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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. XMM observations of the short GRB120804A
  2. GRB 120819A: optical upper limit
  3. GRB 120802A: optical observations in CrAO
  4. GRB 120830A: Further Swift Observations
  5. GRB 120830A: catalog source at Uvot position
  6. GRB 120830A: Swift-XRT and UVOT observations
  7. GRB 120830A: Fermi GBM observation
  8. Konus-Wind observation of GRB 120830A
  9. GRB 120830A: early MASTER optical limit
  10. IPN Triangulation of short GRB 120830A
  11. GRB 120830A: Fermi-LAT detection of a short burst
  12. Fermi trigger 368003226 : MASTER optical observations
  13. GRB 120819A: Swift/UVOT Upper Limits
  14. GRB 120817A: Swift/UVOT Upper Limits
  15. GRB 120817B: Deep limit on the optical afterglow from du Pont and Magellan observations
  16. GRB 120821A: Swift/XRT observations
  17. GRB 120821A: Swift/UVOT Upper Limits
  18. GRB 120821A: GROND upper limits
  19. GRB 120821A: a long GRB detected by INTEGRAL
  20. GRB 120817B - PTF Observations
  21. GRB 120817A: RAPTOR Limits During Gamma-Ray Emitting Interval
  22. GRB 120811C: optical observations
  23. GRB 120817B: BAT location in ground analysis and refined analysis
  24. GRB 120819A: MASTER final limits
  25. GRB 120819A: Bassano Bresciano Observatory optical observations
  26. GRB 120819A: Swift-BAT refined analysis
  27. GRB 120819A: GROND afterglow confirmation
  28. GRB 120819A: Swift-XRT refined Analysis
  29. GRB 120819A: MITSuME Ishigakijima upper limits
  30. GRB 120819A: MITSuME Okayama Optical upper limits
  31. GRB 120819A: Enhanced Swift-XRT position
  32. GRB 120819A: afterglow candidate from NOT
  33. GRB 120819A: MASTER optical observations
  34. GRB 120819A: Swift detection of a burst
  35. GRB 120817B: Swift-XRT observations
  36. GRB 120811C: optical observations
  37. GRB 120816A: Swift/UVOT Detection of the Optical Afterglow
  38. GRB 120815A: MASTER-ICATE observations
  39. Konus-Wind observation of GRB 120816B
  40. IPN Triangulation of GRB 120816B (short/exceptionally intense)
  41. Konus-Wind observation of GRB 120817B
  42. GRB 120817A: Swift-XRT refined Analysis
  43. GRB 120817B: LCO Optical Observations
  44. GRB 120817B: Fermi GBM detection
  45. IPN Triangulation of GRB 120817B (short/very intense)
  46. GRB 120817A: Swift-BAT refined analysis
  47. GRB 120816A: optical upper limit
  48. GRB 120817A: Enhanced Swift-XRT position
  49. GRB 120815A: Swift/UVOT Detection of the Optical Afterglow
  50. GRB 120816A: Bassano Bresciano Observatory optical observations
  51. GRB 120817A: FTN and FTS observations
  52. GRB 120816A: Swift-XRT refined Analysis
  53. GRB 120817A: Swift-XRT observations
  54. GRB 120817A: Swift detection of a burst
  55. GRB 120816A: Enhanced Swift-XRT position
  56. GRB 120816A: Swift-BAT refined analysis
  57. GRB 120816A: BOOTES-2 observations
  58. GRB120816A: OPTIMA discovery of optical counterpart
  59. GRB 120816A: TAROT Calern observatory optical observations
  60. GRB 120816A: ROTSE-III Optical Limits
  61. GRB 120816A: Swift detection of a burst
  62. GRB 120815A: Swift-XRT refined Analysis
  63. GRB 120815A: Swift-BAT refined analysis
  64. GRB 120805A: Liverpool Telescope optical candidate detection
  65. GRB 120815A: Enhanced Swift-XRT position
  66. GRB 120815A: VLT/X-shooter redshift
  67. GRB 120815A: GROND afterglow candidate
  68. GRB 120815A: Swift-XRT observations
  69. GRB 120815A: TAROT La Silla observatory optical observations
  70. GRB 120815A: Swift detection of a burst
  71. GRB 120811B: Fermi GBM observation
  72. GRB 120804A: Possible temporal break in the X-ray light-curve
  73. GCN for GRB 120811C
  74. GRB 120811A: Swift/XRT-UVOT Obseravations
  75. GRB120804A: Chandra observations and afterglow detection
  76. GRB 120805A: optical afterglow confirmation from the NOT
  77. GRB 120805A: Enhanced Swift-XRT position
  78. GRB 120811C: EVLA Observations
  79. GRB 120811C: RTT150 optical observations
  80. GRB 120811C: MASTER-Tunka OT observations
  81. GRB 120811C: Swift-BAT refined analysis
  82. GRB 120811A: Swift-BAT refined analysis
  83. GRB 120811C: NOT redshift
  84. GRB 120811C: Bassano Bresciano Observatory optical observations
  85. GRB 120811C: Swift-XRT refined Analysis
  86. GRB 120811C: Swift/UVOT Detection
  87. GRB 120811C: Redshift from OSIRIS/GTC
  88. Improved IPN error box for short hard GRB 120811B
  89. GRB 120811C: RTT150 optical observations
  90. GRB 120811C: Enhanced Swift-XRT position
  91. GRB 120811C: TAROT Calern observatory optical observations
  92. GRB 120811C: MASTER-Amur observations of fading OT
  93. GRB 120811C: Swift detection of a burst with an optical counterpart
  94. Konus-Wind observation of GRB 120811B
  95. IPN Triangulation of short hard GRB 120811B
  96. Trigger 530588: Swift detection of XMM J174457-2850.3
  97. Swift Trigger 530581: GRB 120811A or a galactic transient
  98. GRB 120803A: optical upper limit
  99. GRB 120807A: Swift/UVOT Upper Limits
  100. GRB 120803A: Confirmation of the X-ray afterglow

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