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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"

26188 results found.

  1. GRB 020321, Radio Observations
  2. GRB 020322: Optical Observations
  3. GRB020127: Proposed Host Galaxy Detection and Identification of Afterglow
  4. GRB 020321: Optical observations
  5. GRB020317 BVRI field photometry
  6. GRB011211 revised BVRI field photometry
  7. GRB020305 BVRI field photometry
  8. GRB020322 BVRI field photometry
  9. GRB 020322: Optical Sources and Improved Astrometry
  10. GRB020317: optical observations
  11. GRB020321 optical observations
  12. GRB020321: a faint BeppoSAX detection
  13. GRB 020317 : KISO Optical Observations
  14. GRB020317 (=H1959): Localization by HETE of a Low Fluence GRB
  15. GRB 020305: Optical Observations
  16. GRB020317, optical observations
  17. GRB 020317: Optical observations
  18. GRB 011121: Third HST Epoch
  19. GRB020305: Properties of the Candidate Optical Afterglow
  20. GRB 011121: HST Observations reveal an intermediate-time multicolor
  21. GRB011130 (XRF011130) Second Epoch Chandra Observations
  22. GRB020305: Subaru Optical Observations
  23. XRF/GRB 011030: Detection of the Probable Host Galaxy
  24. GRB 020305: Candidate optical afterglow
  25. GRB020305, optical observations
  26. IPN triangulation of GRB020305 (HETE 1939)
  27. GRB020305 (=H1939): Localization of a GRB by HETE
  28. HST Imaging of the afterglow and host of GRB 011121
  29. IPN detection and localization of Cygnus X-1 flares
  30. SGR1900+14 activity
  31. IPN Upper Limits to a GRB Associated With SN2002ap
  32. GRB020124 BVRI field photometry
  33. GRB020127: Comparison of Chandra Epochs and Identification of Possible Counterparts
  34. SN2002ap (SN/GRB?) Echelle spectra
  35. GRB020127 Optical Observations
  36. SN 2002ap in M74
  37. SN2002ap (SN/GRB?) UBVRI Field Photometry
  38. GRB020127: Chandra Observations and Prospective Counterparts
  39. pre-SN2002ap (SN/GRB?) imaging of M74
  40. Type Ib/c SN2002ap (SN/GRB?) Radio Observations
  41. GRB020124, optical observations
  42. GRB 020127, I-band observations starting 3.14-hr after the event
  43. GRB010921 Optical Observations
  44. GRB020127(=H1902): Localization of a Double-Peaked GRB by HETE
  45. GRB020124: Optical observations
  46. GRB 020124: Optical observations
  47. GRB 020124: Optical afterglow
  48. GRB020124(=H1896): Localization of a Long GRB by HETE
  49. Possible optical counterpart to a GRB
  50. GRB011212, Optical Observations
  51. Optical polarization observations for GRB011211
  52. GRB 011211: Detection of the Probable Host Galaxy
  53. GRB 011130 and GRB 011212 - Milagro GeV/TeV Observations
  54. GRB 011130: Optical Observations of X-ray and Radio Sources
  55. GRB 011212: optical observation at Asiago
  56. GRB 011211: Evidence for an Optical Break
  57. GRB 011211: TNG Spectroscopic Observations
  58. optical follow-up of GRB(XRF) 011211
  59. GRB 011212: optical observation at Oslo (relayed)
  60. GRB 011211, Optical Observations
  61. GRB011212, BVRI field photometry
  62. GRB011211, BVRI field photometry
  63. GRB011212 (=H10001): An X-Ray Rich GRB Detected by HETE
  64. Fading of the optical source associated of XRF 011211
  65. GRB 011211 Optical Observations: Likely Afterglow
  66. GRB011130 (=XRF011130): Further analysis of Chandra Target of
  67. GRB011130 (XRF011130) Chandra Observations
  68. GRB011130 (=XRF011130): Scheduled Target of Opportunity
  69. GRB 011130, K band observations
  70. GRB011130, optical observations
  71. GRB011130 (=XRF011130): Second Revised Localization by HETE
  72. GRB011130 (XRF011130) SDSS PT i-band observations
  73. XRF011130: Infrared Observations
  74. GRB 011121
  75. GRB011130 (=H1864): An X-Ray Rich GRB Detected by HETE
  76. GRB 011121: J-band observations
  77. GRB 011121: NIR observations, host galaxy?
  78. GRB011121: UBRI Observations
  79. GRB 011121 J-Band Astrometry
  80. GRB 011121: Detection of Bright IR Counterpart
  81. GRB011121: possible redshift, continued decay
  82. GRB 011030: TNG K-band observation
  83. XRF011030: J and K band observations
  84. XRF011030: Chandra Observations
  85. GRB011030: Z-band observations
  86. GRB 011030 R band observations
  87. GRB 011030 I-band Observation
  88. The X-ray Flash 011030 ('GRB 011030')
  89. Non-triggered burst 011030 ("GRB 011030")
  90. The Radio Afterglow from the X-ray Rich GRB 011030
  91. GRB 010921: HST Detection of the Afterglow and Host Galaxy
  92. GRB 970828: HST Observations of the Host Galaxy
  93. GRB 000131: HST Detection of the Host Galaxy
  94. GRB 970828: HST Observations of the Host Galaxy
  95. Optical observation of SGR 1806-20 at the 6-m SAO telescope
  96. GRB011019: Subaru Optical Observations
  97. GRB 011030 I-band Observations
  98. GRB 011030 K-band Observations
  99. GRB010921, optical observations
  100. GRB011030 - further refinement WFC position

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