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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"

41624 results found.

  1. GRB 040812: Optical counterparts of CXO sources
  2. XRF040812: possible afterglow
  3. CXO observation of GRB 040812
  4. Bursting activity from SGR 1806-20 detected with IBAS
  5. IPN/HETE localizations of GRB040810 (=H3489)
  6. GRB 040812: Keck and LCO optical observations
  7. GRB 040812: Keck and LCO observations
  8. GRB 040812: radio observations
  9. GRB040812, optical/IR observations
  10. GRB 040812: a long GRB detected by INTEGRAL
  11. GRB 040810: Optical observations of a limited region
  12. XRF040701: Optical Observations at ESO
  13. GRB 040730, infrared observations
  14. GRB 040730: Optical observations
  15. GRB 040730: a long GRB detected with INTEGRAL
  16. GRB040624: optical monitoring at TNG
  17. XRF 040701 - optical observations of the decaying Chandra source
  18. XRF040701: Second-Epoch Chandra Observations
  19. Cancellation of IBAS/INTEGRAL GRB alerts
  20. XRF040701: VLA Observations
  21. XRF040701: Magellan Spectroscopy of Chandra Source #2 Associated Galaxy
  22. XRF040701: First-Epoch Chandra Observations
  23. GRB040709 J,H-band observations
  24. GRB040624, optical observations
  25. GRB040706:observation at University of Miyazaki
  26. XRF 040701, optical observations
  27. XRF040701 (=U11548): a bright XRF detected by HETE
  28. GRB 040624: optical observations
  29. Optical Observations of GRB040624
  30. GRB 040624: optical observations at TNG and VLT
  31. MASTER: GRB 040624 optical observation after 0,48d
  32. GRB 040624: R-band observations
  33. GRB 040624, optical observations
  34. GRB 040624 - A long GRB detected with INTEGRAL
  35. GRB 030329: Rebrightening of hyperluminal ejecta.
  36. IPN Summary of SGR1806-20 Activity in 2004
  37. GRB040511: Retraction of redshift identification
  38. SGR 1806-20: no IR variability of the proposed counterparts
  39. SGR 1806-20, potential NIR counterpart
  40. GRB 040606: Optical observations
  41. Activivty of SGR 1806-20
  42. GRB 040511, very fast decay?
  43. GRB 030324: Detection and Color of Host Galaxy
  44. GRB 040511: NIR observations with REM
  45. GRB040511: Redshift identifcation
  46. GRB 040511: Optical limit
  47. GRB040511: Candidate optical/NIR afterglow
  48. GRB 040511: ROTSE-III Rapid Optical Upper Limits
  49. GRB 040511: Second Epoch Optical Observations
  50. GRB 040511: Optical observations
  51. GRB 040511: Optical Observations
  52. GRB040511: Optical Observations
  53. GRB040511: Optical Observations
  54. GRB040511 (=H3218): A Long GRB Localized by HETE WXM and SXC
  55. Type Ic SN2001em (off-axis GRB jet?), optical spectrum
  56. GRB and XRF on April 27, 2004. Detection by Konus-Wind and Helicon (Coronas-F)
  57. On Line Availability of Archival HETE Fregate Data and Lightcurves
  58. GRB040422: optical observations at Xinglong Observatory
  59. GRB040422: optical observations at CrAO
  60. GRB 040423 (=H3175): A Long GRB Localized by HETE
  61. GRB040422, optical observations at Loiano
  62. GRB040422 : I-band follow-up observation at Lulin Observatory
  63. GRB 040422: ROTSE-IIIb Prompt Optical Limits
  64. GRB040422, BVRcIc field calibration
  65. GRB 040422,optical observation
  66. GRB040422: optical and NIR observations at the VLT
  67. GRB 040422: a long GRB detected with INTEGRAL
  68. GRB 040403, deep optical observations
  69. INTEGRAL-SPI/ACS GRB data: timing correction
  70. HETE/IPN localization of GRB040403A (=H3143, a long burst) and GRB040403B(=H3144, a short/hard burst)
  71. GRB 040403: Optical Observations
  72. GRB 040403 Optical Observations
  73. GRB 040403: Optical observations
  74. GRB 040403: optical observations
  75. GRB 040403: Optical Observations
  76. GRB 040403: a long GRB detected with INTEGRAL
  77. Summary of recent bursts from SGR 1806-20 detected by INTEGRAL
  78. GRB040323: NIR Observations and Variable Object
  79. GRB 040323, a dark GRB ?
  80. GRB 040323: a long GRB detected with INTEGRAL
  81. GRB040223: Deep NIR NTT data re-analysis
  82. GRB 040223: XMM-Newton results
  83. GRB 031203: spectoscopic evidence for a 1998bw-like SN
  84. GRB 031203, possible supernova
  85. MASTER: RXTE GRB040308 optical observation
  86. IBAS results on a burst from SGR1806-20
  87. INTEGRAL detection of activity from SGR1806-20
  88. RXTE GRB040229 optical observation: no candidate
  89. GRB 040228 Optical observations
  90. IPN triangulation of GRB040228 (H3066, H3067)
  91. GRB040228 : KISO optical follow-up observation
  92. GRB 040228 (=H3066?,=H3067?): A Long GRB Localized by the HETE-2 WXM
  93. GRB 040223: Deep NIR NTT observations
  94. GRB 040223 : Optical observation (non-detection)
  95. XMM-Newton Images of GRB 040223
  96. GRB 040223, VLA observations
  97. GRB 040223: REM IJK Observations
  98. GRB 040223 XMM-Newton observation ...
  99. GRB 031203 XMM-Newton observation
  100. GRB 040223: a long GRB detected with INTEGRAL

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