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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. GRB060901: Candidate optical afterglow
  2. GRB070309: Swift/XRT possible afterglow detection
  3. GRB 070125: Chandra X-ray Confirmation of Jet Break
  4. GRB 070309: Swift/UVOT Upper Limits
  5. GRB 070306, optical observation
  6. Swift UVOT Finding Charts for GRB 070309
  7. GRB 070309: A long GRB detected by INTEGRAL
  8. GRB 070125: X-ray light curve analysis
  9. VLA observation of GRB 070306
  10. IBAS Alert 4162: Not a GRB
  11. GRB 070306: NOT observations
  12. GRB 070306 Swift/UVOT refined analysis
  13. GRB070306: confirmation of near infrared afterglow
  14. GRB 070306: ART-3 early optical and near infrared constraints
  15. GRB 070306: IR observations and candidate afterglow
  16. GRB 070306, Swift-BAT refined analysis
  17. GRB 070306: XRT Team Refined Analysis
  18. GRB 070306: Optical and IR observations with KANATA
  19. GRB070306 - SDSS Pre-burst Observations
  20. GRB 070306: Swift detection of a burst
  21. GRB 070223: NIR observations at WHT
  22. GRB070227: Swift-XRT refined analysis
  23. GRB 060605 new redshift
  24. GRB 070125, deep late-time optical observation
  25. VLA observation of GRB 070224
  26. GRB 070227: optical observations
  27. GRB 070223: Optical Observations
  28. GRB 070227: optical observations
  29. GRB 070227: Swift/UVOT Upper Limits
  30. GRB 070227: TAROT La Silla observatory optical observations
  31. GRB 070227, Swift-BAT refined analysis
  32. GRB070227: possible X-ray afterglow detection
  33. GRB 070227: Swift detection of a burst in ground analysis
  34. GRB 920925C: optical afterglow candidate
  35. GRB 070224: Optical afterglow confirmation
  36. IBAS Alert n. 4144: not a GRB
  37. GRB 070224: Swift/UVOT Upper Limits
  38. GRB070224: Swift-XRT Astrometrically Corrected Position
  39. VLA observation of GRB 070223
  40. VLA observation of GRB 070220
  41. GRB070224: Magellan Imaging Observations
  42. GRB 070224: WHT K-band imaging
  43. GRB 070224: MDM Observations
  44. GRB070224: Gemini Imaging Observations
  45. GRB 070224: SARA upper limit
  46. GRB070224: Swift-XRT Refined Analysis
  47. GRB 070224: optical afterglow candidate
  48. GRB 070224, Swift-BAT refined analysis
  49. GRB 070224: MASTER-Net refind analysis
  50. GRB 070224: MASTER-VWF-Kislovodsk observations
  51. GRB 070224: MASTER observations
  52. GRB 070224: Swift detection of a burst
  53. GRB 070223: Optical observations
  54. RHESSI Spectrum of GRB070220
  55. GRB070223: Swift/UVOT refined analysis
  56. GRB 070223: Optical-IR observation with KANATA
  57. GRB 070223, Swift-BAT refined analysis
  58. GRB070223: MASTER-VWF-Kislovodsk observations
  59. GRB 070223: Swift-XRT Refined Analysis
  60. GRB 070220: pseudo-z~2.15 from spectral parameters of the prompt
  61. GRB070223 - SDSS Pre-Burst Observations
  62. GRB 070223: Liverpool Telescope Possible Afterglow Candidate
  63. GRB 070223: MDM Observations
  64. GRB070223: Swift burst
  65. Konus-Wind and Konus-A observations of GRB 070220
  66. GRB 070220: MITSuME Okayama Optical Observation
  67. GRB 070220: ART-3 Optical and NIR limits
  68. GRB 070220 Swift-BAT Refined Analysis
  69. Swift/UVOT refined analysis of GRB070220
  70. GRB 070209: Swift XRT refined analysis
  71. GRB 070220: Swift-XRT Refined Analysis
  72. GRB 070220: Observation with the KANATA 1.5m telescope
  73. GRB 070219: Gemini Observations
  74. GRB 070220 : Faulkes Telescope North optical limit
  75. GRB 070220: Swift detection of a burst
  76. GRB070219: MASTER-VWF-Kislovodsk observations
  77. GRB 070219: XRT Refined Analysis
  78. GRB 070219: Swift/UVOT Upper limits
  79. GRB 070219: I-band observations
  80. GRB 070219, Swift-BAT refined analysis
  81. GRB 070219: optical TNG observations
  82. GRB 070219: Liverpool Telescope Observations
  83. GRB 070219: ROTSE-III Optical Limits
  84. GRB070219 - SDSS Pre-Burst Observations
  85. GRB 070219: Swift detection of a burst
  86. IPN triangulation of GRB070201 (refined error box using MESSENGER data)
  87. GRB 070125 observations with the GMRT
  88. GRB 070209: Redshift of a galaxy in the error circle of XRT source
  89. Swift-BAT trigger 260304 is NOT a burst or transient
  90. GRB 060927: PROMPT Observations
  91. GRB 070201: Correction to GCN 6094
  92. GRB 070129: MDM I-band Detection
  93. GRB 070125: Break in Optical Decay
  94. GRB 070209: Swift XRT analysis
  95. GRB 070201: clarification on localization and Konus-Wind spectra
  96. GRB070208: optical observations
  97. GRB 070201: IPN constraints and nearby galaxies
  98. GRB 070201: Proximity of IPN annulus to M31
  99. GRB 070208: MARGE Optical Observations
  100. IPN localization of very bright long hard GRB 070207

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