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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"

22062 results found.

  1. GRB 020317: Optical observations
  2. GRB 011121: Third HST Epoch
  3. GRB 011121: HST Observations reveal an intermediate-time multicolor
  4. GRB011121, possible supernova association
  5. GRB011130 (XRF011130) Second Epoch Chandra Observations
  6. GRB020305: Subaru Optical Observations
  7. GRB 020305: Optical observations
  8. XRF/GRB 011030: Detection of the Probable Host Galaxy
  9. GRB 020305: Candidate optical afterglow
  10. Type Ic SN2002bl (SN/GRB?) Radio Observations
  11. GRB020305, optical observations
  12. GRB020305: Optical Observations
  13. GRB 020305: Optical observations
  14. HST Imaging of the afterglow and host of GRB 011121
  15. GRB 010921: HST Observations
  16. GRB020127: Further VLA Observations of Possible Counterparts
  17. RXTE Observations of SGR 1900+14
  18. GRB020127: Palomar and VLA Observations of Possible Counterparts
  19. GRB020127: Comparison of Chandra Epochs and Identification of Possible Counterparts
  20. SN2002ap (SN/GRB?) Echelle spectra
  21. SN2002ap (SN/GRB?) optical spectrographic observations
  22. GRB020127, WSRT radio observations
  23. GRB020127 Optical Observations
  24. SN 2002ap in M74
  25. SN2002ap (SN/GRB?) UBVRI Field Photometry
  26. GRB020127: Chandra Observations and Prospective Counterparts
  27. Type Ib/c SN2002ap (SN/GRB?)
  28. Type Ib/c SN2002ap (SN/GRB?) Radio Observations
  29. GRB020124, optical observations
  30. GRB020127: Optical observations
  31. GRB 020127, I-band observations starting 3.14-hr after the event
  32. GRB020127 Optical Observations -- Erratum to GCN 1230
  33. GRB010921 Optical Observations
  34. GRB020124: Optical observations
  35. VLT observations of GRB 020124: The fading optical/near-infrared afterglow
  36. GRB020124: Optical observations
  37. GRB 020124: Optical observations
  38. GRB 020124 Optical Observations
  39. IPN observations of SGR1806-20
  40. GRB 020124: Optical afterglow
  41. HETE 1896: Optical observations
  42. GRB optical counterpart candidate in GCN 1217 is M dwarf
  43. Possible optical counterpart to a GRB
  44. GRB011212, Optical Observations
  45. Optical polarization observations for GRB011211
  46. GRB 011130 and GRB 011212 - Milagro GeV/TeV Observations
  47. GRB011212: Optical observations at Gunma
  48. GRB 011130: Optical Observations of X-ray and Radio Sources
  49. GRB 011130, Radio/X-ray Comparison
  50. GRB011212: Optical observations
  51. GRB 011212: optical observation at Asiago
  52. GRB 011211: TNG Spectroscopic Observations
  53. GRB 011211, Optical Observations
  54. GRB011212: Optical observations
  55. GRB 011211 Optical Observations: Likely Afterglow
  56. GRB011130 (=XRF011130): Further analysis of Chandra Target of
  57. GRB 011130: Optical Observations of Chandra Sources
  58. GRB 011130: Optical Observations of Chandra sources
  59. GRB011130 (XRF011130) Chandra Observations
  60. Sub-mm and Centimeter Detections of the Host Galaxy of GRB000418
  61. GRB011130, optical observations
  62. GRB 011130, K band observations
  63. GRB011130, optical observations
  64. GRB 011130 I-band Observation
  65. GRB011130 (XRF011130) optical observations
  66. GRB011130 (XRF011130) SDSS PT i-band observations
  67. XRF011130: Infrared Observations
  68. GRB011130, Radio Observations
  69. GRB011130 (=XRF011130), Optical Observations
  70. XRF011130: NEAT Optical Observations
  71. GRB 011121
  72. GRB 011121: J-band observations
  73. GRB 011121: NIR observations, host galaxy?
  74. GRB010921 - Milagro GeV/TeV Observations
  75. GRB 011121: HST Scheduled
  76. GRB011121: fainter still
  77. GRB011121: UBRI Observations
  78. GRB011121
  79. GRB 011121: Radio Observations
  80. GRB011121: continued decay
  81. GRB 011121: Detection of Bright IR Counterpart
  82. GRB011121: possible redshift, continued decay
  83. GRB011121: fading behavior
  84. GRB011121: possible optical counterpart
  85. GRB 011030: TNG K-band observation
  86. XRF011030: J and K band observations
  87. XRF011030: Chandra Observations
  88. GRB 011030: K-band observations
  89. GRB011030: Z-band observations
  90. GRB 011030 R band observations
  91. The X-ray Flash 011030 ('GRB 011030')
  92. Non-triggered burst 011030 ("GRB 011030")
  93. The Radio Afterglow from the X-ray Rich GRB 011030
  94. GRB 010921: HST Detection of the Afterglow and Host Galaxy
  95. GRB 970828: HST Observations of the Host Galaxy
  96. GRB 970828: HST Observations of the Host Galaxy
  97. GRB010921, optical observation
  98. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  99. GRB011019: Subaru Optical Observations
  100. GRB 011030 I-band Observations

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