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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. MASTER: GRB040827 possible OT
  2. GRB 040825B: Optical observations
  3. GRB040827 optical observations
  4. GRB 040827 : Planned XMM-Newton observation
  5. GRB 040827 - Refined position
  6. GRB 040827 : peak flux
  7. GRB 040827 - A long GRB detected by INTEGRAL
  8. GRB040825B, BVRcIc field photometry
  9. GRB040825A, BVRcIc field photometry
  10. GCN GRB OBSERBATION REPORT
  11. GRB 040825A,optical observations
  12. Increase of SGR 1806-20 activity
  13. GRB040825A: optical observations
  14. GRB040825B: optical observations
  15. GRB040825B (=H3510): An XRF Localized in Real Time by HETE
  16. GRB 040825A: Optical observations.
  17. MASTER: GRB040825a optical observation
  18. MASTER: GRB040825b optical observation
  19. GRB040825B: Correction to GCN 2657
  20. GRB 040825: Optical observations
  21. XRF040812: possible afterglow second Chandra observation
  22. GRB 040812: Second epoch CXO Observations
  23. GRB040823,optical observation
  24. XRF040812: GMRT observations
  25. Triangulation of GRB 040816 (Konus-Wind - Helicon-Coronas-F)
  26. XRF 040812: optical observation at VLT
  27. GRB 040812: Optical counterparts of CXO sources
  28. XRF040812: possible afterglow
  29. CXO observation of GRB 040812
  30. Bursting activity from SGR 1806-20 detected with IBAS
  31. IPN/HETE localizations of GRB040810 (=H3489)
  32. GRB 040812: Keck and LCO optical observations
  33. GRB 040812: Keck and LCO observations
  34. GRB 040812: radio observations
  35. GRB040812, optical/IR observations
  36. Konus-Wind observation of GRB040810 (=H3489)
  37. GRB 040812: a long GRB detected by INTEGRAL
  38. GRB 040810: Optical observations of a limited region
  39. XRF040701: Optical Observations at ESO
  40. IPN/HETE triangulation of GRB040802 (=H3485)
  41. GRB 040730, infrared observations
  42. GRB 040730: Optical observations
  43. GRB 040730: a long GRB detected with INTEGRAL
  44. Ongoing activity of SGR 1806-20
  45. GRB040624: optical monitoring at TNG
  46. XRF 040701 - optical observations of the decaying Chandra source
  47. XRF040701: Second-Epoch Chandra Observations
  48. Cancellation of IBAS/INTEGRAL GRB alerts
  49. XRF040701: VLA Observations
  50. XRF040701: Magellan Spectroscopy of Chandra Source #2 Associated Galaxy
  51. XRF040701: First-Epoch Chandra Observations
  52. IBAS Alert 1836: NOT a real GRB
  53. GRB040709 J,H-band observations
  54. GRB040624, optical observations
  55. GRB040706:observation at University of Miyazaki
  56. XRF 040701, optical observations
  57. XRF040701 (=U11548): a bright XRF detected by HETE
  58. GRB 040624: optical observations
  59. Optical Observations of GRB040624
  60. GRB 040624: optical observations at TNG and VLT
  61. MASTER: GRB 040624 optical observation after 0,48d
  62. GRB 040624: R-band observations
  63. GRB 040624, optical observations
  64. GRB 040624 - A long GRB detected with INTEGRAL
  65. GRB 030329: Rebrightening of hyperluminal ejecta.
  66. IPN Summary of SGR1806-20 Activity in 2004
  67. GRB040511: Retraction of redshift identification
  68. SGR 1806-20: no IR variability of the proposed counterparts
  69. MASTER:HETE Alert 3259 (SRG1806-20) optical observation
  70. SGR 1806-20, potential NIR counterpart
  71. GRB 040606: Optical observations
  72. MASTER: HETE Alert 3274 optical observation
  73. Activivty of SGR 1806-20
  74. IPN triangulation of an intense intermediate burst from SGR1806-20
  75. GRB 040511, very fast decay?
  76. GRB 030324: Detection and Color of Host Galaxy
  77. GRB 040511: NIR observations with REM
  78. GRB040511: Redshift identifcation
  79. GRB 040511: Optical limit
  80. GRB040511: Candidate optical/NIR afterglow
  81. IBAS GRB Alerts n.1785 to 1791
  82. GRB 040511: ROTSE-III Rapid Optical Upper Limits
  83. GRB 040511: Second Epoch Optical Observations
  84. IBAS GRB Alerts 1781-4
  85. GRB 040511: Optical observations
  86. GRB 040511: Optical Observations
  87. GRB040511: Optical Observations
  88. GRB040511: Optical Observations
  89. GRB040511 (=H3218): A Long GRB Localized by HETE WXM and SXC
  90. IBAS GRB Alert number 1774: NOT a real GRB
  91. Type Ic SN2001em (off-axis GRB jet?), optical spectrum
  92. IBAS Alerts 1771 and 1772: NOT a real GRB
  93. GRB and XRF on April 27, 2004. Detection by Konus-Wind and Helicon (Coronas-F)
  94. IPN triangulation of GRB040425 (=H3183)
  95. On Line Availability of Archival HETE Fregate Data and Lightcurves
  96. GRB040422: optical observations at Xinglong Observatory
  97. GRB040422: optical observations at CrAO
  98. GRB 040423 (=H3175): A Long GRB Localized by HETE
  99. GRB040422, optical observations at Loiano
  100. GRB040422 : I-band follow-up observation at Lulin Observatory

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