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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. GRB 020409: Optical Observations
  2. GRB020406(?), optical observations
  3. GRB020410, optical observations
  4. BeppoSAX ALERT: possible GRB020410
  5. X-ray afterglow of GRB020321
  6. BeppoSAX GRB : GRB020409
  7. GRB020331: Confirmation of Afterglow Candidate with Magellan
  8. GRB020405: VLT optical observations and V band decay slope
  9. GRB020331 optical observations with RIMOTS
  10. GRB020124 optical observations with RIBOTS/RIMOTS
  11. GRB 020321: Candidate X-ray Counterparts
  12. ASM GRB candidate 020406 refined error box
  13. GRB 020405: Moderate-resolution spectroscopy
  14. GRB020331: Optical Observations of Afterglow Candidate
  15. GRB020406(?), optical observations
  16. GRB020405: VLT optical observations
  17. Revised Photometry of the Optical Afterglow of GRB 020405
  18. GRB020405: OT observations
  19. GRB 020331: Candidate Optical Afterglow
  20. GRB 020405: Decay index
  21. Short RXTE/ASM transient 020406; may be a GRB
  22. GRB020405, Radio Observations
  23. GRB020405: VLT spectroscopy
  24. Fading Optical Afterglow and Possible Host Galaxy of GRB 020405
  25. V band observations of GRB020405
  26. GRB 020405, U-band observations
  27. GRB 020405: Optical afterglow candidate
  28. IPN localization of GRB020405
  29. GRB011212: Optical Observations
  30. GRB 020331: NIR Observations
  31. GRB 020331: NIR Observations
  32. GRB020331 NIR observation at KPNO (re-submission)
  33. GRB02033 NIR observation at KPNO
  34. GRB020331 field photometry
  35. GRB 020331 Optical Observations
  36. GRB 020331, NIR observations
  37. GRB 020331: Optical observations
  38. GRB020331(=H1963): The "Easter" Burst Detected by HETE
  39. GRB 020321: Infrared observations
  40. GRB 020322: BeppoSAX observations of the X-ray afterglow
  41. SN 2002ap - peak brightness date (SN/GRB?)
  42. GRB011211: HST Observations of Optical Afterglow and Host Galaxy
  43. GRB 020322, Radio observations
  44. Near-Infrared Observations of GRB020322 at TIRGO
  45. GRB 020321, Radio Observations
  46. GRB 020322: Optical Observations
  47. GRB020127: Proposed Host Galaxy Detection and Identification of Afterglow
  48. GRB 020321: Optical observations
  49. GRB020317 BVRI field photometry
  50. GRB011211 revised BVRI field photometry
  51. GRB020305 BVRI field photometry
  52. GRB020322 BVRI field photometry
  53. GRB 020322 optical observations
  54. GRB020322: Candidate Optical Afterglow
  55. GRB 020322 optical observation
  56. GRB020317 : Near IR Observations from Mt Abu Observatory
  57. GRB 020322: Optical Sources and Improved Astrometry
  58. GRB020322, optical observations
  59. GRB 020322: Optical candidate
  60. XMM-Newton observation of GRB020322
  61. GRB020322: Optical Observations
  62. GRB020322: BeppoSAX/NFI Observations
  63. Bepposax GRB020322 The second springtime BSAX GRB
  64. GRB 020321: Optical observations
  65. GRB 011121: Fourth Epoch of HST Imaging
  66. GRB020317: optical observations
  67. GRB020321 optical observations
  68. GRB020321: BeppoSAX/NFI Observations
  69. GRB020321: a faint BeppoSAX detection
  70. GRB020305: NIR observations
  71. GRB 020317 : KISO Optical Observations
  72. BeppoSAX ALERT: GRB020321, the "Springtime Burst"
  73. GRB020317 (=H1959): Localization by HETE of a Low Fluence GRB
  74. GRB 020305: Optical Observations
  75. GRB020317, optical observations
  76. GRB 020317: Optical observations
  77. GRB 011121: Third HST Epoch
  78. GRB020305: Properties of the Candidate Optical Afterglow
  79. GRB 011121: HST Observations reveal an intermediate-time multicolor
  80. GRB011121, possible supernova association
  81. GRB011130 (XRF011130) Second Epoch Chandra Observations
  82. GRB020305: Subaru Optical Observations
  83. GRB 020305: Optical observations
  84. XRF/GRB 011030 Images
  85. XRF/GRB 011030: Detection of the Probable Host Galaxy
  86. GRB 020305: Candidate optical afterglow
  87. Type Ic SN2002bl (SN/GRB?) Radio Observations
  88. GRB020305, optical observations
  89. GRB020305: Optical Observations
  90. IPN triangulation of GRB020305 (HETE 1939)
  91. GRB020305 (=H1939): Localization of a GRB by HETE
  92. GRB 020305: Optical observations
  93. HST Imaging of the afterglow and host of GRB 011121
  94. GRB 010921: HST Observations
  95. IPN detection and localization of Cygnus X-1 flares
  96. GRB020127: Further VLA Observations of Possible Counterparts
  97. RXTE Observations of SGR 1900+14
  98. IPN detection of further SGR1900+14 activity
  99. SGR1900+14 activity
  100. IPN/HETE Detection of Bursts from SGR1900+14

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