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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"
  1. IPN localization of GRB070124 (short duration, hard spectrum)
  2. GRB 070110: optical break
  3. Swift-BAT trigger 257213 is a Galactic Center transient
  4. GRB 070110: Continued Detection and Request for Ground Followup
  5. GRB 050904: Second Epoch of HST/NICMOS Observations
  6. GRB 070110: Ep,i - Eiso correlation
  7. GRB 070107: Suzaku WAM observation of the prompt emission
  8. GRB 070110: VLT R-band photometry
  9. GRB 070110 declared a "Burst of Interest" by Swift team
  10. Further Retractions of previous Swift-BAT triggers
  11. Swift-BAT Trigger 255685 is not a GRB
  12. Trigger 255685: Swift detection of a possible burst
  13. GRB 070110: VLT absorption redshift
  14. GRB 070110: UVOT Observations of a Candidate Afterglow
  15. GRB070110: Swift XRT Team refined analysis
  16. GRB 070110, Swift-BAT refined analysis
  17. GRB070107 Swift/UVOT Observations of a Fading Optical Afterglow
  18. GRB 070110: Swift detection of a burst with a possible optical afterglow
  19. IBAS Alert n. 4047: Not a GRB
  20. GRB070107: Swift/XRT refined analysis
  21. GRB 070107: Possible UVOT Afterglow
  22. GRB 070107, Swift-BAT refined analysis
  23. GRB 070107: Swift/XRT position
  24. GRB 070107: Swift detection of a burst
  25. VLA observation of GRB 061222B
  26. VLA detection of GRB 061222A
  27. GRB070103: APO SPIcam i' and z' limits
  28. GRB 061201: Nearby Galaxy Cluster Abell 995 is at z=0.0865
  29. GRB070103: KPNO 4m+FLAMINGOS J limit
  30. GRB 070103: Swift/UVOT Upper limits
  31. GRB070103: Swift XRT refined analysis
  32. GRB 070103, Swift-BAT refined analysis
  33. GRB 070103: NOT observations
  34. GRB 070103: TAROT Calern observatory optical observations
  35. GRB 070103: Swift detection of a burst
  36. Retractions of previous Swift-BAT triggers
  37. GRB061222a: optical observations
  38. erratum : SDSS Pre-burst Observations of GRB061126
  39. Konus-Wind observation of GRB 061222A
  40. GRB 061210: Swift/XRT Astrometry Correction
  41. GRB 050826: MDM Redshift
  42. GRB 061222B: TAROT La Silla observatory early optical observations
  43. GRB 061218: TAROT La Silla observatory early optical observations
  44. GRB 061222A: MITSuME Akeno optical upper limits
  45. GRB 061222A: Confirmation of Gemini Afterglow Candidate
  46. GRB 061222B: MITSuME Akeno optical upper limits
  47. GRB 061222A: Xinglong Optical Limit
  48. GRB 061222A: Gemini Afterglow Candidate
  49. GRB 061222B, Swift-BAT refined analysis
  50. GRB061222A Swift/UVOT: Upper Limits
  51. GRB 061222B: Swift/UVOT Upper limits
  52. GRB 061222B: Observation with the KANATA 1.5m telescope
  53. GRB061222B: Swift-XRT Refined Analysis
  54. GRB 061222A: Observation with the KANATA 1.5m telescope
  55. GRB 061222B: BOOTES-IR optical observations
  56. GRB 061222B: SARA upper limit
  57. GRB 061222A: Swift-XRT refined analysis
  58. GRB 061217: Magellan host galaxy redshift
  59. GRB 061222A, Swift-BAT refined analysis
  60. GRB 061222B: REM NIR/optical observations
  61. GRB 061222b: Refined redshift
  62. GRB 061222b, SMARTS optical/IR afterglow observations
  63. GRB 061222B: TAROT La Silla observatory afterglow observation
  64. GRB 061222B: TAROT La Silla observatory optical observations
  65. GRB 061222b: Magellan redshift
  66. GRB 061222B: Swift detection of a burst
  67. GRB 061222b: optical afterglow
  68. GRB 061222A: Prompt ROTSE-III Optical Limits
  69. GRB 061222: Swift detection of a burst
  70. GRB 061217: Astrometry-Corrected XRT Position
  71. GRB 061201: Magellan redshift of nearby galaxy
  72. GRB 061217: Confirmation of host candidate
  73. GRB 061217: Object ib GCN 5948 is a star
  74. GRB 061217: Extended object in the revised XRT error circle
  75. GRB 061217, Candidate host galaxy
  76. GRB 061217 - Swift/XRT position correction
  77. GRB 061210: Possible Host Galaxy (S2-G2) Keck Spectrum
  78. GRB 061201: Correction to GCN 5944
  79. GRB 061201: Magellan Redshift of nearby Abell cluster
  80. GRB 061218: TAROT La Silla observatory optical observations
  81. GRB 061217: TAROT Calern observatory optical observations
  82. GRB 061218: TORTOREM optical upper limits
  83. GRB 061218, Swift-BAT refined analysis
  84. GRB061217: VLT NIR observations
  85. GRB 061218, SMARTS optical/IR observations
  86. GRB 061218: REM prompt observations
  87. Swift triggers (#251863) on a possible burst
  88. GRB 061217, SMARTS optical observations
  89. GRB061217: Swift/UVOT refined analysis.
  90. GRB 061217: optical observations at Calar Alto
  91. GRB061217 - Swift/XRT refined analysis
  92. GRB 061217, Further Swift-BAT refined analysis of the short hard burst
  93. GRB 061217, Swift-BAT refined analysis
  94. GRB 061217: Magellan Observations
  95. GRB 061217: REM prompt observations
  96. GRB 061217: ROTSE-III Optical Limits
  97. GRB 061217: Swift detection of a short hard burst
  98. GRB 061210: MDM Follow-up Observation
  99. GRB061210: Swift/UVOT observations
  100. Swift-BAT Trigger 250908 is a Cosmic Ray Shower event

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