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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"

27400 results found.

  1. The EP-WXT trigger 01709320726 is likely a flaring star
  2. GRB 260924A: COLIBRÍ optical observations
  3. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  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 260922A: Glowbug gamma-ray detection
  10. GRB 260925A: COLIBRÍ optical upper limits
  11. GRB 260925A: FRAM-Auger optical limit
  12. GRB 260924A: Ondrejov D50 optical afterglow detection
  13. EP260924a: J-band upper limit with WINTER
  14. GRB 260924A: SVOM/GRM observation
  15. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  16. GRB 260925A: Swift detection of a burst
  17. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  18. GRB 260924A: Swift/UVOT Detection
  19. GRB 260924A: GROWTH-India Telescope optical observations
  20. GRB 260924A: Swift-BAT refined analysis
  21. GRB 260924A: NuSTAR detection of prompt emission
  22. GRB 260924A: Swift-XRT refined Analysis
  23. GRB 260922A: NuSTAR detection of prompt emission
  24. GRB 260921A: NuSTAR detection of prompt emission
  25. GRB 260921A: SVOM/GRM observation
  26. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  27. GRB 260924A: Fermi GRB Observation
  28. Konus-Wind detection of GRB 260921A (possible merger-origin)
  29. GRB 260924A: Fermi-LAT detection of a bright burst
  30. GRB 260924A: AstroSat CZTI detection
  31. GRB 260920A: SVOM/GRM observation
  32. GRB 260924A: NOT optical counterpart confirmation
  33. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  34. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  35. The EP-WXT trigger 01709319842 is likely a flaring star
  36. GRB 260924A: Swift detection of a burst
  37. GRB 260924A: Fermi GBM Final Real-time Localization
  38. Fermi GRB 260923A: Global MASTER-Net observations report
  39. GRB 260923A: Fermi GBM Final Real-time Localization
  40. GRB 260922A: Ondrejov D50 optical limit
  41. GRB 260922A: Swift-BAT refined analysis
  42. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  43. GRB 260922A: J-band upper limit with WINTER
  44. GRB 260922A: Swift/UVOT Upper Limits
  45. GRB 260922A: COLIBRÍ optical upper limits
  46. GRB 260922A: Swift-XRT refined Analysis
  47. GRB 260918A: SVOM/ECLAIRs refined analysis
  48. GRB 260922A: SVOM/C-GFT optical upper limit
  49. GRB 260922A: Swift detection of a burst
  50. GRB 260921A: AstroSat CZTI detection
  51. GRB 260921A: Swift-BAT refined analysis
  52. GRB 260921B: Fermi GBM Final Localization
  53. GRB 260921A: Fermi GBM Observation
  54. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  55. EP Alert 260921.58: Global MASTER-Net observations report
  56. GRB 260917B:: SVOM/ECLAIRs refined analysis
  57. The EP-WXT trigger 01709319528 is likely a flaring star
  58. EP260920a: VLT/HAWK-I near-infrared candidate
  59. Swift GRB 260921A: Global MASTER-Net observations report
  60. GRB 260921A: Swift detection of a burst
  61. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  62. GRB 260921A: Fermi GBM Final Real-time Localization
  63. EP260920b: LCO observations
  64. EP260920b: SVOM/VT optical observation
  65. EP260920b: COLIBRÍ optical observations
  66. EP260920b: LCO optical counterpart detection
  67. The EP-WXT trigger 01709318601 is likely a flaring star
  68. EP Alert 260921.01: Global MASTER-Net observations report
  69. EP260920b: Global MASTER-Net observations report
  70. EP Alert 260920.66: Global MASTER-Net observations report
  71. EP260920a: NOT early time optical upper limits
  72. EP260920a: NOT optical upper limits
  73. GRB 260920A: Fermi GBM Final Real-time Localization
  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. IceCube Alert 260919A: Global MASTER-Net observations report
  79. EP260920a: LCO optical counterpart candidate
  80. EP Alert 260919.40: Global MASTER-Net observations report
  81. The EP-WXT trigger 01709318491 is likely a flaring star
  82. EP260917a: SVOM/VT optical upper limits
  83. GRB 260918A: SVOM/C-GFT optical upper limits
  84. EP Alert 260918.62: Global MASTER-Net observations report
  85. Fermi GBM Sub-Threshold Detection of GRB 260918A
  86. EP Alert 260918.24: Global MASTER-Net observations report
  87. SVOM GRB260918.16: Global MASTER-Net observations report
  88. The EP-WXT trigger 01709318279 is likely a flaring star
  89. GRB 260918A: EP-FXT follow-up observation
  90. GRB 260917B: Mondy optical upper limit
  91. IPN triangulation of GRB 260916B (short)
  92. EP Alert 260917.32: Global MASTER-Net observations report
  93. GRB 260917B: EP-FXT follow-up observation
  94. EP260917a: COLIBRÍ optical upper limits
  95. GRB 260918A: LCO optical upper limits
  96. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  97. GRB 260918A: SVOM detection of a burst
  98. GRB 260917C: Fermi GBM Final Real-time Localization
  99. GRB 260917B: FRAM-Auger optical limits
  100. GRB 260916B: Fermi GBM Detection

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