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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"

19565 results found.

  1. IPN triangulation of GRB021014 (large error box)
  2. IPN triangulation of GRB021013 (two small error boxes)
  3. XRF 020903: flattening of the optical light curve.
  4. GRB021004, UBVRcIc field photometry update
  5. IPN triangulation of GRB021008 (single error box)
  6. IPN triangulation of GRB021008 (two small error boxes)
  7. GRB021004 Chandra HETG Observations
  8. GRB 021004: Optical/NIR Observations
  9. GRB 021004: Additional V-band Polarimetric Observations
  10. GRB021004: optical observation
  11. GRB 021004: Host Galaxy Star Formation Rate
  12. GRB 021004: WC wind?
  13. GRB021004: NIR and Optical observations
  14. IPN triangulation of GRB021007 (annulus)
  15. XRF 020903 spectrum
  16. GRB021004: BVRc photometry
  17. GRB 021004 redshift
  18. GRB021004 radio observation
  19. HETE fluences for GRB021004
  20. GRB 021004: Optical Photometry at 2.5 Days
  21. GRB 021004: polarimetric observations
  22. GRB 021004: V-band Polarimetric Observations
  23. GRB021004: Update Bisei photometric data
  24. GRB 021004: Optical Decay
  25. GRB 021004 radio observation
  26. GRB 021004: Optical Photometry at 1.5 Days
  27. GRB021004, BVRcIc field photometry
  28. GRB021004: Optical Spectroscopy
  29. GRB 021004 radio search
  30. XRF020903, BVRI field photometry
  31. GRB021004(=H2380): A Long GRB Localized by HETE in Near-Real Time
  32. XRF020903: TNG and Asiago photometry
  33. XRF 020903: Correction to GCN 1560
  34. XRF 020903: VRI observations
  35. XRF 020903: R band observations
  36. IPN triangulation of GRB020923 (two error boxes)
  37. IPN triangulation of GRB020914 - clarification and additional information
  38. GRB 020305: HST/STIS observations
  39. XRF 020903: optical observation at Kyoto
  40. GRB020322 : HST/STIS observations
  41. XRF 020903: Optical observations
  42. IPN triangulation of GRB020904
  43. INTEGRAL GRBs added to GCN
  44. SGR1900+14 burst localized by HETE
  45. GRB020812: negative optical observations
  46. GRB 020812: optical observation at Kyoto University
  47. Second epoch K band imaging of GRB 020819
  48. GRB 020813 : HST observations
  49. GRB 020812: early time optical observation at Ouda Station
  50. GRB020813: Magellan BVRI Photometry
  51. GRB 020819: Optical observations
  52. GRB020819(=H2275): A Long Burst Localized by the HETE WXM and SXC
  53. GRB020813: optical and NIR observations
  54. GRB020813: Fading X-ray Afterglow Observed with Chandra
  55. GRB020813, UBVRI field calibration
  56. Polarimetry of GRB020813: evidence for variability
  57. GRB020812: optical observations
  58. GRB020813: High-Resolution Optical Observations
  59. GRB020812: optical observations
  60. GRB020813, optical observations
  61. GRB020813, astrometric position
  62. GRB020813(=H2262): A Long, Bright Burst Localized by HETE in Near-Real Time
  63. GRB 020812 optical observation
  64. GRB020812(=H2257): A Long Burst Localized by HETE in Near-Real Time
  65. GRB020801: Imaging of Suggested OT Counterpart at the Magellan
  66. HST Imaging of the Host of GRB 011121
  67. GRB020801, optical afterglow candidate
  68. GRB020331: Late-time Optical Light Curve (re-submission)
  69. GRB020331: Late-time Optical Light Curve
  70. IPN triangulation of GRB020714
  71. IPN triangulation of GRB150702
  72. GRB 020410: Discovery of Probable OT by HST
  73. IPN triangulation of GRB020708
  74. GRB 020705: Optical observations
  75. GRB 020625, optical observations
  76. GRB 020625: Optical observations
  77. GRB 020531: optical photometry of Chandra sources
  78. GRB020625 (=H2081): A Long Burst Localized by HETE
  79. The Probable Host Galaxy of GRB/XRF 020427
  80. GRB/XRF 020427, detection of an underlying system with the VLT
  81. Gemini IR Detection of AXP 1E 2259+586 Post-Burst
  82. AXP 1E2259+586 optical observations
  83. Fading Optical Source in the Field of GRB020531
  84. GRB 020531, INT+WFC deep optical upper limits
  85. SGR-like Bursts from the AXP 1E 2259+586
  86. GRB020405: polarimetric observations
  87. GRB 020531, simultaneous optical observations
  88. GRB 020604, optical observations
  89. GRB020531: Second epoch Chandra observations
  90. GRB020604, optical observations
  91. GRB020604, BVRcIc field photometry
  92. GRB020603, BVRcIc field observations
  93. GRB020531, BVRcIc field photometry
  94. IPN triangulation of GRB020604
  95. GRB020531 Optical Observations
  96. GRB020531: Observations with the Chandra X-ray Observatory
  97. GRB020531, optical observations
  98. GRB020531: optical observations
  99. GRB020531(=H2042): Optical Observations
  100. GRB020531(=H2042): Optical Observations

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