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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"

2797 results found.

  1. IPN detection of continued activity from SGR1806-20
  2. XRF 030824: observations at CFHT
  3. XRF030823 (=H2818): An X-Ray Flash Localized by the HETE WXM and SXC
  4. GRB030922 triangulation (annulus)
  5. GRB030913: OT's limit by MASTER
  6. GRB 030913, optical candidate
  7. IPN triangulation of GRB030916 (possible short/hard GRB; large error box)
  8. GRB030913 (=H2849): TAROT Observations
  9. GRB030913 (=H2849): A GRB Possibly Localized by HETE
  10. IPN triangulation of GRB030908 (annulus)
  11. IPN detection of continued activity from SGR1806-20
  12. SGR 1808-20 (=H2802): A Possible new SGR
  13. XRF030723: Re-analysis of ROTSE-III early images
  14. GRB030725, possible optical transient
  15. RXTE PCA Observations of SGR1806-20 Region
  16. IPN triangulation of GRB030711 (annulus, =SGR0525-66?)
  17. MASTER: optical observation GRB030601
  18. GRB 030329: Correction to GCN 2254
  19. GRB 030329: Optical Observations
  20. GRB 030329/SN 2003dh: Possible increase in brightness
  21. GRB 021004: HST observations
  22. IPN triangulation of GRB030518B (annulus)
  23. GRB030429: RTT150 optical observations, a possible host galaxy
  24. GRB 030501: TAROT possible candidate counterpart
  25. GRB030429, possible optical counterpart
  26. SNeIa AS THE POSSIBLE PROGENITORS OF SHORT-DURATION GRBs.
  27. Optical Observations of GRB 030418 with Magellan
  28. IPN triangulation of GRB030422C (annulus)
  29. GRB 030329: SARA Optical Observations
  30. OT GRB 030329: early spectrum
  31. IPN triangulation of GRB030410 (annulus)
  32. GRB 030329, color evolution
  33. GRB030329: Optical observcations
  34. GRB 030329: possible color change
  35. OT GRB light curves and SN predictions
  36. GRB 030329: fitting parameters and re-brightening
  37. GRB 030329: optical observations
  38. 030331 NOT A GRB
  39. GRB030329: ROTSE network observes steepening of decay curve
  40. GRB 030329: optical observations
  41. GRB 030329 follow-up
  42. Possible GRB030323 localized by INTEGRAL
  43. IPN triangulation of GRB030325 (final analysis)
  44. IPN triangulation of GRB030325 (two small error boxes)
  45. GRB030323, ROTSE-III detection of possible optical counterpart
  46. GRB030324, BVRcIc field photometry
  47. GRB030323, possible optical counterpart
  48. GRB030323, BVRcIc field calibration
  49. Possible GRB 030320 localized by INTEGRAL
  50. IPN triangulation of GRB030306 (two small error boxes)
  51. GRB 030226: Ic Observations
  52. GRB 030227 optical afterglow
  53. 030302: NOT A GRB
  54. 030228: NOT A GRB
  55. GRB 030227, possible optical counterpart of XMM-Newton source
  56. GRB030227 - faint tentative OT candidate
  57. Possible break in the GRB 030226 light curve
  58. GRB 030217: Optical Observations at 4, 5, and 6 Days
  59. IPN triangulation of GRB030206 (annulus)
  60. GRB030131: Candidate Optical Afterglow
  61. IPN triangulation of GRB030117 (two large error boxes)
  62. Publicizing GRB Discoveries - A Message from NASA HQ
  63. GRB 030115 : Possible IR counterpart
  64. GRB030115: TAROT optical observations
  65. Possible GRB030113 seen by SPI ACS
  66. Probable GRB030112B seen by SPI ACS
  67. Possible GRB030111 seen by SPI ACS
  68. Possible GRB030110b seen by SPI ACS
  69. Possible GRB 030110 seen by SPI ACS
  70. Possible GRB 20030109 seen by SPI ACS
  71. Possible GRB20030107 seen by SPI-ACS
  72. Possible GRB 20030105 seen by SPI ACS
  73. IPN triangulation of GRB030101 (two large error boxes)
  74. GRB 021211, optical observations
  75. IPN detection of renewed activity from SGR1806-20
  76. IPN triangulation of GRB021125B (two large error boxes)
  77. IPN triangulation of GRB021119 (large error box)
  78. GRB021125 : A long GRB localized by INTEGRAL
  79. IPN detection of possible reactivation of SGR1900+14
  80. GRB021104: optical observations
  81. GRB021104: possible optical afterglow
  82. IPN triangulation of GRB021020
  83. GRB 021004: VRI observations at TNG: possible break
  84. IPN triangulation of GRB021013 (two small error boxes)
  85. IPN triangulation of GRB021013 (annulus)
  86. XRF 020903: flattening of the optical light curve.
  87. GRB021004, UBVRcIc field photometry update
  88. IPN triangulation of GRB021007 (annulus)
  89. GRB 021004: polarimetric observations
  90. GRB 021004: Optical Observations
  91. XRF020903: TNG and Asiago photometry
  92. XRF 020903: R band observations
  93. XRF 020903: Archival Optical Images
  94. IPN triangulation of GRB020926 (two large error boxes)
  95. IPN triangulation of GRB020923 (two error boxes)
  96. IPN annulus for GRB020923
  97. IPN triangulation of GRB020914B
  98. Improved IPN position for GRB020918 (two large error boxes)
  99. IPN annulus for GRB020914B
  100. IPN triangulation of GRB020911 (2 large error boxes)

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