57. Ongoing activity of SGR 1806-20 after the giant flare
  58. GRB050215B: Late-Time Swift UVOT Observations
  59. GRB 050126: Confirmation of the NIR afterglow candidate
  60. PROMPT VRcIc Observations of GRB 050223
  61. XRF/GRB 050215B: Radio Observations
  62. XMM-Newton Images of GRB 050223
  63. GRB 050219b: candidate NIR afterglow
  64. IBAS GRB Alert #2321
  65. Confirmed XRF nature for GRB050215b
  66. GRB 050223: optical observations
  67. GRB050223 XMM-Newton observation
  68. INTEGRAL detection of GRB 050223
  69. GRB 050223 : Planned XMM-Newton observation
  70. GRB050223: No Swift UVOT Detection of Afterglow Emission
  71. GRB050223: ROTSE-III Optical Observations
  72. GRB 050223 Swift/BAT detection of a burst
  73. GRB 050223: Swift XRT Position
  74. HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash
  75. GRB050219b: CORRECTION to time of UVOT observations
  76. GRB050215b: Faulkes North and SDSS limits on UKIRT candidate
  77. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  78. GRB 050219b: CORRECTION to refined XRT position
  79. GRB 050219a: Optical observations from LCO
  80. GRB 050219b: Optical and near-IR observations from LCO
  81. GRB050219b: No Swift UVOT Detection of Afterglow Emission
  82. GRB 050219b: Refined XRT position
  83. GRB 050219b: Swift-BAT detection of a burst
  84. GRB 050219b: CORRECTION: Swift XRT Position
  85. GRB 050219b: Swift XRT Position
  86. GRB 050219a, optical observations
  87. GRB 050219a: Refined XRT position
  88. GRB050219a: No Swift UVOT Detection of Afterglow Emission
  89. GRB 050219: Swift-BAT detection of a burst
  90. GRB050215b: Swift UVOT Detection of Afterglow Emission
  91. GRB 050219: Prompt X-ray position
  92. GRB 050215B: Radio Observations
  93. GRB 050215b: XRT confirmation of IR afterglow candidate
  94. GRB050215b: P60 Optical Observations
  95. GRB 050215b: Swift XRT Source Variability
  96. GRB 050215B: candidate afterglow
  97. GRB 050215b : Lulin follow-up observation
  98. GRB 050215b, BOOTES-2 simultaneous optical observations
  99. GRB 050215B: UKIRT K-band imaging
  100. GRB 050215b: Swift XRT Observations

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