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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 040825B: Optical observations
  2. GRB040827 optical observations
  3. GRB 040827 : Planned XMM-Newton observation
  4. GRB 040827 - Refined position
  5. GRB 040827 : peak flux
  6. GRB 040827 - A long GRB detected by INTEGRAL
  7. GRB040825B, BVRcIc field photometry
  8. GRB040825A, BVRcIc field photometry
  9. GCN GRB OBSERBATION REPORT
  10. GRB 040825A,optical observations
  11. Increase of SGR 1806-20 activity
  12. GRB040825A: optical observations
  13. GRB040825B: optical observations
  14. GRB040825B (=H3510): An XRF Localized in Real Time by HETE
  15. GRB 040825A: Optical observations.
  16. MASTER: GRB040825a optical observation
  17. MASTER: GRB040825b optical observation
  18. GRB040825B: Correction to GCN 2657
  19. GRB 040825: Optical observations
  20. XRF040812: possible afterglow second Chandra observation
  21. GRB 040812: Second epoch CXO Observations
  22. GRB040823,optical observation
  23. XRF040812: GMRT observations
  24. Triangulation of GRB 040816 (Konus-Wind - Helicon-Coronas-F)
  25. XRF 040812: optical observation at VLT
  26. GRB 040812: Optical counterparts of CXO sources
  27. XRF040812: possible afterglow
  28. CXO observation of GRB 040812
  29. Bursting activity from SGR 1806-20 detected with IBAS
  30. IPN/HETE localizations of GRB040810 (=H3489)
  31. GRB 040812: Keck and LCO optical observations
  32. GRB 040812: Keck and LCO observations
  33. GRB 040812: radio observations
  34. GRB040812, optical/IR observations
  35. Konus-Wind observation of GRB040810 (=H3489)
  36. GRB 040812: a long GRB detected by INTEGRAL
  37. GRB 040810: Optical observations of a limited region
  38. XRF040701: Optical Observations at ESO
  39. IPN/HETE triangulation of GRB040802 (=H3485)
  40. GRB 040730, infrared observations
  41. GRB 040730: Optical observations
  42. GRB 040730: a long GRB detected with INTEGRAL
  43. Ongoing activity of SGR 1806-20
  44. GRB040624: optical monitoring at TNG
  45. XRF 040701 - optical observations of the decaying Chandra source
  46. XRF040701: Second-Epoch Chandra Observations
  47. Cancellation of IBAS/INTEGRAL GRB alerts
  48. XRF040701: VLA Observations
  49. XRF040701: Magellan Spectroscopy of Chandra Source #2 Associated Galaxy
  50. XRF040701: First-Epoch Chandra Observations
  51. IBAS Alert 1836: NOT a real GRB
  52. GRB040709 J,H-band observations
  53. Subject: GRB040624, optical observations
  54. GRB040706:observation at University of Miyazaki
  55. XRF 040701, optical observations
  56. XRF040701 (=U11548): a bright XRF detected by HETE
  57. GRB 040624: optical observations
  58. Optical Observations of GRB040624
  59. GRB 040624: optical observations at TNG and VLT
  60. MASTER: GRB 040624 optical observation after 0,48d
  61. GRB 040624: R-band observations
  62. GRB 040624, optical observations
  63. GRB 040624 - A long GRB detected with INTEGRAL
  64. GRB 030329: Rebrightening of hyperluminal ejecta.
  65. IPN Summary of SGR1806-20 Activity in 2004
  66. GRB040511: Retraction of redshift identification
  67. SGR 1806-20: no IR variability of the proposed counterparts
  68. MASTER:HETE Alert 3259 (SRG1806-20) optical observation
  69. SGR 1806-20, potential NIR counterpart
  70. GRB 040606: Optical observations
  71. MASTER: HETE Alert 3274 optical observation
  72. Activivty of SGR 1806-20
  73. IPN triangulation of an intense intermediate burst from SGR1806-20
  74. GRB 040511, very fast decay?
  75. GRB 030324: Detection and Color of Host Galaxy
  76. GRB 040511: NIR observations with REM
  77. GRB040511: Redshift identifcation
  78. GRB 040511: Optical limit
  79. GRB040511: Candidate optical/NIR afterglow
  80. IBAS GRB Alerts n.1785 to 1791
  81. GRB 040511: ROTSE-III Rapid Optical Upper Limits
  82. GRB 040511: Second Epoch Optical Observations
  83. IBAS GRB Alerts 1781-4
  84. GRB 040511: Optical observations
  85. GRB 040511: Optical Observations
  86. GRB040511: Optical Observations
  87. GRB040511: Optical Observations
  88. GRB040511 (=H3218): A Long GRB Localized by HETE WXM and SXC
  89. IBAS GRB Alert number 1774: NOT a real GRB
  90. Type Ic SN2001em (off-axis GRB jet?), optical spectrum
  91. IBAS Alerts 1771 and 1772: NOT a real GRB
  92. GRB and XRF on April 27, 2004. Detection by Konus-Wind and Helicon (Coronas-F)
  93. IPN triangulation of GRB040425 (=H3183)
  94. On Line Availability of Archival HETE Fregate Data and Lightcurves
  95. GRB040422: optical observations at Xinglong Observatory
  96. GRB040422: optical observations at CrAO
  97. GRB 040423 (=H3175): A Long GRB Localized by HETE
  98. GRB040422, optical observations at Loiano
  99. GRB040422 : I-band follow-up observation at Lulin Observatory
  100. GRB 040422: ROTSE-IIIb Prompt Optical Limits

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