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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"

27392 results found.

  1. XRF 040812: optical observation at VLT
  2. GRB 040812: Optical counterparts of CXO sources
  3. XRF040812: possible afterglow
  4. CXO observation of GRB 040812
  5. GRB 040812: radio observations
  6. GRB040812, optical/IR observations
  7. GRB 040812: a long GRB detected by INTEGRAL
  8. XRF040701: Optical Observations at ESO
  9. GRB 040730, infrared observations
  10. GRB 040730: a long GRB detected with INTEGRAL
  11. Ongoing activity of SGR 1806-20
  12. GRB040624: optical monitoring at TNG
  13. XRF 040701 - optical observations of the decaying Chandra source
  14. XRF040701: Second-Epoch Chandra Observations
  15. XRF040701: VLA Observations
  16. XRF040701: First-Epoch Chandra Observations
  17. GRB040624, optical observations
  18. GRB040706:observation at University of Miyazaki
  19. Optical Observations of GRB040624
  20. GRB 040624: optical observations at TNG and VLT
  21. MASTER: GRB 040624 optical observation after 0,48d
  22. GRB 040624, optical observations
  23. GRB 040624 - A long GRB detected with INTEGRAL
  24. GRB 030329: Rebrightening of hyperluminal ejecta.
  25. IPN Summary of SGR1806-20 Activity in 2004
  26. SGR 1806-20: no IR variability of the proposed counterparts
  27. MASTER:HETE Alert 3259 (SRG1806-20) optical observation
  28. SGR 1806-20, potential NIR counterpart
  29. GRB 040606: Optical observations
  30. MASTER: HETE Alert 3274 optical observation
  31. Activivty of SGR 1806-20
  32. GRB 040511, very fast decay?
  33. GRB 030324: Detection and Color of Host Galaxy
  34. GRB 040511: NIR observations with REM
  35. GRB040511: Candidate optical/NIR afterglow
  36. GRB 040511: ROTSE-III Rapid Optical Upper Limits
  37. GRB 040511: Second Epoch Optical Observations
  38. GRB 040511: Optical observations
  39. GRB 040511: Optical Observations
  40. GRB040511: Optical Observations
  41. GRB040511: Optical Observations
  42. Type Ic SN2001em (off-axis GRB jet?), optical spectrum
  43. GRB 040423 (=H3175): A Long GRB Localized by HETE
  44. GRB040422 : I-band follow-up observation at Lulin Observatory
  45. GRB 040422: ROTSE-IIIb Prompt Optical Limits
  46. GRB040422, BVRcIc field calibration
  47. GRB 040422,optical observation
  48. GRB 040422: a long GRB detected with INTEGRAL
  49. GRB 040403, deep optical observations
  50. MASTER: HETE Alert 3163, 3167 technical optical observation
  51. HETE/IPN localization of GRB040403A (=H3143, a long burst) and GRB040403B(=H3144, a short/hard burst)
  52. GRB 040403: Optical observations
  53. GRB 040403: a long GRB detected with INTEGRAL
  54. GRB040323: NIR Observations and Variable Object
  55. GRB 040319 (=H3128): An X-Ray-Rich GRB Localized by the HETE-2 WXM and SXC
  56. GRB 040323, a dark GRB ?
  57. GRB 040323: a long GRB detected with INTEGRAL
  58. GRB040223: Deep NIR NTT data re-analysis
  59. GRB 040223: XMM-Newton results
  60. GRB040223, improved XMM position
  61. GRB 031203, possible supernova
  62. MASTER: RXTE GRB040308 optical observation
  63. IBAS results on a burst from SGR1806-20
  64. INTEGRAL detection of activity from SGR1806-20
  65. RXTE GRB040229 optical observation: no candidate
  66. GRB 040228 Optical observations
  67. GRB040228 : KISO optical follow-up observation
  68. GRB 040223: Deep NIR NTT observations
  69. GRB 040223 : Optical observation (non-detection)
  70. XMM-Newton Images of GRB 040223
  71. GRB 040223, VLA observations
  72. GRB 040223: REM IJK Observations
  73. GRB 040223 XMM-Newton observation ...
  74. GRB 031203 XMM-Newton observation
  75. GRB 040223: further offline analysis
  76. GRB031111, optical observations
  77. GRB031220: 2nd Chandra observation and X-ray afterglow candidate
  78. GRB031203: Chandra Observations
  79. GRB040106: refined X-ray transient position
  80. SN 2003dh/GRB030329 late-time optical spectroscopy
  81. GRB 031220: Optical observations of Chandra X-ray sources
  82. XMM-Newton Images of GRB 040106
  83. GRB031220: observation at Univercity of Miyazaki
  84. XMM-Newton observation of GRB040106
  85. GRB 040106 : peak flux
  86. GRB031220(=H2976): TNG R-band Observation of the Chandra X-ray Sources
  87. GRB031220(=H2976): Observation with the Chandra X-ray Observatory
  88. GRB031220: Palomar Observations
  89. GRB 031220 : Kyoto Optical Observation
  90. GRB 031220: Subaru observation
  91. GRB 031220: Optical observation at Tokyo Tech
  92. GRB 2974 follow-up observations
  93. GRB031203, improved XMM position
  94. GRB 021203: A Normal GRB viewed far off axis?
  95. XMM-Newton Observations of GRB031203: Preliminary Images
  96. GRB 031203: Variable Radio Source
  97. GRB 031203: Magellan spectrum of possible GRB host
  98. GRB 031203: Optical/IR Astrometry
  99. GRB031203: ROSAT upper limits suggest XMM-S1 source as the transient
  100. XMM-Newton Observation of GRB031203

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