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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"

26489 results found.

  1. GRB 260925A: Swift/UVOT Upper Limits
  2. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  3. GRB 260923A: Glowbug gamma-ray detection
  4. GRB 260924A: Optical follow-up observations with Kinder
  5. GRB 260922A: Glowbug gamma-ray detection
  6. GRB 260925A: Enhanced Swift-XRT position
  7. GRB 260925A: COLIBRÍ optical upper limits
  8. GRB 260925A: FRAM-Auger optical limit
  9. GRB 260924A: Ondrejov D50 optical afterglow detection
  10. EP260924a: J-band upper limit with WINTER
  11. GRB 260924A: SVOM/GRM observation
  12. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  13. GRB 260925A: Swift detection of a burst
  14. EP260924a: EP-WXT detection of an X-ray transient
  15. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  16. GRB 260924A: Swift/UVOT Detection
  17. GRB 260924A: GROWTH-India Telescope optical observations
  18. GRB 260924A: Swift-XRT refined Analysis
  19. Konus-Wind detection of GRB 260922A
  20. GRB 260921A: SVOM/GRM observation
  21. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  22. GRB 260924A: Fermi GRB Observation
  23. Konus-Wind detection of GRB 260921A (possible merger-origin)
  24. GRB 260924A: AstroSat CZTI detection
  25. GRB 260920A: SVOM/GRM observation
  26. GRB 260924A: NOT optical counterpart confirmation
  27. GRB 260924A: Enhanced Swift-XRT position
  28. The EP-WXT trigger 01709319842 is likely a flaring star
  29. GRB 260924A: Swift detection of a burst
  30. EP260806a: e-MERLIN detection at 5 GHz
  31. GRB 260922A: Ondrejov D50 optical limit
  32. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  33. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  34. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  35. GRB 260922A: J-band upper limit with WINTER
  36. GRB 260922A: Swift/UVOT Upper Limits
  37. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  38. GRB 260922A: COLIBRÍ optical upper limits
  39. GRB 260922A: Swift-XRT refined Analysis
  40. GRB 260922A: Enhanced Swift-XRT position
  41. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  42. Konus-Wind detection of GRB 260810A
  43. GRB 260920A: Glowbug gamma-ray detection
  44. GRB 260918A: SVOM/ECLAIRs refined analysis
  45. GRB 260922A: SVOM/C-GFT optical upper limit
  46. GRB 260922A: Swift detection of a burst
  47. GRB 260917C: AstroSat CZTI detection
  48. GRB 260921A: AstroSat CZTI detection
  49. GRB 260921A: Fermi GBM Observation
  50. GRB 260917B:: SVOM/ECLAIRs refined analysis
  51. The EP-WXT trigger 01709319528 is likely a flaring star
  52. EP260920a: VLT/HAWK-I near-infrared candidate
  53. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  54. EP260920b: LCO observations
  55. GRB 260920A: AstroSat CZTI detection
  56. EP260920b: SVOM/VT optical observation
  57. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  58. EP260920b: COLIBRÍ optical observations
  59. EP260920b: LCO optical counterpart detection
  60. The EP-WXT trigger 01709318601 is likely a flaring star
  61. EP260920b: Einstein Probe detection of an X-ray transient
  62. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  63. EP-WXT detected a brightening of HMXB LS V +44 17
  64. EP260920a: NOT early time optical upper limits
  65. EP260920a: NOT optical upper limits
  66. EP260920a: SVOM/VT optical upper limits
  67. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  68. EP260920a: COLIBRÍ optical upper limits
  69. EP260917b: EP-FXT non-detection and upper limit
  70. EP260920a: LCO optical counterpart candidate
  71. EP260920a: Einstein Probe detection of an X-ray transient
  72. GRB 260915A: VLT optical and near-infrared upper limits
  73. EP260917a: refined analysis of the EP-FXT observations
  74. The EP-WXT trigger 01709318491 is likely a flaring star
  75. EP260917a: SVOM/VT optical upper limits
  76. GRB 260918A: SVOM/C-GFT optical upper limits
  77. Konus-Wind detection of GRB 260916B (short/hard)
  78. The EP-WXT trigger 01709318279 is likely a flaring star
  79. GRB 260916B: Glowbug gamma-ray detection of a short burst
  80. GRB 260918A: EP-FXT follow-up observation
  81. GRB 260917B: Mondy optical upper limit
  82. EP260917b: EP-WXT detection of an X-ray transient
  83. EP260917A: J-band upper limit with WINTER
  84. GRB 260917B: EP-FXT follow-up observation
  85. EP260917a: COLIBRÍ optical upper limits
  86. GRB 260915A: Swift-XRT afterglow detection
  87. GRB 260918A: LCO optical upper limits
  88. EP260917a: Einstein Probe detection of an X-ray transient
  89. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  90. GRB 260918A: SVOM detection of a burst
  91. GRB 260917B: FRAM-Auger optical limits
  92. GRB 260916B: Fermi GBM Detection
  93. IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
  94. GRB 260917A: Glowbug gamma-ray detection
  95. GRB 260915A: SVOM/ECLAIRs refined analysis
  96. GRB 260917B: WINTER J-band observations
  97. GRB 260917B: SVOM/VT optical observations
  98. GRB 260917B: LCO optical observation
  99. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  100. GRB 260917B: SVOM detection of a faint burst

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