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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 070328: Swift/XRT Refined Analysis
  2. GRB 070328 : Suzaku ToO follow up starts
  3. GRB 070328, Swift-BAT refined analysis
  4. GRB 070328: Swift detection of a burst
  5. GRB070220: optical observations
  6. GRB070208: optical observations
  7. GRB070223: confirmation of nIR and optical afterglow
  8. GRB070318: Swift UVOT indicates unusual optical/UV afterglow
  9. GRB 070311, deep optical photometry
  10. Short-Hard GRB 070209: PROMPT Observations
  11. GRB 070318: Gemini + Magellan spectra
  12. GRB 070318: absorption-line redshift
  13. GRB070318: Swift UVOT continuing observations
  14. GRB070318: Swift-XRT refined analysis
  15. GRB 070318: Swift/UVOT Continued Observations
  16. GRB 070318, Swift-BAT refined analysis
  17. IBAS Alert n. 4176: not a GRB
  18. GRB 070318: Swift detection of a burst with an optical afterglow
  19. GRB 070311: Late Central Engine Activity Optical Flare??
  20. GRB 070311: MDM Optical Monitoring
  21. VLA observation of GRB 070311
  22. GRB 070311: Tautenburg sees afterglow fading
  23. IBAS Alert n. 4169: not a GRB
  24. GRB 070311: Optical observation.
  25. GRB 070311: Optical Brightening
  26. GRB 070306: possible emission-line redshift
  27. GRB 070311: SARA upper limit
  28. GRB 070309: variability of the XRT afterglow candidate
  29. GRB 070311: MDM Optical Follow-up
  30. GRB 070311: RAPTOR Detection of Optical Emission
  31. GRB070311: FRAM early follow-up limit
  32. GRB 070311: P60 Observations
  33. GRB 070311: MDM Optical Detection
  34. GRB 070311: Swift/UVOT Upper Limits
  35. GRB 070311: MITSuME Okayama Optical Observation
  36. GRB 070311: Swift-XRT refined analysis
  37. GRB 070311: PAIRITEL confirmation of variability of REM candidate
  38. GRB 070311: REM candidate afterglow
  39. GRB 070311: a long GRB detected by INTEGRAL
  40. GRB060901: Candidate optical afterglow
  41. GRB070309: Swift/XRT possible afterglow detection
  42. GRB 070125: Chandra X-ray Confirmation of Jet Break
  43. GRB 070309: Swift/UVOT Upper Limits
  44. GRB 070306, optical observation
  45. Swift UVOT Finding Charts for GRB 070309
  46. GRB 070309: A long GRB detected by INTEGRAL
  47. GRB 070125: X-ray light curve analysis
  48. VLA observation of GRB 070306
  49. IBAS Alert 4162: Not a GRB
  50. GRB 070306: NOT observations
  51. GRB 070306 Swift/UVOT refined analysis
  52. GRB070306: confirmation of near infrared afterglow
  53. GRB 070306: ART-3 early optical and near infrared constraints
  54. GRB 070306: IR observations and candidate afterglow
  55. GRB 070306, Swift-BAT refined analysis
  56. GRB 070306: XRT Team Refined Analysis
  57. GRB 070306: Optical and IR observations with KANATA
  58. GRB070306 - SDSS Pre-burst Observations
  59. GRB 070306: Swift detection of a burst
  60. GRB 070223: NIR observations at WHT
  61. GRB070227: Swift-XRT refined analysis
  62. GRB 060605 new redshift
  63. GRB 070125, deep late-time optical observation
  64. VLA observation of GRB 070224
  65. GRB 070227: optical observations
  66. GRB 070223: Optical Observations
  67. GRB 070227: optical observations
  68. GRB 070227: Swift/UVOT Upper Limits
  69. GRB 070227: TAROT La Silla observatory optical observations
  70. GRB 070227, Swift-BAT refined analysis
  71. GRB070227: possible X-ray afterglow detection
  72. GRB 070227: Swift detection of a burst in ground analysis
  73. GRB 920925C: optical afterglow candidate
  74. GRB 070224: Optical afterglow confirmation
  75. IBAS Alert n. 4144: not a GRB
  76. GRB 070224: Swift/UVOT Upper Limits
  77. GRB070224: Swift-XRT Astrometrically Corrected Position
  78. VLA observation of GRB 070223
  79. VLA observation of GRB 070220
  80. GRB070224: Magellan Imaging Observations
  81. GRB 070224: WHT K-band imaging
  82. GRB 070224: MDM Observations
  83. GRB070224: Gemini Imaging Observations
  84. GRB 070224: SARA upper limit
  85. GRB070224: Swift-XRT Refined Analysis
  86. GRB 070224: optical afterglow candidate
  87. GRB 070224, Swift-BAT refined analysis
  88. GRB 070224: MASTER-Net refind analysis
  89. GRB 070224: MASTER-VWF-Kislovodsk observations
  90. GRB 070224: MASTER observations
  91. GRB 070224: Swift detection of a burst
  92. GRB 070223: Optical observations
  93. RHESSI Spectrum of GRB070220
  94. GRB070223: Swift/UVOT refined analysis
  95. GRB 070223: Optical-IR observation with KANATA
  96. GRB 070223, Swift-BAT refined analysis
  97. GRB070223: MASTER-VWF-Kislovodsk observations
  98. GRB 070223: Swift-XRT Refined Analysis
  99. GRB 070220: pseudo-z~2.15 from spectral parameters of the prompt
  100. GRB070223 - SDSS Pre-Burst Observations

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