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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"

28081 results found.

  1. GRB 261005B: Swift-XRT refined Analysis
  2. EP trigger 01709320985: Ondrejov D50 optical upper limits
  3. GRB 261005A: Glowbug gamma-ray detection
  4. GRB 261005B: Swift/UVOT Upper Limits
  5. GRB 261005B: J-band upper limit with WINTER
  6. GRB 261001A: GECAM-B observation of a likely long GRB
  7. GRB 261005B: Fermi GBM Observation
  8. GRB 261005B: Enhanced Swift-XRT position
  9. GRB 261005B: Swift detection of a burst
  10. GRB 261003A: Glowbug gamma-ray detection of a likely short burst
  11. EP#01709320865: Swift-XRT observations
  12. GRB 260930B: SVOM/GRM observation
  13. Konus-Wind detection of GRB 260919A / EP 260920a
  14. EP261003a: J-band upper limit with WINTER
  15. EP261003a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  16. GRB 260930B: GECAM-B detection of a burst
  17. EP261003a: COLIBRÍ optical upper limits
  18. Fermi GRB 261003A: Global MASTER-Net observations report
  19. EP261003a: Einstein Probe detection of an X-ray transient
  20. EP Alert 261003.01: Global MASTER-Net observations report
  21. Fermi-LAT Gamma-ray Observations of IceCube-260930A
  22. Fermi GBM Detection of GRB 260919A / EP260920a
  23. IceCube-260930A: Upper limits from a search for additional neutrino events in IceCube
  24. Fermi GRB 260930B: Global MASTER-Net observations report
  25. GRB 260926C: SVOM/GRM observation
  26. IceCube Alert 260930A: Global MASTER-Net observations report
  27. EP260927a: SVOM/ECLAIRs Upper Limit
  28. EP260927a: Global MASTER-Net observations report
  29. GRB 260926B: Glowbug gamma-ray detection of a likely short burst
  30. GRB 260926A: Glowbug gamma-ray detection
  31. GRB 260924A: AbAO optical observations
  32. Fermi GRB 260928A: Global MASTER-Net observations report
  33. EP260924a: Global MASTER-Net observations report
  34. GRB 260925A: Swift-BAT refined analysis
  35. GRB 260924A: Upper limits from a neutrino search with IceCube
  36. Fermi GRB 260926C: Global MASTER-Net observations report
  37. GRB260914A: MAO/AZT-22 optical observations
  38. Fermi GRB 260926A: Global MASTER-Net observations report
  39. GRB 260924A: Near-infrared detection with MDM/MIRAGE
  40. GRB 260924A: COLIBRÍ optical observations
  41. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  42. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  43. GRB 260925A: Swift-XRT refined Analysis
  44. Swift Trigger 1513439 is probably not a GRB
  45. GRB 260925A: Swift/UVOT Upper Limits
  46. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  47. GRB 260923A: Glowbug gamma-ray detection
  48. GRB 260924A: Optical follow-up observations with Kinder
  49. GRB 260922A: Glowbug gamma-ray detection
  50. GRB 260925A: Enhanced Swift-XRT position
  51. GRB 260925A: COLIBRÍ optical upper limits
  52. GRB 260925A: FRAM-Auger optical limit
  53. GRB 260924A: Ondrejov D50 optical afterglow detection
  54. EP260924a: J-band upper limit with WINTER
  55. GRB 260924A: SVOM/GRM observation
  56. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  57. GRB 260925A: Swift detection of a burst
  58. GRB 260923A: Insight-HXMT/HE detection
  59. EP260924a: EP-WXT detection of an X-ray transient
  60. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  61. GRB 260924A: Swift/UVOT Detection
  62. GRB 260924A: GROWTH-India Telescope optical observations
  63. GRB 260924A: Swift-BAT refined analysis
  64. GRB 260924A: NuSTAR detection of prompt emission
  65. GRB 260924A: Swift-XRT refined Analysis
  66. GRB 260922A: NuSTAR detection of prompt emission
  67. GRB 260921A: NuSTAR detection of prompt emission
  68. GRB 260921A: SVOM/GRM observation
  69. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  70. GRB 260924A: Fermi GRB Observation
  71. GRB 260924A: AstroSat CZTI detection
  72. GRB 260920A: SVOM/GRM observation
  73. GRB 260924A: NOT optical counterpart confirmation
  74. GRB 260924A: Enhanced Swift-XRT position
  75. GRB 260924A: Swift detection of a burst
  76. Fermi GRB 260923A: Global MASTER-Net observations report
  77. EP260806a: e-MERLIN detection at 5 GHz
  78. GRB 260922A: Ondrejov D50 optical limit
  79. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  80. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  81. GRB 260922A: Swift-BAT refined analysis
  82. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  83. GRB 260922A: J-band upper limit with WINTER
  84. GRB 260922A: Swift/UVOT Upper Limits
  85. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  86. GRB 260922A: COLIBRÍ optical upper limits
  87. GRB 260922A: Swift-XRT refined Analysis
  88. GRB 260922A: Enhanced Swift-XRT position
  89. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  90. GRB 260920A: Glowbug gamma-ray detection
  91. GRB 260922A: SVOM/C-GFT optical upper limit
  92. GRB 260922A: Swift detection of a burst
  93. GRB 260921A: AstroSat CZTI detection
  94. GRB 260921A: Swift-BAT refined analysis
  95. GRB 260921A: Fermi GBM Observation
  96. EP Alert 260921.58: Global MASTER-Net observations report
  97. GRB 260917B:: SVOM/ECLAIRs refined analysis
  98. The EP-WXT trigger 01709319528 is likely a flaring star
  99. EP260920a: VLT/HAWK-I near-infrared candidate
  100. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)

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