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

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