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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"

38396 results found.

  1. GRB 020321, Radio Observations
  2. GRB020127: Proposed Host Galaxy Detection and Identification of Afterglow
  3. GRB 020321: Optical observations
  4. GRB020317 BVRI field photometry
  5. GRB011211 revised BVRI field photometry
  6. GRB020305 BVRI field photometry
  7. GRB020322 BVRI field photometry
  8. GRB 020322 optical observations
  9. GRB020322: Candidate Optical Afterglow
  10. GRB 020322 optical observation
  11. GRB020317 : Near IR Observations from Mt Abu Observatory
  12. GRB 020322: Optical Sources and Improved Astrometry
  13. GRB020322, optical observations
  14. GRB 020322: Optical candidate
  15. GRB020322: Optical Observations
  16. GRB020322: BeppoSAX/NFI Observations
  17. Bepposax GRB020322 The second springtime BSAX GRB
  18. GRB 020321: Optical observations
  19. GRB 011121: Fourth Epoch of HST Imaging
  20. GRB020317: optical observations
  21. GRB020321 optical observations
  22. GRB020321: a faint BeppoSAX detection
  23. GRB020305: NIR observations
  24. GRB 020317 : KISO Optical Observations
  25. BeppoSAX ALERT: GRB020321, the "Springtime Burst"
  26. GRB020317 (=H1959): Localization by HETE of a Low Fluence GRB
  27. GRB 020305: Optical Observations
  28. GRB020317, optical observations
  29. GRB 020317: Optical observations
  30. GRB 011121: Third HST Epoch
  31. GRB020305: Properties of the Candidate Optical Afterglow
  32. GRB 011121: HST Observations reveal an intermediate-time multicolor
  33. GRB011121, possible supernova association
  34. GRB011130 (XRF011130) Second Epoch Chandra Observations
  35. GRB020305: Subaru Optical Observations
  36. GRB 020305: Optical observations
  37. XRF/GRB 011030: Detection of the Probable Host Galaxy
  38. GRB 020305: Candidate optical afterglow
  39. Type Ic SN2002bl (SN/GRB?) Radio Observations
  40. GRB020305, optical observations
  41. IPN triangulation of GRB020305 (HETE 1939)
  42. GRB020305 (=H1939): Localization of a GRB by HETE
  43. GRB 020305: Optical observations
  44. HST Imaging of the afterglow and host of GRB 011121
  45. GRB 010921: HST Observations
  46. IPN detection and localization of Cygnus X-1 flares
  47. GRB020127: Further VLA Observations of Possible Counterparts
  48. RXTE Observations of SGR 1900+14
  49. IPN detection of further SGR1900+14 activity
  50. SGR1900+14 activity
  51. IPN/HETE Detection of Bursts from SGR1900+14
  52. IPN Upper Limits to a GRB Associated With SN2002ap
  53. GRB020124 BVRI field photometry
  54. GRB020127: Palomar and VLA Observations of Possible Counterparts
  55. GRB020127: Comparison of Chandra Epochs and Identification of Possible Counterparts
  56. SN2002ap (SN/GRB?) Echelle spectra
  57. SN2002ap (SN/GRB?) optical spectrographic observations
  58. GRB020127, WSRT radio observations
  59. GRB020127 Optical Observations
  60. SN 2002ap (SN/GRB?)
  61. SN 2002ap in M74
  62. SN2002ap (SN/GRB?) UBVRI Field Photometry
  63. GRB020127: Chandra Observations and Prospective Counterparts
  64. pre-SN2002ap (SN/GRB?) imaging of M74
  65. SN 2002ap (hypernova / GRB ??): special list on VSNET
  66. Type Ib/c SN2002ap (SN/GRB?)
  67. Type Ib/c SN2002ap (SN/GRB?) Radio Observations
  68. GRB 020127, I-band observations starting 3.14-hr after the event
  69. IPN detection of further activity from SGR1806-20
  70. IPN triangulation of GRB020127 (=H1902)
  71. GRB010921 Optical Observations
  72. GRB020127(=H1902): Localization of a Double-Peaked GRB by HETE
  73. GRB020124: Optical observations
  74. VLT observations of GRB 020124: The fading optical/near-infrared afterglow
  75. GRB020124: Optical observations
  76. GRB 020124: Optical observations
  77. GRB 020124 Optical Observations
  78. IPN triangulation of GRB020124 (HETE 1896)
  79. IPN observations of SGR1806-20
  80. GRB 020124: Optical afterglow
  81. GRB020124(=H1896): Localization of a Long GRB by HETE
  82. HETE 1896: Optical observations
  83. GRB optical counterpart candidate in GCN 1217 is M dwarf
  84. Possible optical counterpart to a GRB
  85. GRB011212, Optical Observations
  86. Optical polarization observations for GRB011211
  87. GRB 011211: Detection of the Probable Host Galaxy
  88. GRB 011130 and GRB 011212 - Milagro GeV/TeV Observations
  89. GRB 011211, spectrum and optical photometry
  90. GRB 011130: Optical Observations of X-ray and Radio Sources
  91. GRB 011130, Radio/X-ray Comparison
  92. GRB011212: Optical observations
  93. GRB 011212: optical observation at Asiago
  94. GRB 011211: Evidence for an Optical Break
  95. GRB 011211: TNG Spectroscopic Observations
  96. optical follow-up of GRB(XRF) 011211
  97. GRB 011212: optical observation at Oslo (relayed)
  98. GRB 011211: Optical Spectroscopy
  99. GRB 011211, Optical Observations
  100. GRB011212, BVRI field photometry

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