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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"

3115 results found.

  1. GRB051028: Swift-XRT refined analysis
  2. GRB051105A: Swift/UVOT Observations
  3. GRB051103:_MASTER_optical_observations
  4. GRB051028: WHT optical candidate
  5. GRB051028: Swift XRT Position
  6. SGR 1806-20: continued moderate activity seen with INTEGRAL
  7. GRB051012: Swift-XRT analysis
  8. GRB 051021B: Refined analysis of the Swift-BAT burst
  9. GRB 051021: SOAR NIR Observations
  10. Swift-BAT triggered on a posible CR Shower or possible GRB
  11. GRB 051012: Swift-BAT detection of burst yesterday
  12. GRB 050922B: optical limit
  13. GRB 050906: Possible X-ray Counterpart
  14. GRB 050906: MARGE Optical Limits
  15. GRB 050824: MDM Observations
  16. GRB050824: First 2 hours of power low optical decay?
  17. GRB050824: MASTER final analysis of the OT observations
  18. GRB050822: Swift/UVOT upper limits
  19. GRB050813: Maidanak I-band observations
  20. GRB 050822: Swift detection of a long burst
  21. GRB050807(=H3889): An X-Ray Rich GRB Localized by HETE
  22. GRB050803: CrAO optical observations, no OT candidate
  23. GRB 050805b: OHP optical limits
  24. GRB 050803: Magellan Observations
  25. GRB 050803: early Swift XRT analysis results
  26. GRB 050730: OHP optical observations
  27. GRB 050802: early Swift XRT analysis results
  28. GRB 050802: Swift/UVOT observations
  29. GRB 050802: XRT position
  30. Swift-BAT trigger 147918 is not a real GRB
  31. Swift BAT Trigger 146986 is SWIFT J1753.5-0127
  32. GRB050716, optical observation
  33. GRB 050713, R-band observations at NOT
  34. GRB050607: prompt REM observations
  35. GRB050525: Super-LOTIS observations
  36. GRB 050525: Optical observation
  37. XRF050522: NIR observations of XRT candidate
  38. XRF 050522: Swift XRT refined analysis
  39. GRB050502b: Early Observation
  40. GRB 050505, early TAROT observation
  41. GRB050509a: Swift UVOT observations
  42. GRB 050509a: Swift XRT Position
  43. Swift Detection of the Burst GRB050509
  44. GRB 050505: Keck I-band Magnitude
  45. GRB 050505: early time observations
  46. GRB (?) 050504: IR Observations, Intriguing Source
  47. GRB050326: optical limit
  48. Swift Detection of GRB 050319
  49. RXTE Observations of GRB050318
  50. GRB050309: CONCAM pre-trigger and trigger coincident optical
  51. GRB050215b: Faulkes North and SDSS limits on UKIRT candidate
  52. GRB 050219b: Swift XRT Position
  53. GRB050215b: Swift UVOT Detection of Afterglow Emission
  54. GRB 050215b: XRT confirmation of IR afterglow candidate
  55. GRB 050215B: candidate afterglow
  56. GRB 050215B: UKIRT K-band imaging
  57. GRB 050215b: Swift XRT Observations
  58. GRB050126: MASTER optical limit for KECK OT
  59. GRB050126: MASTER optical observations
  60. GRB050117: Palomar WIRC Ks-band observations
  61. GRB 041217: Optical observations
  62. GRB041226: ROTSE-III Optical Observations
  63. GRB041218: Continued P60 Optical Observations
  64. GRB 041218: Optical observations
  65. GRB041211,optical observation
  66. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  67. SGR 1806-20 still active
  68. GRB040924,optical observation
  69. IBAS GRB Alerts 1978-1980
  70. GRB040903 - A XRF?
  71. XRF040812: GMRT observations
  72. GRB 040812: Optical counterparts of CXO sources
  73. GRB 040812: Keck and LCO optical observations
  74. GRB 040812: Keck and LCO observations
  75. GRB040624: optical monitoring at TNG
  76. XRF040701: Second-Epoch Chandra Observations
  77. XRF040701: VLA Observations
  78. XRF040701: First-Epoch Chandra Observations
  79. IPN Summary of SGR1806-20 Activity in 2004
  80. MASTER: HETE Alert 3274 optical observation
  81. GRB040511: Candidate optical/NIR afterglow
  82. GRB 040319 (=H3128): An X-Ray-Rich GRB Localized by the HETE-2 WXM and SXC
  83. GRB 040228 (=H3066?,=H3067?): A Long GRB Localized by the HETE-2 WXM
  84. GRB031220: 2nd Chandra observation and X-ray afterglow candidate
  85. GRB040106: refined X-ray transient position
  86. GRB040106, Radio Observations
  87. GRB040106, likely optical afterglow
  88. GRB 040106: Optical observations
  89. XMM-Newton observation of GRB040106
  90. GRB 040106 : Planned XMM-Newton observation
  91. GRB 040106 : a long GRB detected with INTEGRAL
  92. GRB031220: Palomar Observations
  93. GRB 031203: IR NTTobservations do not confirm REM detection
  94. SN 2003jd (SN/GRB?) -- X-ray Observations
  95. IPN triangulation of GRB031016 (two large error boxes)
  96. XRF030824 (=H2821): An X-Ray Flash Localized by the HETE WXM
  97. IPN triangulation of GRB030921 (large error box)
  98. IPN triangulation of GRB030806 (large burst; large error box)
  99. XRF030723, ROTSE-III Early Observations
  100. XRF030723, optical observations

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