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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"

28047 results found.

  1. Fermi GRB 260926A: Global MASTER-Net observations report
  2. GRB 260924A: Near-infrared detection with MDM/MIRAGE
  3. GRB 260924A: COLIBRÍ optical observations
  4. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  5. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  6. GRB 260925A: Swift-XRT refined Analysis
  7. Swift Trigger 1513439 is probably not a GRB
  8. GRB 260925A: Swift/UVOT Upper Limits
  9. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  10. GRB 260923A: Glowbug gamma-ray detection
  11. GRB 260924A: Optical follow-up observations with Kinder
  12. GRB 260922A: Glowbug gamma-ray detection
  13. GRB 260925A: Enhanced Swift-XRT position
  14. GRB 260925A: COLIBRÍ optical upper limits
  15. GRB 260925A: FRAM-Auger optical limit
  16. GRB 260924A: Ondrejov D50 optical afterglow detection
  17. EP260924a: J-band upper limit with WINTER
  18. GRB 260924A: SVOM/GRM observation
  19. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  20. GRB 260925A: Swift detection of a burst
  21. GRB 260923A: Insight-HXMT/HE detection
  22. EP260924a: EP-WXT detection of an X-ray transient
  23. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  24. GRB 260924A: Swift/UVOT Detection
  25. GRB 260924A: GROWTH-India Telescope optical observations
  26. GRB 260924A: Swift-BAT refined analysis
  27. GRB 260924A: NuSTAR detection of prompt emission
  28. GRB 260924A: Swift-XRT refined Analysis
  29. GRB 260922A: NuSTAR detection of prompt emission
  30. GRB 260921A: NuSTAR detection of prompt emission
  31. GRB 260921A: SVOM/GRM observation
  32. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  33. GRB 260924A: Fermi GRB Observation
  34. GRB 260924A: AstroSat CZTI detection
  35. GRB 260920A: SVOM/GRM observation
  36. GRB 260924A: NOT optical counterpart confirmation
  37. GRB 260924A: Enhanced Swift-XRT position
  38. GRB 260924A: Swift detection of a burst
  39. Fermi GRB 260923A: Global MASTER-Net observations report
  40. EP260806a: e-MERLIN detection at 5 GHz
  41. GRB 260922A: Ondrejov D50 optical limit
  42. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  43. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  44. GRB 260922A: Swift-BAT refined analysis
  45. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  46. GRB 260922A: J-band upper limit with WINTER
  47. GRB 260922A: Swift/UVOT Upper Limits
  48. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  49. GRB 260922A: COLIBRÍ optical upper limits
  50. GRB 260922A: Swift-XRT refined Analysis
  51. GRB 260922A: Enhanced Swift-XRT position
  52. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  53. GRB 260920A: Glowbug gamma-ray detection
  54. GRB 260922A: SVOM/C-GFT optical upper limit
  55. GRB 260922A: Swift detection of a burst
  56. GRB 260921A: AstroSat CZTI detection
  57. GRB 260921A: Swift-BAT refined analysis
  58. GRB 260921A: Fermi GBM Observation
  59. EP Alert 260921.58: Global MASTER-Net observations report
  60. GRB 260917B:: SVOM/ECLAIRs refined analysis
  61. The EP-WXT trigger 01709319528 is likely a flaring star
  62. EP260920a: VLT/HAWK-I near-infrared candidate
  63. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  64. Swift GRB 260921A: Global MASTER-Net observations report
  65. GRB 260921A: Swift detection of a burst
  66. EP260920b: LCO observations
  67. EP260920b: SVOM/VT optical observation
  68. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  69. EP260920b: COLIBRÍ optical observations
  70. EP260920b: LCO optical counterpart detection
  71. EP Alert 260921.01: Global MASTER-Net observations report
  72. EP260920b: Global MASTER-Net observations report
  73. EP260920b: Einstein Probe detection of an X-ray transient
  74. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  75. EP Alert 260920.66: Global MASTER-Net observations report
  76. EP-WXT detected a brightening of HMXB LS V +44 17
  77. EP260920a: NOT early time optical upper limits
  78. EP260920a: NOT optical upper limits
  79. EP260920a: SVOM/VT optical upper limits
  80. EP260917a: Global MASTER-Net observations report
  81. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  82. EP260920a: COLIBRÍ optical upper limits
  83. EP260917b: EP-FXT non-detection and upper limit
  84. IceCube Alert 260919A: Global MASTER-Net observations report
  85. EP260920a: LCO optical counterpart candidate
  86. EP260920a: Einstein Probe detection of an X-ray transient
  87. EP Alert 260919.40: Global MASTER-Net observations report
  88. GRB 260915A: VLT optical and near-infrared upper limits
  89. EP260917a: SVOM/VT optical upper limits
  90. GRB 260918A: SVOM/C-GFT optical upper limits
  91. EP Alert 260918.62: Global MASTER-Net observations report
  92. Fermi GBM Sub-Threshold Detection of GRB 260918A
  93. EP Alert 260918.24: Global MASTER-Net observations report
  94. SVOM GRB260918.16: Global MASTER-Net observations report
  95. GRB 260916B: Glowbug gamma-ray detection of a short burst
  96. GRB 260918A: EP-FXT follow-up observation
  97. GRB 260917B: Mondy optical upper limit
  98. EP260917b: EP-WXT detection of an X-ray transient
  99. EP260917A: J-band upper limit with WINTER
  100. EP Alert 260917.32: Global MASTER-Net observations report

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