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

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