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

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