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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"

28040 results found.

  1. GRB 260925A: Swift-XRT refined Analysis
  2. Swift Trigger 1513439 is probably not a GRB
  3. GRB 260925A: Swift/UVOT Upper Limits
  4. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  5. GRB 260923A: Glowbug gamma-ray detection
  6. GRB 260924A: Optical follow-up observations with Kinder
  7. GRB 260922A: Glowbug gamma-ray detection
  8. GRB 260925A: Enhanced Swift-XRT position
  9. GRB 260925A: COLIBRÍ optical upper limits
  10. GRB 260925A: FRAM-Auger optical limit
  11. GRB 260924A: Ondrejov D50 optical afterglow detection
  12. EP260924a: J-band upper limit with WINTER
  13. GRB 260924A: SVOM/GRM observation
  14. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  15. GRB 260925A: Swift detection of a burst
  16. GRB 260923A: Insight-HXMT/HE detection
  17. EP260924a: EP-WXT detection of an X-ray transient
  18. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  19. GRB 260924A: Swift/UVOT Detection
  20. GRB 260924A: GROWTH-India Telescope optical observations
  21. GRB 260924A: Swift-BAT refined analysis
  22. GRB 260924A: NuSTAR detection of prompt emission
  23. GRB 260924A: Swift-XRT refined Analysis
  24. GRB 260922A: NuSTAR detection of prompt emission
  25. GRB 260921A: NuSTAR detection of prompt emission
  26. GRB 260921A: SVOM/GRM observation
  27. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  28. GRB 260924A: Fermi GRB Observation
  29. GRB 260924A: AstroSat CZTI detection
  30. GRB 260920A: SVOM/GRM observation
  31. GRB 260924A: NOT optical counterpart confirmation
  32. GRB 260924A: Enhanced Swift-XRT position
  33. GRB 260924A: Swift detection of a burst
  34. Fermi GRB 260923A: Global MASTER-Net observations report
  35. EP260806a: e-MERLIN detection at 5 GHz
  36. GRB 260922A: Ondrejov D50 optical limit
  37. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  38. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  39. GRB 260922A: Swift-BAT refined analysis
  40. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  41. GRB 260922A: J-band upper limit with WINTER
  42. GRB 260922A: Swift/UVOT Upper Limits
  43. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  44. GRB 260922A: COLIBRÍ optical upper limits
  45. GRB 260922A: Swift-XRT refined Analysis
  46. GRB 260922A: Enhanced Swift-XRT position
  47. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  48. GRB 260920A: Glowbug gamma-ray detection
  49. GRB 260922A: SVOM/C-GFT optical upper limit
  50. GRB 260922A: Swift detection of a burst
  51. GRB 260921A: AstroSat CZTI detection
  52. GRB 260921A: Swift-BAT refined analysis
  53. GRB 260921A: Fermi GBM Observation
  54. EP Alert 260921.58: Global MASTER-Net observations report
  55. GRB 260917B:: SVOM/ECLAIRs refined analysis
  56. The EP-WXT trigger 01709319528 is likely a flaring star
  57. EP260920a: VLT/HAWK-I near-infrared candidate
  58. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  59. Swift GRB 260921A: Global MASTER-Net observations report
  60. GRB 260921A: Swift detection of a burst
  61. EP260920b: LCO observations
  62. EP260920b: SVOM/VT optical observation
  63. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  64. EP260920b: COLIBRÍ optical observations
  65. EP260920b: LCO optical counterpart detection
  66. EP Alert 260921.01: Global MASTER-Net observations report
  67. EP260920b: Global MASTER-Net observations report
  68. EP260920b: Einstein Probe detection of an X-ray transient
  69. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  70. EP Alert 260920.66: Global MASTER-Net observations report
  71. EP-WXT detected a brightening of HMXB LS V +44 17
  72. EP260920a: NOT early time optical upper limits
  73. EP260920a: NOT optical upper limits
  74. EP260920a: SVOM/VT optical upper limits
  75. EP260917a: Global MASTER-Net observations report
  76. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  77. EP260920a: COLIBRÍ optical upper limits
  78. EP260917b: EP-FXT non-detection and upper limit
  79. IceCube Alert 260919A: Global MASTER-Net observations report
  80. EP260920a: LCO optical counterpart candidate
  81. EP260920a: Einstein Probe detection of an X-ray transient
  82. EP Alert 260919.40: Global MASTER-Net observations report
  83. GRB 260915A: VLT optical and near-infrared upper limits
  84. EP260917a: SVOM/VT optical upper limits
  85. GRB 260918A: SVOM/C-GFT optical upper limits
  86. EP Alert 260918.62: Global MASTER-Net observations report
  87. Fermi GBM Sub-Threshold Detection of GRB 260918A
  88. EP Alert 260918.24: Global MASTER-Net observations report
  89. SVOM GRB260918.16: Global MASTER-Net observations report
  90. GRB 260916B: Glowbug gamma-ray detection of a short burst
  91. GRB 260918A: EP-FXT follow-up observation
  92. GRB 260917B: Mondy optical upper limit
  93. EP260917b: EP-WXT detection of an X-ray transient
  94. EP260917A: J-band upper limit with WINTER
  95. EP Alert 260917.32: Global MASTER-Net observations report
  96. GRB 260917B: EP-FXT follow-up observation
  97. EP260917a: COLIBRÍ optical upper limits
  98. GRB 260915A: Swift-XRT afterglow detection
  99. GRB 260918A: LCO optical upper limits
  100. EP260917a: Einstein Probe detection of an X-ray transient

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