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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"

27404 results found.

  1. GRB 260926B: Fermi GBM Final Real-time Localization
  2. Fermi GRB 260926A: Global MASTER-Net observations report
  3. GRB 260924A: Near-infrared detection with MDM/MIRAGE
  4. GRB 260926A: Fermi GBM Final Real-time Localization
  5. The EP-WXT trigger 01709320726 is likely a flaring star
  6. GRB 260924A: COLIBRÍ optical observations
  7. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  8. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  9. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  10. GRB 260925A: Swift-XRT refined Analysis
  11. Swift Trigger 1513439 is probably not a GRB
  12. GRB 260925A: Swift/UVOT Upper Limits
  13. GRB 260922A: Glowbug gamma-ray detection
  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 260924A: J-band observations by the SYSU 80 cm infrared telescope
  22. GRB 260924A: Swift/UVOT Detection
  23. GRB 260924A: GROWTH-India Telescope optical observations
  24. GRB 260924A: Swift-BAT refined analysis
  25. GRB 260924A: NuSTAR detection of prompt emission
  26. GRB 260924A: Swift-XRT refined Analysis
  27. GRB 260922A: NuSTAR detection of prompt emission
  28. GRB 260921A: NuSTAR detection of prompt emission
  29. GRB 260921A: SVOM/GRM observation
  30. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  31. GRB 260924A: Fermi GRB Observation
  32. Konus-Wind detection of GRB 260921A (possible merger-origin)
  33. GRB 260924A: Fermi-LAT detection of a bright burst
  34. GRB 260924A: AstroSat CZTI detection
  35. GRB 260920A: SVOM/GRM observation
  36. GRB 260924A: NOT optical counterpart confirmation
  37. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  38. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  39. The EP-WXT trigger 01709319842 is likely a flaring star
  40. GRB 260924A: Swift detection of a burst
  41. GRB 260924A: Fermi GBM Final Real-time Localization
  42. Fermi GRB 260923A: Global MASTER-Net observations report
  43. GRB 260923A: Fermi GBM Final Real-time Localization
  44. GRB 260922A: Ondrejov D50 optical limit
  45. GRB 260922A: Swift-BAT refined analysis
  46. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  47. GRB 260922A: J-band upper limit with WINTER
  48. GRB 260922A: Swift/UVOT Upper Limits
  49. GRB 260922A: COLIBRÍ optical upper limits
  50. GRB 260922A: Swift-XRT refined Analysis
  51. GRB 260918A: SVOM/ECLAIRs refined analysis
  52. GRB 260922A: SVOM/C-GFT optical upper limit
  53. GRB 260922A: Swift detection of a burst
  54. GRB 260921A: AstroSat CZTI detection
  55. GRB 260921A: Swift-BAT refined analysis
  56. GRB 260921B: Fermi GBM Final Localization
  57. GRB 260921A: Fermi GBM Observation
  58. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  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: Global MASTER-Net observations report
  64. GRB 260921A: Swift detection of a burst
  65. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  66. GRB 260921A: Fermi GBM Final Real-time Localization
  67. EP260920b: LCO observations
  68. EP260920b: SVOM/VT optical observation
  69. EP260920b: COLIBRÍ optical observations
  70. EP260920b: LCO optical counterpart detection
  71. The EP-WXT trigger 01709318601 is likely a flaring star
  72. EP Alert 260921.01: Global MASTER-Net observations report
  73. EP260920b: Global MASTER-Net observations report
  74. EP Alert 260920.66: Global MASTER-Net observations report
  75. EP260920a: NOT early time optical upper limits
  76. EP260920a: NOT optical upper limits
  77. GRB 260920A: Fermi GBM Final Real-time Localization
  78. EP260920a: SVOM/VT optical upper limits
  79. EP260917a: Global MASTER-Net observations report
  80. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  81. EP260920a: COLIBRÍ optical upper limits
  82. IceCube Alert 260919A: Global MASTER-Net observations report
  83. EP260920a: LCO optical counterpart candidate
  84. EP Alert 260919.40: Global MASTER-Net observations report
  85. The EP-WXT trigger 01709318491 is likely a flaring star
  86. EP260917a: SVOM/VT optical upper limits
  87. GRB 260918A: SVOM/C-GFT optical upper limits
  88. EP Alert 260918.62: Global MASTER-Net observations report
  89. Fermi GBM Sub-Threshold Detection of GRB 260918A
  90. EP Alert 260918.24: Global MASTER-Net observations report
  91. SVOM GRB260918.16: Global MASTER-Net observations report
  92. The EP-WXT trigger 01709318279 is likely a flaring star
  93. GRB 260918A: EP-FXT follow-up observation
  94. GRB 260917B: Mondy optical upper limit
  95. IPN triangulation of GRB 260916B (short)
  96. EP Alert 260917.32: Global MASTER-Net observations report
  97. GRB 260917B: EP-FXT follow-up observation
  98. EP260917a: COLIBRÍ optical upper limits
  99. GRB 260918A: LCO optical upper limits
  100. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits

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