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

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