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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"

27395 results found.

  1. GRB 040812: Second epoch CXO Observations
  2. GRB040823,optical observation
  3. XRF040812: GMRT observations
  4. XRF 040812: optical observation at VLT
  5. GRB 040812: Optical counterparts of CXO sources
  6. XRF040812: possible afterglow
  7. CXO observation of GRB 040812
  8. GRB 040812: radio observations
  9. GRB040812, optical/IR observations
  10. GRB 040812: a long GRB detected by INTEGRAL
  11. XRF040701: Optical Observations at ESO
  12. GRB 040730, infrared observations
  13. GRB 040730: a long GRB detected with INTEGRAL
  14. Ongoing activity of SGR 1806-20
  15. GRB040624: optical monitoring at TNG
  16. XRF 040701 - optical observations of the decaying Chandra source
  17. XRF040701: Second-Epoch Chandra Observations
  18. XRF040701: VLA Observations
  19. XRF040701: First-Epoch Chandra Observations
  20. GRB040624, optical observations
  21. GRB040706:observation at University of Miyazaki
  22. Optical Observations of GRB040624
  23. GRB 040624: optical observations at TNG and VLT
  24. MASTER: GRB 040624 optical observation after 0,48d
  25. GRB 040624, optical observations
  26. GRB 040624 - A long GRB detected with INTEGRAL
  27. GRB 030329: Rebrightening of hyperluminal ejecta.
  28. IPN Summary of SGR1806-20 Activity in 2004
  29. SGR 1806-20: no IR variability of the proposed counterparts
  30. MASTER:HETE Alert 3259 (SRG1806-20) optical observation
  31. SGR 1806-20, potential NIR counterpart
  32. GRB 040606: Optical observations
  33. MASTER: HETE Alert 3274 optical observation
  34. Activivty of SGR 1806-20
  35. GRB 040511, very fast decay?
  36. GRB 030324: Detection and Color of Host Galaxy
  37. GRB 040511: NIR observations with REM
  38. GRB040511: Candidate optical/NIR afterglow
  39. GRB 040511: ROTSE-III Rapid Optical Upper Limits
  40. GRB 040511: Second Epoch Optical Observations
  41. GRB 040511: Optical observations
  42. GRB 040511: Optical Observations
  43. GRB040511: Optical Observations
  44. GRB040511: Optical Observations
  45. Type Ic SN2001em (off-axis GRB jet?), optical spectrum
  46. GRB 040423 (=H3175): A Long GRB Localized by HETE
  47. GRB040422 : I-band follow-up observation at Lulin Observatory
  48. GRB 040422: ROTSE-IIIb Prompt Optical Limits
  49. GRB040422, BVRcIc field calibration
  50. GRB 040422,optical observation
  51. GRB 040422: a long GRB detected with INTEGRAL
  52. GRB 040403, deep optical observations
  53. MASTER: HETE Alert 3163, 3167 technical optical observation
  54. HETE/IPN localization of GRB040403A (=H3143, a long burst) and GRB040403B(=H3144, a short/hard burst)
  55. GRB 040403: Optical observations
  56. GRB 040403: a long GRB detected with INTEGRAL
  57. GRB040323: NIR Observations and Variable Object
  58. GRB 040319 (=H3128): An X-Ray-Rich GRB Localized by the HETE-2 WXM and SXC
  59. GRB 040323, a dark GRB ?
  60. GRB 040323: a long GRB detected with INTEGRAL
  61. GRB040223: Deep NIR NTT data re-analysis
  62. GRB 040223: XMM-Newton results
  63. GRB040223, improved XMM position
  64. GRB 031203, possible supernova
  65. MASTER: RXTE GRB040308 optical observation
  66. IBAS results on a burst from SGR1806-20
  67. INTEGRAL detection of activity from SGR1806-20
  68. RXTE GRB040229 optical observation: no candidate
  69. GRB 040228 Optical observations
  70. GRB040228 : KISO optical follow-up observation
  71. GRB 040223: Deep NIR NTT observations
  72. GRB 040223 : Optical observation (non-detection)
  73. XMM-Newton Images of GRB 040223
  74. GRB 040223, VLA observations
  75. GRB 040223: REM IJK Observations
  76. GRB 040223 XMM-Newton observation ...
  77. GRB 031203 XMM-Newton observation
  78. GRB 040223: further offline analysis
  79. GRB031111, optical observations
  80. GRB031220: 2nd Chandra observation and X-ray afterglow candidate
  81. GRB031203: Chandra Observations
  82. GRB040106: refined X-ray transient position
  83. SN 2003dh/GRB030329 late-time optical spectroscopy
  84. GRB 031220: Optical observations of Chandra X-ray sources
  85. XMM-Newton Images of GRB 040106
  86. GRB031220: observation at Univercity of Miyazaki
  87. XMM-Newton observation of GRB040106
  88. GRB 040106 : peak flux
  89. GRB031220(=H2976): TNG R-band Observation of the Chandra X-ray Sources
  90. GRB031220(=H2976): Observation with the Chandra X-ray Observatory
  91. GRB031220: Palomar Observations
  92. GRB 031220 : Kyoto Optical Observation
  93. GRB 031220: Subaru observation
  94. GRB 031220: Optical observation at Tokyo Tech
  95. GRB 2974 follow-up observations
  96. GRB031203, improved XMM position
  97. GRB 021203: A Normal GRB viewed far off axis?
  98. XMM-Newton Observations of GRB031203: Preliminary Images
  99. GRB 031203: Variable Radio Source
  100. GRB 031203: Magellan spectrum of possible GRB host

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