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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 040827: Possible detection of optical afterglow
  2. GRB 040827: RTT150 optical observations
  3. GRB040827 XMM-Newton observation
  4. GRB040825A: optical limit before GRB
  5. MASTER: GRB040827 possible OT
  6. GRB 040825B: Optical observations
  7. GRB040827 optical observations
  8. GRB 040827 : Planned XMM-Newton observation
  9. GRB 040827 - Refined position
  10. GRB 040827 : peak flux
  11. GRB 040827 - A long GRB detected by INTEGRAL
  12. GRB040825B, BVRcIc field photometry
  13. GRB040825A, BVRcIc field photometry
  14. GCN GRB OBSERBATION REPORT
  15. GRB 040825A,optical observations
  16. Increase of SGR 1806-20 activity
  17. GRB040825A: optical observations
  18. GRB040825B: optical observations
  19. GRB040825B (=H3510): An XRF Localized in Real Time by HETE
  20. GRB 040825A: Optical observations.
  21. MASTER: GRB040825a optical observation
  22. MASTER: GRB040825b optical observation
  23. GRB040825B: Correction to GCN 2657
  24. GRB 040825: Optical observations
  25. XRF040812: possible afterglow second Chandra observation
  26. GRB 040812: Second epoch CXO Observations
  27. GRB040823,optical observation
  28. XRF040812: GMRT observations
  29. Triangulation of GRB 040816 (Konus-Wind - Helicon-Coronas-F)
  30. XRF 040812: optical observation at VLT
  31. GRB 040812: Optical counterparts of CXO sources
  32. XRF040812: possible afterglow
  33. CXO observation of GRB 040812
  34. Bursting activity from SGR 1806-20 detected with IBAS
  35. IPN/HETE localizations of GRB040810 (=H3489)
  36. GRB 040812: Keck and LCO optical observations
  37. GRB 040812: Keck and LCO observations
  38. GRB 040812: radio observations
  39. GRB040812, optical/IR observations
  40. Konus-Wind observation of GRB040810 (=H3489)
  41. GRB 040812: a long GRB detected by INTEGRAL
  42. GRB 040810: Optical observations of a limited region
  43. XRF040701: Optical Observations at ESO
  44. IPN/HETE triangulation of GRB040802 (=H3485)
  45. GRB 040730, infrared observations
  46. GRB 040730: Optical observations
  47. GRB 040730: a long GRB detected with INTEGRAL
  48. Ongoing activity of SGR 1806-20
  49. GRB040624: optical monitoring at TNG
  50. XRF 040701 - optical observations of the decaying Chandra source
  51. XRF040701: Second-Epoch Chandra Observations
  52. Cancellation of IBAS/INTEGRAL GRB alerts
  53. XRF040701: VLA Observations
  54. XRF040701: Magellan Spectroscopy of Chandra Source #2 Associated Galaxy
  55. XRF040701: First-Epoch Chandra Observations
  56. IBAS Alert 1836: NOT a real GRB
  57. GRB040709 J,H-band observations
  58. Subject: GRB040624, optical observations
  59. GRB040706:observation at University of Miyazaki
  60. XRF 040701, optical observations
  61. XRF040701 (=U11548): a bright XRF detected by HETE
  62. GRB 040624: optical observations
  63. Optical Observations of GRB040624
  64. GRB 040624: optical observations at TNG and VLT
  65. MASTER: GRB 040624 optical observation after 0,48d
  66. GRB 040624: R-band observations
  67. GRB 040624, optical observations
  68. GRB 040624 - A long GRB detected with INTEGRAL
  69. GRB 030329: Rebrightening of hyperluminal ejecta.
  70. IPN Summary of SGR1806-20 Activity in 2004
  71. GRB040511: Retraction of redshift identification
  72. SGR 1806-20: no IR variability of the proposed counterparts
  73. MASTER:HETE Alert 3259 (SRG1806-20) optical observation
  74. SGR 1806-20, potential NIR counterpart
  75. GRB 040606: Optical observations
  76. MASTER: HETE Alert 3274 optical observation
  77. Activivty of SGR 1806-20
  78. IPN triangulation of an intense intermediate burst from SGR1806-20
  79. GRB 040511, very fast decay?
  80. GRB 030324: Detection and Color of Host Galaxy
  81. GRB 040511: NIR observations with REM
  82. GRB040511: Redshift identifcation
  83. GRB 040511: Optical limit
  84. GRB040511: Candidate optical/NIR afterglow
  85. IBAS GRB Alerts n.1785 to 1791
  86. GRB 040511: ROTSE-III Rapid Optical Upper Limits
  87. GRB 040511: Second Epoch Optical Observations
  88. IBAS GRB Alerts 1781-4
  89. GRB 040511: Optical observations
  90. GRB 040511: Optical Observations
  91. GRB040511: Optical Observations
  92. GRB040511: Optical Observations
  93. GRB040511 (=H3218): A Long GRB Localized by HETE WXM and SXC
  94. IBAS GRB Alert number 1774: NOT a real GRB
  95. Type Ic SN2001em (off-axis GRB jet?), optical spectrum
  96. IBAS Alerts 1771 and 1772: NOT a real GRB
  97. GRB and XRF on April 27, 2004. Detection by Konus-Wind and Helicon (Coronas-F)
  98. IPN triangulation of GRB040425 (=H3183)
  99. On Line Availability of Archival HETE Fregate Data and Lightcurves
  100. GRB040422: optical observations at Xinglong Observatory

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