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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. IPN triangulation of GRB040924 (H3564)
  2. GRB 040924(=H3564): A Short, Bright GRB Localized in Real Time by HETE
  3. GRB040924 (H3564): Optical afterglow candidate
  4. XRF 040912: Radio Observations
  5. XRF 040916: Radio Observations
  6. GRB040912(=H3557): Chandra Candidate X-ray Afterglow
  7. XRF040916: continuing decay of OT
  8. TAROT Observations of GRB 040916 (HETE #3558)
  9. GRB040912(=H3557): Candidate Optical Afterglow
  10. XRF040916, optical observations
  11. XRF040916: Optical Transient Candidate by Subaru
  12. GRB040916 optical limits 17 min after GRB
  13. XRF 040912, identification of CXO sources
  14. XRF 040912 (=H3557): Spectral and Temporal Properties
  15. XRF040916, Ic observations
  16. XRF040916: optical follow-up observations
  17. XRF040912, BVRcIc field calibration
  18. XRF040916, BVRcIc field calibration
  19. GRB040916: Archival optical observations
  20. XRF 040916, optical follow-up
  21. GRB040912(=H3557): Observations with the Chandra X-ray Observatory
  22. GRB040916: Optical observations
  23. ROTSE-IIIb Observations of GRB 040916 (HETE #3558)
  24. GRB040916 (= H3558): Improved Localization from HETE WXM
  25. GRB040916 (= H3558): A Long XRF Localized by HETE
  26. GRB040912 (= H3557): Chandra Observations Scheduled
  27. GRB 040912: Optical Observations
  28. GRB/XRF040912,optical observations
  29. GRB 040912, BVRI observations
  30. Optical observations of GRB/XRF 040912 = HETE 3557
  31. An intense burst from SGR1806-20
  32. GRB040912 : Kiso Optical follow-up observation
  33. IBAS GRB Alerts 1978-1980
  34. Optical observations of field of GRB040912
  35. HETE 3557: Optical observations
  36. GRB040912 (= H3557): A Long GRB or XRF Localized by HETE
  37. GRB 040827: XMM-Newton data
  38. GRB040903 - A XRF?
  39. GRB040827: analysis of the XMM-Newton observation
  40. GRB040903, REM near-IR observation
  41. GRB 040903 - INTEGRAL data analysis
  42. IBAS Alert 1974. Not a real GRB
  43. Very bright burst detected from SGR 1806-20
  44. ROTSE-III Rapid Response to possible GRB 040903 (INTEGRAL #1972)
  45. Possible GRB 040903 - further analysis
  46. Possible GRB 040903 detected with INTEGRAL
  47. GRB 040827 - Radio Observations
  48. XMM-Newton Images of GRB 040827
  49. GRB040825A: Optical observations
  50. GRB040825A: Optical observations
  51. GRB 040827: optical and NIR observations at the VLT
  52. GRB 040827: UKIRT - 2nd epoch K-band imaging
  53. GRB 040827: 2nd epoch of Magellan K-band imaging
  54. GRB 040827: K imaging - no evidence of variability
  55. GRB 040827: Detection of NIR afterglow
  56. GRB 040827: Possible detection of optical afterglow
  57. GRB 040827: RTT150 optical observations
  58. GRB040827 XMM-Newton observation
  59. GRB040825A: optical limit before GRB
  60. MASTER: GRB040827 possible OT
  61. GRB 040825B: Optical observations
  62. GRB040827 optical observations
  63. GRB 040827 : Planned XMM-Newton observation
  64. GRB 040827 - Refined position
  65. GRB 040827 : peak flux
  66. GRB 040827 - A long GRB detected by INTEGRAL
  67. GRB040825B, BVRcIc field photometry
  68. GRB040825A, BVRcIc field photometry
  69. GCN GRB OBSERBATION REPORT
  70. GRB 040825A,optical observations
  71. Increase of SGR 1806-20 activity
  72. GRB040825A: optical observations
  73. GRB040825B: optical observations
  74. GRB040825B (=H3510): An XRF Localized in Real Time by HETE
  75. GRB 040825A: Optical observations.
  76. MASTER: GRB040825a optical observation
  77. MASTER: GRB040825b optical observation
  78. GRB040825B: Correction to GCN 2657
  79. GRB 040825: Optical observations
  80. XRF040812: possible afterglow second Chandra observation
  81. GRB 040812: Second epoch CXO Observations
  82. GRB040823,optical observation
  83. XRF040812: GMRT observations
  84. Triangulation of GRB 040816 (Konus-Wind - Helicon-Coronas-F)
  85. XRF 040812: optical observation at VLT
  86. GRB 040812: Optical counterparts of CXO sources
  87. XRF040812: possible afterglow
  88. CXO observation of GRB 040812
  89. Bursting activity from SGR 1806-20 detected with IBAS
  90. IPN/HETE localizations of GRB040810 (=H3489)
  91. GRB 040812: Keck and LCO optical observations
  92. GRB 040812: Keck and LCO observations
  93. GRB 040812: radio observations
  94. GRB040812, optical/IR observations
  95. Konus-Wind observation of GRB040810 (=H3489)
  96. GRB 040812: a long GRB detected by INTEGRAL
  97. GRB 040810: Optical observations of a limited region
  98. XRF040701: Optical Observations at ESO
  99. IPN/HETE triangulation of GRB040802 (=H3485)
  100. GRB 040730, infrared observations

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