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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. GRB070124: Swift-XRT Observation
  2. Possible GRB 070126: Swift/UVOT Upper Limit
  3. GRB 070125: UVOT Observations of a Fading Optical Afterglow
  4. GRB 070125: Xinglong TNT optical observations
  5. GRB 070125: Continued P60 Observations
  6. GRB 070125: pseudo-z~1.5 from spectral parameters of the prompt emission
  7. GRB 070125: Keck/LRIS Spectroscopy -- Evidence for a very low redshift
  8. GRB 070125: Lick 3m Spectroscopy
  9. GRB070125: Swift-XRT Refined Analysis
  10. GRB 070125: SARA detection in R
  11. GRB 070125: P60 Optical Afterglow Candidate
  12. GRB 070126?: Swift detection of a possible burst
  13. GRB070125 redshift request
  14. RHESSI Spectrum of GRB070125
  15. IPN-BAT localization of GRB070125 (very long duration, intense)
  16. Konus-Wind observation of short hard GRB 070124
  17. IPN localization of GRB070124 (short duration, hard spectrum)
  18. GRB 070110: optical break
  19. Swift-BAT trigger 257213 is a Galactic Center transient
  20. GRB 070110: Continued Detection and Request for Ground Followup
  21. GRB 050904: Second Epoch of HST/NICMOS Observations
  22. GRB 070110: Ep,i - Eiso correlation
  23. GRB 070107: Suzaku WAM observation of the prompt emission
  24. GRB 070110: VLT R-band photometry
  25. GRB 070110 declared a "Burst of Interest" by Swift team
  26. Further Retractions of previous Swift-BAT triggers
  27. Swift-BAT Trigger 255685 is not a GRB
  28. Trigger 255685: Swift detection of a possible burst
  29. GRB 070110: VLT absorption redshift
  30. GRB 070110: UVOT Observations of a Candidate Afterglow
  31. GRB070110: Swift XRT Team refined analysis
  32. GRB 070110, Swift-BAT refined analysis
  33. GRB070107 Swift/UVOT Observations of a Fading Optical Afterglow
  34. GRB 070110: Swift detection of a burst with a possible optical afterglow
  35. IBAS Alert n. 4047: Not a GRB
  36. GRB070107: Swift/XRT refined analysis
  37. GRB 070107: Possible UVOT Afterglow
  38. GRB 070107, Swift-BAT refined analysis
  39. GRB 070107: Swift/XRT position
  40. GRB 070107: Swift detection of a burst
  41. VLA observation of GRB 061222B
  42. VLA detection of GRB 061222A
  43. GRB070103: APO SPIcam i' and z' limits
  44. GRB 061201: Nearby Galaxy Cluster Abell 995 is at z=0.0865
  45. GRB070103: KPNO 4m+FLAMINGOS J limit
  46. GRB 070103: Swift/UVOT Upper limits
  47. GRB070103: Swift XRT refined analysis
  48. GRB 070103, Swift-BAT refined analysis
  49. GRB 070103: NOT observations
  50. GRB 070103: TAROT Calern observatory optical observations
  51. GRB 070103: Swift detection of a burst
  52. Retractions of previous Swift-BAT triggers
  53. GRB061222a: optical observations
  54. erratum : SDSS Pre-burst Observations of GRB061126
  55. Konus-Wind observation of GRB 061222A
  56. GRB 061210: Swift/XRT Astrometry Correction
  57. GRB 050826: MDM Redshift
  58. GRB 061222B: TAROT La Silla observatory early optical observations
  59. GRB 061218: TAROT La Silla observatory early optical observations
  60. GRB 061222A: MITSuME Akeno optical upper limits
  61. GRB 061222A: Confirmation of Gemini Afterglow Candidate
  62. GRB 061222B: MITSuME Akeno optical upper limits
  63. GRB 061222A: Xinglong Optical Limit
  64. GRB 061222A: Gemini Afterglow Candidate
  65. GRB 061222B, Swift-BAT refined analysis
  66. GRB061222A Swift/UVOT: Upper Limits
  67. GRB 061222B: Swift/UVOT Upper limits
  68. GRB 061222B: Observation with the KANATA 1.5m telescope
  69. GRB061222B: Swift-XRT Refined Analysis
  70. GRB 061222A: Observation with the KANATA 1.5m telescope
  71. GRB 061222B: BOOTES-IR optical observations
  72. GRB 061222B: SARA upper limit
  73. GRB 061222A: Swift-XRT refined analysis
  74. GRB 061217: Magellan host galaxy redshift
  75. GRB 061222A, Swift-BAT refined analysis
  76. GRB 061222B: REM NIR/optical observations
  77. GRB 061222b: Refined redshift
  78. GRB 061222b, SMARTS optical/IR afterglow observations
  79. GRB 061222B: TAROT La Silla observatory afterglow observation
  80. GRB 061222B: TAROT La Silla observatory optical observations
  81. GRB 061222b: Magellan redshift
  82. GRB 061222B: Swift detection of a burst
  83. GRB 061222b: optical afterglow
  84. GRB 061222A: Prompt ROTSE-III Optical Limits
  85. GRB 061222: Swift detection of a burst
  86. GRB 061217: Astrometry-Corrected XRT Position
  87. GRB 061201: Magellan redshift of nearby galaxy
  88. GRB 061217: Confirmation of host candidate
  89. GRB 061217: Object ib GCN 5948 is a star
  90. GRB 061217: Extended object in the revised XRT error circle
  91. GRB 061217, Candidate host galaxy
  92. GRB 061217 - Swift/XRT position correction
  93. GRB 061210: Possible Host Galaxy (S2-G2) Keck Spectrum
  94. GRB 061201: Correction to GCN 5944
  95. GRB 061201: Magellan Redshift of nearby Abell cluster
  96. GRB 061218: TAROT La Silla observatory optical observations
  97. GRB 061217: TAROT Calern observatory optical observations
  98. GRB 061218: TORTOREM optical upper limits
  99. GRB 061218, Swift-BAT refined analysis
  100. GRB061217: VLT NIR observations

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