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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"

32490 results found.

  1. GRB 021211: early break in light curve
  2. GRB021211, BVRI field photometry
  3. GRB021211: Optical observations in CrAO
  4. GRB 021211, IR observations
  5. GRB 021211, optical observations
  6. GRB 021211: Optical Observations
  7. GRB021211: Kiso Observations
  8. GRB 021201, optical observations
  9. GRB 021211: Radio Observations
  10. GRB021211: Optical observations
  11. GRB 021201 (short/hard), NOT observations
  12. SUB-MM SEARCH FOR GRB 021211
  13. Chandra observation of the IPN error box of GRB021201 (short/hard)
  14. GRB 021211, R- and I-band observations
  15. GRB021211 - Upper limits from recent and historical observations
  16. GRB021211, OT at 108 s
  17. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  18. HETE 2493: Optical observations
  19. GRB 021125: Radio Observations
  20. IPN triangulation of GRB021206 (small error box)
  21. GRB 021104, GRB 021112 and GRB 021113 - Milagro GeV/TeV Observations
  22. GRB021201, BVRcIc field photometry
  23. GRB 021201, Radio Observations
  24. GRB 021201: Optical Observations
  25. GRB 021201: BOOTES simultaneous optical observations
  26. GRB021004, late time optical observations
  27. GRB021004 Chandra Observation
  28. GRB021125 refined position
  29. IPN triangulation of GRB021125B (two large error boxes)
  30. IPN triangulation of GRB021119 (large error box)
  31. Improved IPN error box for GRB021125
  32. IPN BURST POSITION
  33. IPN confirmation of the reactivation of SGR1900+14
  34. GRB021113, SPI ACS observation
  35. GRB 021112: Afterglow or Variable Star?
  36. GRB021113: optical observations at Bisei
  37. GRB 021113: Evidence for a Dark Optical Afterglow
  38. GRB 021112: Variable Source in R-band search
  39. GRB021112: Optical Observations
  40. IPN triangulation of GRB021109 (portion of annulus)
  41. IPN triangulation of GRB021113 (=H2449; annulus)
  42. IPN triangulation of GRB021108 (CORRECTION; TWO LARGE ERROR BOXES)
  43. GRB 021113: Optical Observations
  44. GRB 021113: Optical Observations
  45. GRB021113 (=H2449): A Long GRB Localized by HETE
  46. GRB 021112: Optical Observations
  47. GRB 021112: R-band search
  48. IPN triangulation of GRB021108 (large error box)
  49. GRB021112 (=H2448): A Long GRB Localized by HETE
  50. GRB 021016: Optical Observations
  51. GRB021004: Near infrared spectroscopy
  52. GRB021104(=H2434): A Long, X-Ray-Rich GRB Localized by HETE
  53. Spectropolarimetry of GRB021004
  54. GRB021104: optical observations
  55. GRB021104: Candidate present in DSS
  56. IPN triangulation of a burst from SGR1900+14 on November 01, 2002
  57. IPN triangulation of a burst from SGR1900+14 on October 29 2002
  58. IPN triangulation of GRB021025 (portion of annulus)
  59. IPN triangulation of GRB021027 (single large error box)
  60. GRB021004, late-time optical observations
  61. IPN triangulation of GRB021027 (two large error boxes)
  62. GRB 021023: Infrared Imaging
  63. GRB 021023: Curious K-band Source(s) Just Outside of IPN Localization
  64. IPN triangulation of SGR1900+14, October 22 2002
  65. GRB 021004: optical observations
  66. GRB021004: Optical Observations
  67. GRB 020813; likely host galaxy.
  68. IPN triangulation of GRB021020 (smaller error box)
  69. GRB021021(=XRF 021021): An X-ray Flash Localized by HETE
  70. GRB 021008, radio observations
  71. GRB 021016, optical observations
  72. GRB 021004: VRI observations at TNG: possible break
  73. GRB021016, optical observations
  74. GRB 021008, optical observations
  75. GRB021016(=H2397): A Long GRB Localized by HETE
  76. IPN triangulation of GRB021016 (area corrected)
  77. IPN triangulation of GRB021016 (small error box)
  78. GRB021004: Optical Observations
  79. IPN triangulation of GRB021013 (single error box)
  80. GRB 021004: optical spectroscopy on Oct 11
  81. IPN triangulation of GRB021013 (two small error boxes)
  82. GRB021004: High-resolution optical spectroscopy
  83. XRF 020903: flattening of the optical light curve.
  84. GRB021004, UBVRcIc field photometry update
  85. IPN triangulation of GRB021008 (single error box)
  86. GRB021004: Optical Observations
  87. GRB 021004 submm observations
  88. IPN triangulation of GRB021008 (two small error boxes)
  89. GRB 021004: Optical/NIR Observations
  90. GRB 021004: Additional V-band Polarimetric Observations
  91. GRB021004: optical observation
  92. GRB 021004: Host Galaxy Star Formation Rate
  93. GRB 021004 submm observations
  94. GRB 021004: WC wind?
  95. GRB021004: NIR and Optical observations
  96. GRB 021004: Optical measurement at OHP
  97. GRB 021004: Optical observations, AUDE network
  98. GRB 021004 - VLA Radio Observations
  99. GRB 021004 - Unusual Radio-to-Submm Spectrum
  100. XRF 020903 spectrum

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